Chapter 1. Welcome to EJB
Table of Contents Chapter 1. Welcome to EJB.......................................................................... 1 Section 1.1. OBJECTIVES............................................................................................................................................................... 2 Section 1.2. What is EJB all about?................................................................................................................................................. 3 Section 1.3. What does EJB really give me?................................................................................................................................... 4 Section 1.4. No more vendor lock-in!............................................................................................................................................. 5 Section 1.5. There are no Dumb Questions.................................................................................................................................... 6 Section 1.6. How does it all work?................................................................................................................................................... 7 Section 1.7. Behind the scenes........................................................................................................................................................ 8 Section 1.8. Sharpen your pencil................................................................................................................................................... 10 Section 1.9. Beans come in three flavors....................................................................................................................................... 11 Section 1.10. Session beans can be stateless or stateful................................................................................................................ 12 Section 1.11. There are no Dumb Question................................................................................................................................... 12 Section 1.12. Sharpen your pencil.................................................................................................................................................. 13 Section 1.13. Overheard at! THE TIKIBEAN LOUNGE................................................................................................................ 14 Section 1.14. Example: The Advice Guy bean................................................................................................................................ 15 Section 1.15. Five things you do to build a bean:.......................................................................................................................... 16 Section 1.16. EJB Roles and Responsibilities............................................................................................................................... 26 Section 1.17. Tutorial:.................................................................................................................................................................... 28 Section 1.18. Organize your project directory............................................................................................................................... 29 Section 1.19. Compile the two interfaces and the bean class....................................................................................................... 30 Section 1.20. Start the server......................................................................................................................................................... 31 Section 1.21. You'll see something like this................................................................................................................................... 31 Section 1.22. Start deploytool....................................................................................................................................................... 32 Section 1.23. you'll see something like this................................................................................................................................... 32 Section 1.24. Make a new Application.......................................................................................................................................... 33 Section 1.25. There are no Dumb Questions................................................................................................................................ 33 Section 1.26. Name and save the new application........................................................................................................................ 34 Section 1.27. What you'll see af ter you create and name the application................................................................................... 35 Section 1.28. Now let's make the new enterprise bean (the ejb-jar and the DD)........................................................................ 36 Section 1.29. Now we're in the really cool New Enterprise Bean Wizard.................................................................................... 37 Section 1.30. Create the new ejb-jar............................................................................................................................................. 38 Section 1.31. Add the three class files (including their package directory) to the JAR............................................................... 39 Section 1.32. Confirm that you added ONLY the package directory and the class files.............................................................. 40 Section 1.33. Make it a Stateless Session bean.............................................................................................................................. 41 Section 1.34. Tell it which of the three class files in the JAR is the actual BEAN class............................................................... 42 Section 1.35. Tell it which is the Home interface, and which is the Component interface......................................................... 43 Section 1.36. Verify everything on this screen!............................................................................................................................ 44 Section 1.37. You're done, click Finish.......................................................................................................................................... 45 Section 1.38. Meanwhile back on the main deploytool screen.................................................................................................... 46 Section 1.39. Run your bean through the deploytool verifier...................................................................................................... 47 Section 1.40. Close your eyes and click OK.................................................................................................................................. 48 Section 1.41. Whew! No failed tests.............................................................................................................................................. 49 Section 1.42. Time to Deploy........................................................................................................................................................ 50 Section 1.43. Make it Return a Client Jar...................................................................................................................................... 51 Section 1.44. Give it a name, so clients can look it up.................................................................................................................. 52 Section 1.45. Watch the progress bars go up, then celebrate....................................................................................................... 53 Section 1.46. Now you'll see the AdviceApp inside the server..................................................................................................... 54 Section 1.47. Now all we need is a client....................................................................................................................................... 55 Section 1.48. Organizing your project directory for the client..................................................................................................... 56 Section 1.49. The Client Code (AdviceClient.java)....................................................................................................................... 57 Section 1.50. Run the client!......................................................................................................................................................... 58 Section 1.51. COFFEE CRAM........................................................................................................................................................ 59 Section 1.52. COFFEE CRAM....................................................................................................................................................... 60
Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Intro to EJB
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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#AN ) USE %*" COMPONENTS WITHOUT AN %*" COMPLIANT APP SERVER
.OPE %*" COMPONENTS CANT LIVE OUTSIDE OF AN %*" CONTAINER 4HEY DONT HAVE A MAIN METHOD AND EVEN IF YOU ADD ONE TO YOUR BEAN CLASS THE BEAN WOULDNT BE VERY USEFUL ON ITS OWN -OST OF THE METHODS IN AN ENTERPRISE BEAN ARE CALLED BY THE CONTAINER ITSELF AND HAVE NO MEANING OUTSIDE THE SERVER 2EMEMBER THE WHOLE POINT OF AN %*" SERVER IS TO GIVE YOU ALL THE BIG SERVICES SECURITY TRANSACTIONS ETC AND WITHOUT THE SERVER YOUD LOSE EVERYTHING BUT YOUR BASIC BUSINESS LOGIC !ND IF THAT BUSINESS LOGIC RELIES ON THE CONTAINER FOR EXAMPLE CALLING METHODS ON INTERFACES PROVIDED BY THE CONTAINER THEN EVEN THE BUSINESS LOGIC WOULD FAIL
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#AN ) DESIGN AND WRITE MY CODE IN SUCH A WAY THAT MOST OF THE BUSINESS LOGIC IS IN A PLAIN OLD *AVA CLASS AND JUST HAVE THE BEAN CALL METHODS ON THAT CLASS 4HAT WAY ) COULD STILL REUSE THE BUSINESS LOGIC
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9ES YOU CAN DO THAT AND IN FACT A LOT OF DESIGNERS WRITE SEPARATE NON BEAN REUSABLE CLASSES AND THEN HAVE THE BEANS INVOKE METHODS ON THOSE CLASSES )F YOUR BEAN CALLS A METHOD ON A NON BEAN *AVA CLASS THAT METHOD IS STILL UNDER THE CONTROL OF THE CONTAINER SO AS FAR AS THE CONTAINER IS CONCERNED THAT NON BEAN METHOD IS JUST PART OF THE BEANS FUNCTIONALITY
7HATS THE DIFFERENCE BETWEEN REGULAR JAVABEANS AND ENTERPRISE JAVABEANS
#ONGRATULATIONS 9OURE THE MILLIONTH PERSON TO HAVE ASKED THAT QUESTION 4HE TERM hJAVABEANv MEANS A REUSABLE COMPONENT 2EGULAR OLD NON ENTERPRISE BEANS AND BEANS IS JUST A SHORTER FORM OF JAVABEANS ARE REUSABLE COMPONENTS THAT FOLLOW A NAMING CONVENTION THAT CAN BE USED BY DEVELOPMENT TOOLS "Y FAR THE MOST COMMON TYPE OF JAVABEAN IS ANY '5) COMPONENT LIKE A 3WING BUTTON OR TEXT FIELD .EARLY ALL *AVA )$%S ARE JAVABEAN COMPLIANT SO THAT IF YOURE WORKING IN A VISUAL LAYOUT TOOL YOU CAN CLICK ON A BUTTON AND UP POPS A PROPERTY SHEET WHERE YOU CAN SET THE COLOR SIZE FONT ETC 4HE TOOL KNOWS WHICH PROPERTIES THE BEAN HAS BECAUSE THE BEAN FOLLOWS CONVENTIONS FOR GETTERS AND SETTERS "UT REGULAR JAVABEANS ARENT JUST FOR '5) COMPONENTSOTHER *AVA TECHNOLOGIES INCLUDING *INI AND 3ERVLETS CAN USE JAVABEAN FEATURES %NTERPRISE JAVABEANS ARE ALSO REUSABLE COMPONENTS BUT THATS WHERE THE SIMILARITY ENDS 4HE @BEAN PART OF A REGULAR JAVABEAN IS USED MOSTLY AT DEVELOPMENT TIME AS A WAY TO EASE OR SPEED UP HOOKING ONE BEANS EVENTS TO ANOTHER BEANS METHODS OR SETTING PROPERTY VALUES WHICH OFTEN MEAN THE SAME THING AS INSTANCE VARIABLE VALUES ! REGULAR BEAN RUNS IN A *6- JUST LIKE ANY OTHER NORMAL *AVA CLASS "UT THE hBEANv PART OF AN ENTERPRISE BEAN KICKS IN AT RUNTIME AND AN ENTERPRISE BEAN MUST BE RUN UNDER THE CONTROL OF AN %*" CONTAINER &OR THE REST OF THE BOOK WHEN WE SAY BEAN WE MEAN ENTERPRISE BEAN
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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5SE AN ENTITY BEAN TO REPRESENT A THING IN A PERSISTENT STORE 4HAT ALMOST ALWAYS MEANS SOMETHING IN A DATABASE WHERE AN INSTANCE OF AN ENTITY BEAN REPRESENTS A ROW IN A TABLE ALTHOUGH IF THE DATABASE IS NORMALIZED THE BEAN MIGHT BE DRAWING FROM ROWS IN MULTIPLE TABLES ! TYPICAL ENTITY EXAMPLE IS #USTOMER WHERE ONE ENTITY MIGHT REPRESENT "O /LEAN )$ AND ANOTHER ENTITY MIGHT REPRESENT 4RIXIA ,IN )$
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[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 1. Welcome to EJB
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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"EFORE WE GET INTO THE GUTS OF %*" LETS LOOK AT HOW TO DEVELOP DEPLOY AND TEST A BEAN FROM START TO lNISH )F YOURE NOT ALREADY FAMILIAR WITH %*" YOU WONT UNDERSTAND EVERYTHING HERE $ONT WORRY ABOUT IT NOW WELL lGURE IT ALL OUT IN LATER CHAPTERS 4HIS IS JUST TO GIVE YOU A FEELING FOR WHAT ITS LIKE TO GET A BEAN UP AND RUNNING /UR lRST BEAN IS FOR THE !DVICE 'UY SERVICEA REMOTE SERVICE THAT GIVES BACK AN ADVICE 3TRING EACH TIME THE CLIENT MAKES A REQUEST 7ELL SPEND THE NEXT SEVERAL PAGES LOOKING AT THE PROCESS AND THEN WELL ACTUALLY MAKE THIS BEAN AS A TUTORIAL
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 18
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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(MMM TWO GOOD QUESTIONS )N A NON BEAN *AVA WORLD THE WAY WERE DOING THINGS HERE WOULDNT MAKE MUCH SENSE "UT BEAN WORLD HAS DIFFERENT RULES AND PRACTICES 7E COULD WRITE THE INTERFACES lRST AND SOME DEVELOPERS DO 3OMETIMES THE CHOICE OF WHICH TO DEVELOP lRST DEPENDS ON THE DEVELOPMENT TOOLS YOURE USING TO BUILD YOUR BEANS 3OME TOOLS FOR EXAMPLE EXPECT YOU TO lRST BUILD YOUR BEAN CODING THE ACTUAL BUSINESS LOGIC AND THEN THE TOOL WILL BUILD THE INTERFACES TO MATCH !ND SOME TOOLS DO JUST THE OPPOSITE LOOKING AT THE INTERFACES AND BUILDING A hYOUR CODE GOES HEREv BEAN CLASS WITH ALL OF THE METHODS FROM THE INTERFACE &OR LEARNING %*" WE LIKE TO START WITH THE BEAN FOCUSING ON THE BUSINESS LOGIC BEFORE lGURING OUT THE INTERFACES ,ATER IN THE BOOK WELL DO IT THE OTHER WAY AROUND !S FOR THE BEAN NOT IMPLEMENTING THE COMPONENT INTERFACE YOU COULD DO IT THAT WAY BUT THIS TIME WE STRONGLY URGE YOU NOT TO /N THE NEXT PAGE WELL LOOK AT THIS IN MORE DETAIL
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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3O WHY DOESNT THE BEAN CLASS !DVICE"EAN IMPLEMENT THE COMPONENT INTERFACE !DVICE IF IT HAS TO IMPLEMENT THE SAME METHODS *AVA CLASSES ARE ALLOWED TO IMPLEMENT MORE THAN ONE INTERFACE SO WHATS THE PROBLEM WITH SAYING
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"UT THERES AN EASY SOLUTION TO 4(!4 PROBLEM YOU COULD HAVE THE BEAN EXTEND A CLASS THAT HAS ALL THE IMPLEMENTATIONS THAT YOU NEED TO SATISFY THE COMPILER BUT DONT REALLY NEED TO IMPLEMENT IN YOUR CODE ,IKE THE ADAPTER EVENT LISTENER CLASSES IN !74 7HY NOT DO SOMETHING LIKE THAT HERE AND MAKE A SUPERCLASS FOR YOUR BEAN THAT IMPLEMENTS THE METHODS
A:
A:
,EGALLY THE BEAN CLASS CAN IMPLEMENT THE COMPONENT INTERFACE BUT THE SPEC DOESNT RECOMMEND IT 2EMEMBER ALTHOUGH TO THE CLIENT IT LOOKS AS THOUGH THE !DVICE"EAN IS THE OBJECT THE CLIENTS INVOKING METHODS ON THE OBJECT THAT IMPLEMENTSIN THE TRUE *AVA SENSETHE COMPONENT INTERFACE THE CLIENT REALLY INVOKES METHODS ON SOMETHING CALLED AN %*"/BJECT THATS IMPLEMENTED BY THE SERVER AT DEPLOY TIME 4HE CLIENT NEVER INTERACTS DIRECTLY WITH THE BEAN .EVER EVER EVER ,ATER IN THE BOOK YOULL SEE THAT IF THE BEAN DOES IMPLEMENT THE COMPONENT INTERFACE YOU COULD SNEAK THINGS PAST THE COMPILER THAT WOULD EXPLODE AT RUNTIME 3O WE STRONGLY URGE YOU NOT TO HAVE YOUR BEAN IMPLEMENT THE COMPONENT INTERFACE "UT THERES ANOTHER ISSUE AS WELLTHE COMPONENT INTERFACE EXTENDS ANOTHER INTERFACE )N OUR EXAMPLE !DVICE EXTENDS %*"/BJECT AND %*"/BJECT IS NOT A MARKER INTERFACE )T HAS METHODS 4HIS MEANS THAT ANY CLASS IMPLEMENTING !DVICE MUST ALSO IMPLEMENT THE METHODS OF %*"/BJECT
9ES YOU COULD DO THAT AND IT WOULD BE LEGAL "UT IT STILL MEANS YOUR BEAN IS CAPABLE OF HAVING METHODS INVOKED THAT THE BEAN SHOULD NEVER KNOW ABOUT 4HE METHODS OF %*"/BJECT ARE METHODS FOR THE CLIENT TO CALL ON THE BEAN BUT ./4 FOR THE BEAN TO ACTUALLY IMPLEMENT 3O ITS NOT THE BEST // PRACTICE !ND THERES STILL ANOTHER REASON WHY ITS NOT GOOD PRACTICE TO HAVE THE BEAN IMPLEMENT THE COMPONENT INTERFACEIF THE INTERFACE IS REMOTE AND %*"/BJECT IS SINCE IT EXTENDS THE JAVARMI2EMOTE INTERFACE THAT WOULD MAKE THE BEAN CLASS A 2EMOTE CLASS AND THAT MUST NEVER BE 4HE BEAN IS PROTECTED BY THE SERVER AND MUST NEVER BE ACCESSED IN ANY OTHER WAY BY ANYTHING BUT THE SERVER )TS THE SERVER THAT MAKES THE %*"/BJECT BY IMPLEMENTING THE !DVICE INTERFACE WHICH )3 REMOTE AND WHICH INTERCEPTS ALL BUSINESS METHOD CALLS TO THE BEAN
Q:
"UT IF YOU DONT HAVE THE BEAN IMPLEMENT THE INTERFACE IN OTHER WORDS IF !DVICE"EAN DOESNT IMPLEMENT !DVICE DOESNT THIS MEAN THAT THE COMPILER WONT CATCH YOU IF THE BEAN BLOWS IT AND DOESNT MATCH THE METHODS OF THE INTERFACE
A:
9ES THATS EXACTLY WHAT IT MEANS !ND YES THAT MAKES MOST *AVA DEVELOPERS A LITTLE QUEASY JUST THINKING ABOUT IT !FTER ALL THATS ONE OF THE BENEFITS OF INTERFACES IN *AVA THAT THE COMPILER GUARANTEES THAT YOU HAVE ALL OF THE INTERFACE METHODS PROPERLY IMPLEMENTED "UT DONT PANIC )N OUR DEVELOPMENT IN THIS BOOK WE DO HAVE TO BE CAREFUL SINCE THE COMPILER ISNT MAKING SURE THAT WEVE IMPLEMENTED THE BUSINESS METHODS FROM THE COMPONENT INTERFACE )N THE REAL WORLD HOWEVER YOULL ALMOST CERTAINLY BE USING AN %*" READY DEVELOPMENT ENVIRONMENT THAT WILL MAKE SURE YOU PROVIDE THE METHODS EITHER BY PUTTING A hYOUR CODE GOES HEREv VERSION OF THE METHOD IN YOUR BEAN CLASS OR BY DOING THE REVERSEFINDING THE BUSINESS METHOD IN THE BEAN CLASS AND PUTTING IT INTO THE COMPONENT INTERFACE !T THE VERY LEAST MOST SERVERS WILL CHECK BEFORE OR AT THE TIME YOU DEPLOY THE BEAN THAT YOUR COMPONENT INTERFACE AND BEAN CLASS HAVE MATCHING METHODS
)F THIS STILL BOTHERS YOU THOUGH WE DO HAVE A TECHNIQUE FOR GETTING AROUND IT THAT WELL LOOK AT A LITTLE LATER #HANCES ARE YOU WONT NEED TO USE IT
3O YOUR BEAN WOULD END UP IMPLEMENTING A BUNCH OF METHODS IT SHOULD NEVER HAVE LIKE GET(ANDLE GET%*"(OME
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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You donÕt have to write the XML by hand if you use a tool that can help you build a deployment descriptor. You can use the J2EE RI bean wizard to do it for you, and the XML it spits out will work in any EJB 2.0 container!
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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!S A BEAN DEVELOPER OFl CIALLY CALLED A "EAN 0ROVIDER YOULL ALWAYS PUT YOUR BEANS IN A *!2 4HE SPEC SAYS AN EJB JAR IS A *!2 l LE THAT HOLDS THE THINGS THE BEAN DEPENDS ON CLASSES AND INTERFACES ALONG WITH THE DEPLOYMENT DESCRIPTOR 9OU DONT HAVE TO DO THIS BY HAND SINCE WELL USE THE 2) 2ATHER THAN WRITING THE 8-, $$ AND USING THE MDU TOOL TO PACKAGE IT WELL USE THE 2) GHSOR\WRRO WIZARD TO MAKE IT EASIER AND LESS ERROR PRONE )N OTHER WORDS WERE GOING TO COMBINE STEPS AND INTO ONE &OR NOW YOU NEED TO KNOW THAT A BEAN ISNT A BEAN UNTIL YOU MAKE A *!2 l LE WITH THE COMPILED CLASS AND INTERFACES AND THE $$
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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3OONER OR LATER YOUR BEANS HAVE TO DO SOMETHING 4HEY HAVE TO BE ASSEMBLED INTO AN APPLICATION AND DEPLOYED INTO A SERVER WAITING FOR CLIENTS TO CALL 4HIS IS A HUGE STEP )N FACT WE CHEATED A LITTLE BECAUSE ITS ACTUALLY TWO STEPS !PPLICATION !SSEMBLY AND $EPLOYMENT 5!PPLICATION !SSEMBLY 4HIS MEANS TAKING THE BEAN FROM THE REUSABLE COMPONENT STAGE TO BEING PART OF AN APPLICATION &OR SIMPLE BEANS THAT MIGHT MEAN SIMPLY WRITING A CLIENT THAT CAN ACCESS THE BEAN IE CALL THE BEANS BUSINESS METHODS )N OTHER WORDS A SINGLE BEAN MIGHT BE THE ENTIRE APPLICATION ON THE SERVER SIDE "UT THIS COULD ALSO BE THE STEP WHERE YOU INTEGRATE MULTIPLE BEANS AND OTHER *AVA CLASSES INTO A CUSTOM APPLICATION AND THAT USUALLY MEANS TAKING DIFFERENT BEANS EACH IN ITS OWN EJB JAR WITH ITS OWN $$ AND PUTTING THEM INTO A NEW SINGLE EJB JAR WITH A SINGLE $$ THAT MIGHT DESCRIBE HOW TWO OR MORE BEANS ARE RELATED TO ONE ANOTHER $URING ASSEMBLY YOU MIGHT ALSO ADD NEW INFORMATION TO THE $$ FOR THINGS THE BEAN DEVELOPER DIDNT KNOW ABOUT &OR EXAMPLE THE BEAN DEVELOPER MIGHT WRITE CODE THAT USES A SPECIAL BEAN SPECIlC hPROPERTYv CALLED AN ENVIRONMENT ENTRY WHICH WELL GET INTO IN A LATER CHAPTER FOR THE TAX AMOUNT USED BY THIS APPLICATION "UT THE BEAN DEVELOPER HAS NO IDEA WHAT VALUE TO GIVE THE TAX AMOUNT PROPERTY SO HE LEAVES THE VALUE BLANK IN THE $$ 4HEN THE APPLICATION ASSEMBLER COMES ALONG SEES BY READING THE $$ THAT THE BEAN USES A PROPERTY lGURES OUT WHAT THE VALUE SHOULD BE AND ADDS IT TO THE $$ &OR THE !DVICE BEAN PUTTING THE BEAN IN THE EJB JAR BUILDING THE $$ AND DEPLOYING WILL HAPPEN AS ONE BIG STEP 5$EPLOYMENT 4HIS IS WHERE THE RUBBER MEETS THE ROAD THE BEAN MEETS THE SERVER THE DEVELOPER MEETS THE SYS ADMIN 4HE TWO CRUCIAL PARTS OF DEPLOYMENT ARE NAMING THE BEAN SO THE CLIENT WILL KNOW HOW TO lND IT AND GETTING THE BEAN INTO THE CONTAINERS CONTROL 4HE SPEC DOESNT SAY ANYTHING ABOUT THE WAY IN WHICH YOU DEPLOY YOUR BEANS IT ALL DEPENDS ON THE %*" SERVERCONTAINER THAT YOURE USING
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 28
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<]\WZQIT" /HW·VPDNHGHSOR\DQGWHVWWKH$GYLFH%HDQ 7ELL WRITE THE CODE COMPILE IT START THE SERVER START THE DEPLOYTOOL USE THE DEPLOYTOOL TO MAKE THE $$ AND THE EJB JAR DEPLOY THE BEAN CREATE A CLIENT AND TEST THE BEAN USING THE CLIENT 4HE ONLY THING WE WONT DO IS INSTALL AND CONlGURE THE SERVER 7E ASSUME YOU ALREADY DID THAT )F YOU DONT YET HAVE THE *%% 2) UP AND RUNNING GO TO HTTPJAVASUNCOMJEE AND DOWNLOAD VERSION OF *%% IT INCLUDES SET UP INSTRUCTIONS THEN GO BACK AND DOWNLOAD THE *%% !0) DOCUMENTATION :K\DUHZHXVLQJ WKH5, ":K\FDQ·WZHXVH D5($/DSSVHUYHU"
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7ZOIVQbMaW]ZXZWRMK\LQZMK\WZa !LL THE BEANS IN THIS BOOK ARE ORGANIZED INTO PACKAGES WHICH MEANS YOU MUST BE A LITTLE MORE CAREFUL ABOUT COMPILING AND RUNNING %VERY INSTRUCTION IN THIS CHAPTER ASSUMES YOUVE ORGANIZED YOUR PROJECT EXACTLY THE WAY ITS SHOWN HERE )F YOU DEVIATE FROM THIS STRUCTURE YOURE ON YOUR OWN FOR MAPPING OUR COMMAND LINE AND DEPLOYMENT FORMULAS TO YOUR OWN STRUCTURE 7KHUH·VRQO\21(SURMHFWV GLUHFWRU\IRUWKHZKROH ERRN
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 1. Welcome to EJB
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Page 30
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+ WUXQTM\PM\ _WQV\MZNIKM[ IVL\PMJMIVKTI[[ 3O FAR WEVE WRITTEN THE TWO INTERFACES AND THE BEAN CLASS BUT WE STILL HAVE TO COMPILE THEM !FTER THAT WELL MAKE THE EJB JAR WHICH HOLDS CLASS l LES NOT SOURCE l LES
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7ERE USING THE G COMPILER m AG SO THE COMMAND LINE ABOVE SAYS h#OMPILE ALL THE JAVA l LES IN THE @HEADl RST DIRECTORY AND THEN PUT THE COMPILED CLASS l LES INTO THE @CLASSES DIRECTORY WHICH YOULL l ND BY GOING UP ONE LEVEL FROM THE CURRENT SRC DIRECTORY /H YEAH ALMOST FORGOT BE SURE TO PUT THE CLASSES IN THEIR CORRECT 0!#+!'% DIRECTORY ,OOK FOR THE PACKAGE STRUCTURE INSIDE THE @CLASSES DIRECTORY WHICH MEANS YOU SHOULD SEE A DIRECTORY NAMED @HEADl RST AND 4(!4S WHERE THE CLASS l LES NEED TO GOAND IF YOU DO ./4 l ND THE @HEADl RST DIRECTORY THERE THEN MAKE ONE FOR ME 4HANKSv
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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;\IZ\\PM[MZ ^MZ /PEN UP A NEW TERMINAL FOR THE SERVER 9OULL LEAVE IT RUNNING AND WE WANT TO SEE THE OUTPUT AS IT RUNS SO DONT USE THIS TERMINAL FOR ANYTHING ELSE -AKE THE ADVICE DIRECTORY YOUR WORKING DIRECTORY )LOH(GLW:LQGRZ+HOS%ODK%ODK%ODK
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 1. Welcome to EJB
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VWDUWLQJGHSOR\WRRO
;\IZ\LMXTWa\WWT /PEN UP A NEW TERMINAL FOR THE DEPLOYTOOL 4HIS TOOL IS PART OF THE *%% 2) AND IT HAS EVERYTHING YOU NEED TO CREATE THE EJB JAR THE $$ AND TO DO THE lNAL DEPLOYMENT INTO THE 2) SERVER )LOH(GLW:LQGRZ+HOS&KLOO
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aW]¼TT[MM[WUM\PQVOTQSM\PQ[ ! LOVELY SPLASH SCREEN POPS UP AND SITS WHILE THE APPLICATION LOADS )F YOU CLICK THE SPLASH SCREEN IT DISAPPEARS SO DONT PANIC IF IT THEN LOOKS LIKE NOTHINGS HAPPENING 0ATIENCE
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 33
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5ISMIVM_)XXTQKI\QWV 4HE 2) IS A *%% SERVER REMEMBER NOT JUST AN %*" CONTAINER 3O WE HAVE TO DO A SMALL BIT OF *%%ISH STUFF BEFORE WE CAN MAKE THE EJB JAR AND DEPLOY THE APP 4HIS STEP IS WHERE WE CREATE A NEW *%% APPLICATION AND FOR NOW YOU CAN THINK OF THE *%% APPLICATION AS SOMETHING THAT WRAPS THE BEANS AND ADDS A LITTLE MORE INFORMATION FOR THE SERVER 4HE MAIN DIFFERENCE BETWEEN A *%% APPLICATION AND AN %*" APPLICATION IS THAT A *%% APPLICATION CAN INCLUDE WEB COMPONENTS SERVLETS AND *30S AS WELL AS %*" COMPONENTS ALL INTEGRATED AS PART OF A SINGLE APP &KRRVH)LOH 1HZ$SSOLFDWLRQ
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.O 7ITH A *%% SERVER THE WEB COMPONENTS AND %*" COMPONENTS ARE MORE TIGHTLY INTEGRATED WHICH MEANS YOU CAN HAVE ALL OF THE COMPONENTS RESPECT ONE ANOTHERS TRANSAC TIONS AND SECURITY "UT YOURE ALWAYS FREE TO USE A SERVLET AS A CLIENT TO AN ENTERPRISE BEAN EVEN IF THAT BEAN ISNT RUNNING IN THE SAME APPLICATION SERVER OR EVEN THE SAME PHYSICAL MACHINE !NOTHER ADVANTAGE OF A *%% SERVER IS THE EASE WITH WHICH YOU CAN DEPLOY BOTH COMPONENT TYPES AS PART OF ONE ENTERPRISE APPLICATION (AVING SAID ALL THIS CHANCES ARE EXTREMELY HIGH THAT IF YOURE DO ING %*" APPLICATIONS YOU ARE RUNNING THEM IN A *%% SERVER 2EMEMBER THERE ARE VERY FEW STANDALONE %*" CONTAINERS TODAY 6IRTUALLY ALL SIGNIFICANT VENDORS RUN THEIR %*" CONTAINERS WITHIN A *%% SERVER
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 1. Welcome to EJB
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Page 34
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6IUMIVL[I^M\PMVM_IXXTQKI\QWV 4HIS PARTS A LITTLE AWKWARD 9OU CAN USE THE "ROWSE BUTTON TO NAVIGATE THROUGH YOUR OWN DIRECTORY TREE BUT THE EASIEST WAY TO NAME AND SAVE THE APPLICATION IS TO TYPE THE COMPLETE PATH TO THE lLE YOURE ABOUT TO CREATE 4HE THING WERE MAKING IS NOT THE BEAN ITSELFYOU CAN THINK OF IT MORE LIKE A DOCUMENT THAT HOLDS ALL THE INFORMATION ABOUT THE APPLICATION !S A CONVENTION WE SAVE THE APPLICATION IN THE PROJECTS;WHATEVER= DIRECTORYTHE DIRECTORY CORRESPONDING TO THAT PARTICULAR PROJECT &OR THE !DVICE BEAN THAT MEANS THE PROJECTS ADVICE DIRECTORY )F YOU STARTED THE SERVER FROM THE PROJECTSADVICE DIRECTORY IN OTHER WORDS IF ADVICE IS YOUR CURRENT WORKING DIRECTORY THEN YOULL GET THE RIGHT NAME AND LOCATION BY DEFAULT 1DPHWKHDSSOLFDWLRQ$GYLFH$SS ,IQHHGHGLQFOXGHWKHIXOOSDWKWRSURMHFWVDGYLFH$GYLFH$SS &OLFN2.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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?PI\aW]¼TT[MMIN\MZaW]KZMI\MIVLVIUM \PMIXXTQKI\QWV .OW YOURE BACK AT THE MAIN SCREEN OF THE DEPLOYTOOL 9OU MIGHT HAVE TO CLICK ON THE &ILES OR !PPLICATIONS ICONS TO EXPAND THEM BUT YOULL SEE THAT THE TOOL HAS CREATED AN !PPLICATIONS DIRECTORY WITH SOMETHING CALLED !DVICE!PP INSIDE #LICK ON THE !DVICE!PP ICON AND YOULL SEE INFORMATION ABOUT THE APPLICATION INCLUDING THE NAME LOCATION AND CURRENT CONTENTS !T THIS POINT THERES NOTHING BUT A -%4! ).& DIRECTORY THAT HOLDS MORE INFO ABOUT THE APP WHICH WE WONT EVER NEED TO LOOK AT
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 1. Welcome to EJB
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GHSOR\WRRO PDNLQJDQHZHQWHUSULVHEHDQ
6W_TM\¼[UISM\PMVM_MV\MZXZQ[M JMIV\PMMRJRIZIVL\PM,, 4HIS IS WHAT WERE REALLY AFTERTHE ACTUAL BEAN 4HE PREVIOUS STEPS MAKING THE *%% APPLICATION WERE TO SATISFY THE *%% 2) BECAUSE WE HAVE TO DEPLOY THE BEAN WITHIN A *%% APP &KRRVH)LOH1HZ(QWHUSULVH%HDQ
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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6W__M¼ZMQV\PMZMITTaKWWT 6M_-V\MZXZQ[M*MIV?QbIZL 4HIS PART OF THE DEPLOYTOOL IS WHERE ALMOST EVERYTHING HAPPENS 4HE KEY THINGS WELL DO ARE 5 #REATE THE EJB JAR 5 0UT THE BEAN CLASS AND THE TWO INTERFACES INTO THE EJB JAR 5 #REATE THE DEPLOYMENT DESCRIPTOR THAT DESCRIBES THE BEAN
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 1. Welcome to EJB
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GHSOR\WRRO FUHDWHDQHZHMEMDU
+ZMI\M\PMVM_MRJRIZ &OR NOW JUST ACCEPT THE DEFAULTS 4HE RADIO BUTTON ON THE TOP LEFT OF THE SCREEN SHOWS THAT YOURE MAKING A NEW *!2 WITHIN THE !DVICE!PP APPLICATION .OTICE THAT THE !DVICE!PP IS PART OF A DROP DOWN LISTIF THERE WERE OTHER EJB JARS ALREADY IN THE APPLICATION WE COULD HAVE CHOSEN TO PUT THE NEW BEAN IN A PRE EXISTING *!2 4HE TOOL PICKS AN ESPECIALLY HELPFUL DISPLAY NAME h%JBv AND YOULL SEE THIS BACK ON THE MAIN DEPLOYTOOL SCREEN WHEN WERE DONE 4HAT NAME ISNT USED ANYWHERE IN YOUR REAL APPLICATION SO ITS NO BIG DEAL BUT IF YOU HAVE MORE THAN ONE *!2 IN AN APPLICATION YOU MIGHT WANT TO GIVE IT A MORE DESCRIPTIVE NAME #ART *!2 !CCOUNT *!2 ETC
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 1. Welcome to EJB
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Page 39
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)LL\PM\PZMMKTI[[NQTM[QVKT]LQVO\PMQZ XIKSIOMLQZMK\WZa\W\PM2): 4HIS IS THE MOST IMPORTANT PART OF THE WHOLE PROCESS )N OTHER WORDS DONT SCREW IT UP 4HE KEY IS TO GET THE CORRECT CLASSES INTO THE *!2 IN THEIR PACKAGE DIRECTORY STRUCTURE AND ONLY THEIR PACKAGE DIRECTORY STRUCTURE )N OTHER WORDS IF YOU PUT THE THREE CLASS lLES INTO THE *!2 WITHOUT THE HEADlRST DIRECTORY YOUR BEAN WONT DEPLOY /R IF YOU INCLUDE THE CLASSES DIRECTORY AS WELL AS THE HEADlRST DIRECTORY YOUR BEANS WONT DEPLOY 2EMEMBER THE EJB JAR IS STILL A *!2 lLE SO THE USUAL *!2 RULES ABOUT PACKAGE STRUCTURES APPLY HERE 1DYLJDWHWRWKH$GYLFHGLUHFWRU\ ([SDQGWKHFODVVHVGLUHFWRU\WRVHHWKHKHDGÀUVWGLUHFWRU\ 6HOHFWWKHKHDGÀUVWGLUHFWRU\ &OLFN$GG
Use the navigation controls here to get to your Advice directory where you can see your, classes and src direct Then select the headÞorirstes. directory. You donÕt to expand it... we didhave it so that you could see whatÕs in there.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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GHSOR\WRRO FRQ¿UP-$5FRQWHQWV
+WVNQZU\PI\aW]ILLML764A\PM XIKSIOMLQZMK\WZaIVL\PMKTI[[NQTM[ 9OU GOTTA GET THIS PART RIGHT ,OOK AT THE BOTTOM WINDOW THAT SAYS h#ONTENTS OF %JBv AND VERIFY THAT THE ONLY THING IN THE *!2 BESIDES THE -%4! ).& DIRECTORY IS THE HEADlRST DIRECTORY INCLUDING THE CONTENTS OF THE DIRECTORY 4HE CLASSIC MISTAKE WE SEE ALL THE TIME NOT THAT YOUD EVER DO THAT IS TO ADD ONLY THE CLASS lLES BUT NOT THE PACKAGE DIRECTORY "E SURE THAT YOU HAVE THE HEADlRST DIRECTORY AND NOT THE CLASSES DIRECTORY WITH THE THREE CLASS lLES !NOTHER COMMON MISTAKE IS TO ADD THE SOURCE lLES INSTEAD OF THE CLASS lLES 3O DONT FEEL BAD IF IT HAPPENS TO YOU 9HULI\WKDW\RXKDYHWKHULJKWFODVVHV DQGSDFNDJHGLUHFWRU\ ,I\RXGRQ¶WVHOHFWWKHPIURPWKHERWWRPZLQGRZFOLFN5HPRYHDQGVWDUWRYHU &OLFN2.ZKHQ\RX¶UHGRQHWKHQFOLFN1(;7
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 1. Welcome to EJB
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5ISMQ\I;\I\MTM[[;M[[QWVJMIV .OW WERE AT THE PLACE WHERE WE GIVE THE TOOL THE BEANS @STRUCTURAL INFORMATION 7HAT KIND OF BEAN IT IS WHICH CLASS lLE IS THE HOME INTERFACE AND SO ON 2EMEMBER THE TOOL USES THIS TO CREATE THE DEPLOYMENT DESCRIPTOR !ND THE %*" CONTAINER USES THE DEPLOYMENT DESCRIPTOR TO lGURE OUT HOW TO DEPLOY AND MANAGE THE BEAN 4HE !DVICE BEAN IS SIMPLECLIENT CALLS A METHOD ON THE REMOTE OBJECT THE REMOTE OBJECT RETURNS A VALUE THEN THE REMOTE OBJECT FORGETS THE WHOLE THING EVER HAPPENED %ND OF STORY 4HAT SCENARIO IS JUST PERFECT FOR A STATELESS SESSION BEAN SOLUTION )F THE !DVICE BEAN NEEDED TO REMEMBER THE ADVICE IT GAVE TO THE CLIENT AND USE IT IN SOME WAY IN FUTURE INVOCATIONS FROM THAT SAME CLIENT THEN WED MAKE IT STATEFUL "UT WE DONT SO WE WONT !ND AS YOULL LEARN LATER IT WOULDNT MAKE SENSE TO HAVE THE !DVICE BEAN BE AN ENTITY OR MESSAGE DRIVEN BEAN "UT ITS TOO LATE TO MAKE IT ANYTHING BUT A SESSION BEAN ANYWAYYOUR BEAN CLASS IMPLEMENTS THE 3ESSION"EAN INTERFACE 3O YOURE ALREADY COMMITTED TO A BEAN TYPE "UT WHETHER THE SESSION BEAN IS STATELESS OR STATEFUL CAN BE A LITTLE MORE SUBTLE &OR NOW JUST MAKE IT STATELESS 6HOHFWWKH6HVVLRQUDGLREXWWRQ 6HOHFWWKH6WDWHOHVVUDGLREXWWRQ
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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>MZQNaM^MZa\PQVOWV\PQ[[KZMMV #HOOSING THE BEAN CLASS THE HOME INTERFACE AND THE COMPONENT INTERFACE IS A PERMANENT DECISION /NCE YOURE DONE WITH THE REST OF THE BEAN WIZARD AND THE DEPLOYMENT DESCRIPTOR IS CREATED YOURE STUCK WITH IT )F YOU ACCIDENTALLY MIX UP THE HOME AND COMPONENT INTERFACES YOUR BEAN WONT WORK )N THE 2) IT WONT EVEN DEPLOY SOME SERVERS LET YOU DEPLOY STRUCTURALLY BAD BEANS WHICH MEANS THEY BLOW UP AT RUNTIME BUT THE 2) WONT EVEN LET YOU IN THE SERVER DOOR %HVXUH\RXKDYHWKHIROORZLQJVHWWLQJV (QWHUSULVH%HDQ&ODVV KHDGÀUVW$GYLFH%HDQ 5HPRWH+RPH,QWHUIDFH KHDGÀUVW$GYLFH+RPH 5HPRWH,QWHUIDFH KHDGÀUVW$GYLFH &OLFN1(;7
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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AW]¼ZMLWVMKTQKS.QVQ[P "ECAUSE THIS BEAN IS SO SIMPLE AND WE DONT CARE ABOUT TRANSACTIONS SECURITY ENVIRONMENT ENTRIES AND DATABASE ACCESS WEVE DONE EVERYTHING WE NEED TO MAKE THE DEPLOYMENT DESCRIPTOR AND PUT IT IN A *!2 WITH THE CLASS lLES 3O YOU CAN IGNORE THE 4RANSACTIONS -ANAGEMENT SCREEN ALTHOUGH YOULL BECOME INTIMATE WITH IT LATER IN THE BOOK &OLFN)LQLVK
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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GHSOR\WRRO PDLQVFUHHQDIWHUPDNLQJDEHDQ
5MIV_PQTMJIKSWV\PMUIQVLMXTWa\WWT[KZMMV 4HINGS HAVE CHANGED 4HE !DVICE!PP ICON EXPANDS TO SHOW YOUR EJB JAR NAMED h%JBv AND THE EJB JAR EXPANDS TO SHOW THE CUTE BEAN ICON NAMED h!DVICE"EANv )F YOU SELECT THE !DVICE"EAN YOULL SEE A BUNCH OF TABBED PANELS THATLL SHOW YOU THE CHOICES YOU MADE IN THE BEAN WIZARD 3OME OF THE THINGS YOU CHOSE CAN BE CHANGED BUT SOME CANT )N THE 'ENERAL PANEL FOR EXAMPLE YOU CANT CHANGE THE CLASS lLE DESIGNATIONS FOR THE HOME COMPONENT AND BEAN )N FACT YOU CAN SEE THAT THE DROP DOWN LISTS FOR THESE ARE GRAYED OUT HERE "UT GEE YOU CAN STILL CHANGE IT FROM 3TATELESS TO 3TATEFUL
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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:]VaW]ZJMIV\PZW]OP\PMLMXTWa\WWT^MZQNQMZ 9OU ALREADY KNOW YOUR BEAN CLASSES COMPILE BUT JUST BECAUSE IT COMPILES DOESNT MEAN IT FOLLOWS BEAN LAW 4HE VERIlER TAKES YOUR JAR AND RUNS IT THROUGH A BUNCH OF TESTS TO SEE IF IT MEETS THE MINIMUM REQUIREMENTS FOR DEPLOYMENT !S YOU LEARN MORE ABOUT THE %*" SPEC YOULL SEE THAT THE VERIlER IS TESTING YOUR BEANS CODE AND THE DEPLOYMENT DESCRIPTOR TO SEE IF IT COMPLIES WITH THE SPEC &OR EXAMPLE A STATELESS SESSION BEANS HOME INTERFACE MUST HAVE A NO ARG CREATE METHOD DECLARED AND NOTHING ELSE !ND THE BEAN CLASS MUST HAVE METHODS THAT MATCH THOSE DECLARED IN THE COMPONENT INTERFACE !ND IF THE COMPONENT INTERFACE IS REMOTE IT MUST DECLARE THAT EACH METHOD THROWS 2EMOTE%XCEPTION $ONT WORRY ABOUT REMEMBERING THESE EXAMPLES ITS JUST TO GIVE YOU AN IDEA OF THE KINDS OF THINGS THE VERIlER DOES &OLFNRQWKH(MELFRQ WKHOLWWOHMDU WRKLJKOLJKWLW &KRRVH7RROV 9HULÀHU &URVV\RXU¿QJHUV
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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+TW[MaW]ZMaM[IVLKTQKS73 4HE VERIlER SCREEN SHOWS YOU THE NAME OF THE *!2 AS EJB JAR ICJAR IN A TMP DIRECTORY BUT THATS JUST HOW THE 2) SAVES YOUR EJB JAR UNTIL YOURE READY TO DEPLOY 4HE TMP lLE AND THE *!2 WILL GO AWAY WHEN YOU DEPLOY OR DELETE THE BEAN FROM YOUR APPLICATION !T LEAST ITS SUPPOSED TO 3OMETIMES YOU MIGHT HAVE TO lND THAT DIRECTORY AND DELETE IT YOURSELF 2EPEAT AFTER ME 4HE DEPLOYTOOL IS FREE 4HE DEPLOYTOOL IS NOT A PRODUCTION TOOL ) DID NOT PAY ANY MONEY FOR THIS TOOL ) WILL LEARN TO APPRECIATE ITS STRENGTHS AND LOOK PAST THE WAYS IT IS A PAIN IN THE A
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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?PM_ 6WNIQTML\M[\[ )F EVERYTHING VERIlES YOU SEE A NICE LITTLE MESSAGE IN THE $ETAILS BOX AT THE BOTTOM OF THE VERIlER WINDOW )F THERE ARE FAILURES YOULL SEE THEM IN THE 2ESULTS BOX 9OU CAN CLICK ON A @FAILURE MESSAGE TO GET MORE DETAILS ABOUT WHAT WENT WRONG $ONT PANIC IF YOU SEE A MILLION FAILURES USUALLY YOU CAN lX ONE THING AND THEY ALL GO AWAY 5NLIKE COMPILER ERROR MESSAGES WHICH ARE SOMETIMES ABOUT AS HELPFUL AS 6#2 INSTRUCTIONS THE VERIlER FAILURE MESSAGES ARE PRETTY EXPLICIT 9OU CAN USUALLY lGURE OUT EXACTLY WHERE YOU WENT WRONG 3OMETIMES YOU CAN lX THE PROBLEM BACK IN THE MAIN DEPLOYTOOL WINDOW BY CLICKING ON ONE OF THE TABBED PANELS AND CHANGING SOMETHING &OR EXAMPLE IF YOU FORGOT TO SPECIFY A TRANSACTION ATTRIBUTE FOR AN ENTITY BEAN METHOD YOU CAN GO TO THE 4RANSACTIONS TABBED PANEL IN THE DEPLOYTOOL WINDOW AND SET THE ATTRIBUTE WITHOUT STARTING OVER IN THE BEAN WIZARD "UT IF YOU HAVE PROBLEMS WITH YOUR ACTUAL CLASS lLES YOULL HAVE TO MODIFY THEM RECOMPILE THEM AND THEN UPDATE YOUR EJB JAR /R IF THE PROBLEM IS THAT YOU MADE A SETTING IN THE BEAN WIZARD THAT CANT BE CHANGED LIKE SELECTING THE BEAN CLASS WHEN THE TOOL ASKS FOR THE HOME INTERFACE YOULL HAVE TO DELETE THE EJB JAR AND START OVER WITH THE BEAN WIZARD %HKDSS\DERXWWKHZRQGHUIXOPHVVDJHDWWKHERWWRP &OLFN&ORVH
Click Close to put away the window. If you click OK, youÕll just run the veriÞer again.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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5ISMQ\:M\]ZVI+TQMV\2IZ /NCE IT STARTS THE SERVER IS GOING TO DO A TON OF THINGS TO GET YOUR BEAN READY /NE OF THEM IS TO GENERATE THE CLASS lLES THAT IMPLEMENT YOUR TWO INTERFACES THE HOME AND THE COMPONENT INTERFACES !ND SINCE THEYRE REMOTE INTERFACES THE SERVER WILL ALSO CREATE THE REMOTE STUB CLASSES FOR THOSE INTERFACES ,OTS MORE ON THESE LATER 7ELL THE CLIENT NEEDS THE TWO INTERFACES AND THE TWO STUBS 9OU COULD HAVE GIVEN THE CLIENT THE INTERFACES SINCE YOU CREATED THOSE "UT ONLY THE SERVER CAN MAKE THE STUB CLASSES AND THE CLIENT WILL NEVER WORK WITHOUT THEM 3O YOUR CLIENT APPLICATION MIGHT BE SITTING THERE ALL NICE AND COMPILED AND JUST WAITING FOR YOU TO GIVE IT THE STUB CLASSES SO THAT IT CAN ACTUALLY RUN &ORTUNATELY YOU CAN ASK THE 2) DEPLOYTOOL TO GIVE YOU A CLIENT JAR THAT HAS EVERYTHING THE CLIENT NEEDS AND A LOT MORE IT TURNS OUT BUT SINCE THIS ISNT A REAL PRODUCTION ENVIRONMENT WERE JUST GOING TO LET THAT GO 6IRTUALLY ALL %*" APPLICATION SERVERS MUST CREATE THE STUB CLASSES SO YOULL HAVE TO lND OUT WHERE YOUR SERVER PUTS THEM SO YOU CAN GIVE THEM TO THE CLIENT 6HOHFWWKH5HWXUQ&OLHQW-DUFKHFNER[ SXWLWLQWKHSURMHFWVDGYLFHGLUHFWRU\ &OLFN1H[W!
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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/Q^MQ\IVIUM[WKTQMV\[KIVTWWSQ\]X 7ERE NOW DANGEROUSLY CLOSE TO DEPLOYMENT AND THE LAST STEP IS TO GIVE THE BEAN A *.$) NAME 4HATS THE NAME CLIENTS USE TO GET A REFERENCE TO THE BEAN 7ELL TO WHAT THE CLIENT THINKS IS THE BEAN BUT WELL SAVE THE GORY DETAILS FOR THE NEXT CHAPTER 4HE BEANS *.$) NAME IS SIMPLY THE LOGICAL NAME YOU CHOOSE OR IN THE REAL WORLD WHOEVER DEPLOYS THE BEAN )T DOESNT HAVE TO MATCH ANYTHING FROM THE BEAN ITSELF 7E COULD FOR EXAMPLE NAME THIS BEAN (OMER WHICH WOULD IN FACT MAKE IT EVEN MORE FUN AND CHALLENGING FOR THE CLIENTS THAN IT ALREADY WOULD BE WITH A MEANINGFUL NAME 7\SHLQWKH-1',QDPH$GYLVRU &OLFN)LQLVK 7DNHDGHHSEUHDWKDQGKROGLWXQWLOWKHGHSOR\SURFHVVFRPSOHWHV
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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?I\KP\PMXZWOZM[[JIZ[OW]X\PMVKMTMJZI\M 7AIT FOR IT WAIT FOR IT WAIT FOR IT 7HEN THE BEANS DEPLOYED SUCCESSFULLY YOULL SEE THE LINE h$EPLOYMENT OF !DVICE!PP IS COMPLETEv IN THE WINDOW !T THAT POINT CLIENTS CAN ACCESS THE BEAN 9OU DID IT &OLFN2.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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6W_aW]¼TT[MM\PM)L^QKM)XXQV[QLM\PM[MZ ^MZ 5NDER THE 3ERVERS ICON YOULL SEE THE LOCALHOST ICON REPRESENTING THE *%% SERVER YOU STARTED BEFORE YOU LAUNCHED THE DEPLOYTOOL !ND UNDER THE LOCALHOST ICON YOU CAN NOW SEE THAT YOUR !DVICE!PP IS DEPLOYED 9OULL ALSO SEE THE 5NDEPLOY BUTTON THAT YOU CAN USE TO WELL UNDEPLOY ([SDQGWKH6HUYHUV!ORFDOKRVWLFRQVWRVHHWKH$GYLFH$SS
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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6W_ITT_MVMMLQ[IKTQMV\ 7E HAVE A FRESHLY DEPLOYED BEAN IN A *%% SERVER BUT WE CANT TEST IT UNTIL WE HAVE A CLIENT 4HE CLIENT HAS TO DO lVE THINGS
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 1. Welcome to EJB Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 2. EJB Architecture
Table of Contents Chapter 2. EJB Architecture........................................................................ 1 Section 2.1. objectives Background................................................................................................................................................. 2 Section 2.2. You remember this picture......................................................................................................................................... 3 Section 2.3. Making a remote method call..................................................................................................................................... 4 Section 2.4. There's a "helper" on the server as well...................................................................................................................... 5 Section 2.5. There are no dumb questions..................................................................................................................................... 6 Section 2.6. What about and return values arguments?................................................................................................................ 7 Section 2.7. What really gets passed when you pass an object to a remote method?.................................................................... 9 Section 2.8. There are no Dumb Questions.................................................................................................................................. 12 Section 2.9. Passing a Remote object through a remote method call.......................................................................................... 14 Section 2.10. Brain power.............................................................................................................................................................. 15 Section 2.11. There are no Dumb Question................................................................................................................................... 17 Section 2.12. What must the Remote object and the stub have in common?.............................................................................. 19 Section 2.13. The client calls business methods on the stub through the Remote business interface....................................... 20 Section 2.14. Sharpen your pencil................................................................................................................................................. 21 Section 2.15. How EJB uses RMI.................................................................................................................................................. 22 Section 2.16. The Remote object is not the bean, it's the bean's bodyguard—the EJBObject .................................................... 23 Section 2.17. The Component interface........................................................................................................................................ 24 Section 2.18. There are no Dumb Questions................................................................................................................................ 26 Section 2.19. Who writes the class that really DOES implement the component interface? In other words, who makes the EJBObject class?........................................................................................................................................................................... 28 Section 2.20. Who creates what?.................................................................................................................................................. 29 Section 2.21. THE TIKIBEAN LOUNGE...................................................................................................................................... 30 Section 2.22. There are no Dumb Questions................................................................................................................................ 31 Section 2.23. Sharpen your pencil................................................................................................................................................ 37 Section 2.24. Architectural over view: Session beans.................................................................................................................. 39 Section 2.25. Architectural overview: Entity beans..................................................................................................................... 40 Section 2.26. Architectural overview : Creating a Stateful Session bean..................................................................................... 41 Section 2.27. Architectural overview: Creating a Stateless Session bean.................................................................................... 42 Section 2.28. Who creates the stateless session bean, and when?.............................................................................................. 43 Section 2.29. Stateless session beans are more scalable.............................................................................................................. 44 Section 2.30. Brain power............................................................................................................................................................. 45 Section 2.31. there are no Dumb Questions................................................................................................................................. 45 Section 2.32. Sharpen your pencil................................................................................................................................................ 45 Section 2.33. There are no Dumb Questions................................................................................................................................ 46 Section 2.34. Architectural over view: Message-driven beans..................................................................................................... 47 Section 2.35. Exercise: What goes where?................................................................................................................................... 48 Section 2.36. Exercise: Organize your beans................................................................................................................................ 49 Section 2.37. Exercise Solutions: What goes where?................................................................................................................... 50
Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Chapter 2. EJB Architecture
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 12
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2UNTIME 5SUALLY ANYWAY 2EMEMBER THAT THE DECLARED ARGUMENT OR RETURN TYPE IS NOT NECESSARILY THE SAME AS THE ACTUAL RUNTIME TYPE 4HE ONLY CASE WHERE IT CAN FAIL AT COMPILE TIME IS IF THE REMOTE METHOD ACTUALLY USES 3ERIALIZABLE AS THE DECLARED TYPE OF THE ARGUMENT OR RETURN VALUE SXEOLFYRLGWDNH,W 6HULDOL]DEOHV )N THAT CIRCUMSTANCE THE COMPILER CAN USE NORMAL *AVA TYPE CHECKING TO SEE IF THE DECLARED TYPE OF THE THING BEING PASSED IMPLEMENTS 3ERIALIZABLE -OST OF THE TIME THE DECLARED ARGUMENT OR RETURN TYPE IS SOMETHING OTHER THAN 3ERIALIZABLE LIKE $OG !RRAY,IST 3TRING ETC SO *AVA WONT KNOW WHETHER THE RUNTIME OBJECT IS 3ERIALIZABLE UNTIL IT ACTUALLY TRIES TO DO THE SERIALIZATION AND THEN IT THROWS AN EXCEPTION !ND WITH COLLECTIONS AND ARRAYS IF ANY OF THE OBJECTS INSIDE ARENT 3ERIALIZABLE THE WHOLE SERIALIZATION FAILS
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 2. EJB Architecture
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 14
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 15
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 16
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 17
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 21
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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0W_-2*][M[:51 )N %*" A CLIENTS ENTRY POINT INTO THE ENTERPRISE APPLICATION IS NEARLY ALWAYS THROUGH A REFERENCE STUB TO A 2EMOTE OBJECT 9ES IT IS POSSIBLE AND SOMETIMES NECESSARY TO USE A LOCAL CLIENT IE A CLIENT IN THE SAME HEAP AS THE BEAN AND WHICH DOESNT USE 2-) TO INVOKE BUSINESS METHODS BUT THIS IS FOR ONLY A FEW VERY SPECIAL CASES
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Page 23
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Page 24
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Page 25
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Page 26
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7HEN ONE INTERFACE EXTENDS ANOTHER IT INHERITS EVERYTHING FROM THAT INTERFACE 7HOEVER IMPLEMENTS AN INTERFACE MUST IMPLEMENT NOT JUST THE METHODS FROM THAT INTERFACE BUT ALSO THE METHODS FROM EVERY INTERFACE THAT INTERFACE EXTENDS ALL THE WAY UP THE INTERFACE INHERITANCE TREE 3O IN THIS EXAMPLE WHOEVER IMPLEMENTS "OOK#ART MUST ALSO IMPLEMENT THE METHODS OF %*"/BJECT
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
[email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 28
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2EMEMBER THE CONTAINER ISNT IMPLEMENTING THE REAL BUSINESS LOGIC 4HE TRUE FUNCTIONALITY FOR THOSE BUSINESS METHODS LIVES IN YOUR BEAN CLASSTHE CLASS THAT YOU IMPLEMENT 4HE CLASS IMPLEMENTING THE COMPONENT INTERFACE IS GOING TO BE THE %*"/BJECT 4HE BODYGUARD 4HE 2EMOTE OBJECT !ND REMEMBER THAT THE %*"/BJECT IS ONLY PRETENDING TO BE THE BEAN )T CAN RESPOND TO THE REMOTE METHOD CALLS COMING FROM THE CLIENT VIA THE STUB BUT THE %*"/BJECTS ONLY JOB IS TO CAPTURE THE INCOMING CLIENT CALLS TO THE BEAN !FTER THAT ITS UP TO THE CONTAINER SERVER TO TAKE OVER 7E DONT REALLY KNOW HOW THE %*"/BJECT IS IMPLEMENTEDITS COMPLETELY UP TO THE VENDOR "UT WE DONT REALLY CARE !LL YOU NEED TO KNOW IS THAT AN %*" CONTAINER IS REQUIRED BY THE SPEC TO GENERATE THE CODE FOR THE %*"/BJECT AND ITS CORRESPONDING STUB \RXDUHKHUH
Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Page 29
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID:
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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there are no
Dumb Questions
Q:
(OW AND WHEN DOES THE CONTAINER CREATE THE %*"/BJECT AND THE (OME AND THE STUBS
A:
7HEN YOU DEPLOY A BEAN THE CONTAINER LOOKS AT THE $$ AND TAKES IT FROM THERE 2EMEMBER THE $$ GIVES THE FULLY QUALIFIED NAME OF YOUR 2EMOTE #OMPONENT %*"/BJECT INTERFACE AND YOUR 2EMOTE (OME INTERFACE 3O ONCE THE CONTAINER GETS THOSE INTERFACES IT GENERATES CODE FOR THE TWO CLASSES IMPLEMENTING THOSE INTERFACES !ND BECAUSE THEYRE 2EMOTE THE CONTAINER ALSO CREATES THE CLIENT STUBS THAT KNOW HOW TO COMMUNICATE BACK TO THE 2EMOTE OBJECTS
Q:
!RE THESE ALWAYS PLAIN OLD 2-) STUBS ) SEE THAT WHEN WE DEPLOYED USING THE 2) IT PRINTED OUT A MESSAGE THAT IT WAS RUNNING RMIC
A:
4HE CONTAINER CAN DO WHAT EVER IT WANTS TO CREATE THE STUBS THE REQUIREMENT IS THAT THE STUBS BE 2-) ))/0 COMPLIANT )N FACT A SERVER CAN USE SOMETHING CALLED DYNAMIC PROXIES TO IMPLEMENT THE STUB FUNCTIONAL ITY BUT WE DONT CARE 7HEN WE SAY hSTUBv WE MEAN SOMETHING WITH STUB BEHAVIOR 7HETHER ITS AN 2-) STUB OR SOMETHING ELSE IS AN IMPLEMENTATION DETAIL FOR THE SERVER 7ELL LOOK AT THAT IN MORE DETAIL IN THE NEXT CHAPTER 4HE BOTTOM LINE IS THAT YOU REALLY DONT KNOW WHAT THE STUB CLASS CODE LOOKS LIKE &OR THAT MATTER YOU REALLY DONT KNOW HOW THE %*"/BJECT AND THE (OME ARE IMPLEMENTED 9OURE NOT SUPPOSED TO KNOW 9OU MIGHT HAVE AN %*" CONTAINER THAT
LETS YOU VIEW POSSIBLY EVEN HACK THE GENERATED SOURCE CODE BUT DONT COUNT ON IT !ND IF WE WERE YOU WE JUST WOULDNT GO THERE EVEN IF WE COULD
Q:
3O THESE CLASSES ARE UP TO THE VENDORS IMPLEMENTATION
A:
9ES 4HE VENDOR HAS ALL SORTS OF CHOICES FOR IMPLEMENTING THESE CLASSES AND MIGHT USE THE STUBS AND OR (OME AND %*"/BJECTS TO GET SOME PERFORMANCE ADVANTAGES "UT AGAIN THATS NOT UP FOR YOU TO MESS WITH OR EVEN KNOW ABOUT 4HE ONLY REQUIREMENT IN THE SPEC THAT YOURE GUARANTEED AND REQUIRED TO ADHERE TO IS THAT 2EMOTE OBJECTS MUST FOLLOW THE RULES FOR 2-) ))/0 WHICH MEANS *AVAS 2EMOTE -ETHOD )NVOCATION USING THE ))/0 #/2"! STANDARD WIRE PROTOCOL
Q:
9OU BROUGHT IT UP HOW IS 2-) ))/0 DIFFERENT FROM REGULAR 2-)
A:
0LAIN OLD 2-) USES *2-0 AS ITS WIRE PROTOCOL "UT ))/0 LETS 2EMOTE OBJECTS INTEROPERATE THROUGH #/2"! WE WONT BE SAYING MUCH AT ALL ABOUT #/2"! IN THIS BOOK ITS DEFINITELY OUT OF SCOPE FOR THE EXAM AND THE BOOK EXCEPT IN A FEW TINY CASES WELL SEE SCATTERED THROUGHOUT THE CHAPTERS 4HAT GIVES YOUR OBJECTS A CHANCE TO BE ACCESSED FOR EXAMPLE BY EVEN NON *AVA CLIENTS /NE THING ))/0 SPECIFIES IS THE WAY INFORMATION FOR TRANSACTIONS AND SECURITY CAN BE PROPAGATED ALONG WITH THE METHOD CALL AND YOUR CONTAINER MIGHT BE TAKING ADVANTAGE OF THAT
&OR THE MOST PART YOULL BARELY NOTICE THE DIFFERENCE BETWEEN PLAIN OLD 2-) AND 2-) ))/0 "UT THERE ARE A COUPLE OF PLACES WHERE ITS DIFFERENT AND ONE OF THESE DIFFERENCES IS DEFINITELY ON THE EXAMTHE NEED TO NARROW A STUB 7ELL COVER NARROWING IN DETAIL IN THE NEXT CHAPTER ON #LIENT 6IEW &OR NOW JUST KNOW THAT ITS SOMETHING A CLIENT MUST DO WITH AN %*" STUB THAT THEY DONT HAVE TO DO WITH A PLAIN *AVA STUB BECAUSE THE %*" SPEC TELLS YOU TO ASSUME THAT THE STUB IS USING ))/0 AND THUS MIGHT BE A DIFFERENT KIND OF STUB
Q:
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A: Q:
.EXT PAGE
7HY DID YOU TAKE SO LONG )SNT THE (OME IMPORTANT
A:
!S CRUCIAL AS THE (OME IS ITS USUALLY JUST THE WAY YOU GET A REFERENCE TO SOMETHING THAT IMPLEMENTS THE #OMPONENT INTERFACE )N OTHER WORDS YOU USE THE (OME TO GET AN %*"/BJECT STUB FOR 2EMOTE CLIENTS WHICH IS ALL WEVE TALKED ABOUT SO FAR &OR %NTITY BEANS THE (OME CAN HAVE A MORE IMPORTANT ROLE AND WELL SEE THAT BUT EVEN WITH %NTITY BEANS THE (OMES PRIMARY USE IS STILL TO GET %*"/BJECT STUBS !FTER THAT MOST OF THE COMMUNICATION BETWEEN THE CLIENT AND THE BEAN COMES THROUGH THE %*"/BJECT AND NOT THE (OME -OST OF THE TIME IN FACT CLIENTS USE THE (OME JUST TO GET THE %*"/BJECT REFERENCE AND THEN THE (OME REFERENCE IS TOSSED OUT NOT NEEDED
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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The client calls create() on the Home stub (create() is a method in the Home interface).
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The EJBObject is created/instantiated for the bean.
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The EJBObject stub is returned to the client, so the client can call business methods on the Component interface.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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The client calls create() on the Home stub (create() is a method in the Home interface).
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An EJBObject is created for this client.
The bean stays in the bean pool ! It comes out only to service an actual business method, if the client invokes one on the EJBObject stub.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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?PWKZMI\M[\PM[\I\MTM[[[M[[QWV JMIVIVL_PMV' &IRST WE HAVE TO DElNE WHAT CREATE MEANS &OR A SESSION BEAN IT MEANS THE BEAN INSTANCE IS PHYSICALLY INSTANTIATED AND INITIALIZED AS A BEAN &OR AN ENTITY BEAN ITS COMPLETELY DIFFERENT SO THIS CONVERSATION APPLIES JUST TO SESSION BEANS ,ATER WELL GET INTO WHAT IT MEANS TO CREATE AN ENTITY BEAN &OR STATEFUL SESSION BEANS THE CREATE IS TRIGGERED BY THE CLIENT 4HE CLIENT CALLS CREATE ON A (OME STUB AND EVERYTHING HAPPENS AT THAT POINTAN %*"/BJECT IS INSTANTIATED FOR THIS NEW ABOUT TO BE CREATED BEAN AND THEN THE BEAN ITSELF IS CREATED AND LINKED TO THE %*"/BJECT THE BEANS BODYGUARD "UT FOR STATELESS SESSION BEANS THE CLIENT CREATE AND THE ACTUAL CREATION OF THE BEAN ARE DECOUPLED )N OTHER WORDS JUST BECAUSE THE CLIENT CALLS CREATE ON A (OME STUB DOESNT MEAN A BEAN WILL BE CREATED AT THAT POINT 3TATELESS SESSION BEANS ARENT CREATED UNTIL THE CONTAINER DECIDES IT NEEDS ONE AND THATS REALLY UP TO THE CONTAINER )T MIGHT FOR EXAMPLE MAKE A BUNCH OF BEAN INSTANCES IE CREATE SOME BEANS AND PLOP THEM IN A POOL BEFORE EVEN A SINGLE CLIENT HAS ASKED FOR ONE BY CALLING CREATE ON A (OME STUB /R THE CONTAINER MIGHT MAKE JUST IN TIME BEANS AND WAIT UNTIL THE CLIENT INVOKES A BUSINESS METHOD BEFORE GOING TO THE TROUBLE OF PHYSICALLY CREATING THE BEAN
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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The bean comes out of the pool ONLY when a client invokes a business method on the EJBObject stub. So, a single bean can jump out to handle one clientÕs call, then jump back in the pool, then jump out to handle a different clientÕs call, and then jump back in the pool... \RXDUHKHUH
Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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!CTUALLY THAT REALLY PISSES US OFF TOO "UT YOULL GET USED TO IT "E THANKFUL IT WAS EVEN WORSE IF YOU LEARNED %*" PRIOR TO VERSION WHEN IT WAS CALLED THE (OME AND THE 2EMOTE .OW THAT WAS A REAL PROBLEM BECAUSE FIRST OF ALL BOTH THE (OME AND THE 2EMOTE WERE 2EMOTE IN THE JAVARMI SENSE 3ECOND AS OF %*" YOU CAN HAVE A (OME AND A 2EMOTE THAT ARENT ACTUALLY 2EMOTE 3O THEY HAD TO CHANGE THE NAME TO #OMPONENT INTERFACE INSTEAD OF CALLING IT 4(% 2EMOTE INTERFACE SINCE IT MIGHT IN FACT NOT BE 2EMOTE )F YOU JUST REMEMBER THAT THE #OMPONENT INTERFACE IS WHERE THE BUSINESS METHODS ARE AND THE (OME IS WHERE THE UM (OME METHODS ARE YOU SHOULD BE FINE *UST REMEMBER #OMPONENT BUSINESS %*"/BJECT OR %*",OCAL/BJECT BUT WE WONT GO THERE UNTIL THE NEXT CHAPTER
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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3ORT OF ! STATELESS SESSION BEAN DOESNT NEED A BODYGUARD UNTIL HES ACTUALLY INVOLVED IN A METHOD INVOCATION 3O THE CLIENT GETS A REFERENCE TO AN %*"/BJECT BUT THE BEAN ISNT ASSOCIATED WITH THAT %*"/BJECT UNTIL THE CLIENT CALLS A BUSINESS METHOD !T THAT POINT THE BEAN SLIDES OUT OF THE POOL TO SERVICE THE METHOD 3O THE %*"/BJECT THE CLIENT HAS IS FOR A KIND OF BEAN !DVICE"EAN 7EATHER"EAN ETC BUT NOT A SPECIFIC INSTANCE OF A BEAN
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(AVE YOU ALREADY THOUGHT ABOUT THIS IN THE "RAIN 0OWER ON THE PREVIOUS PAGE "ECAUSE IF YOU HAVENT DONT READ ANY FURTHER UNTIL YOUVE COME UP WITH YOUR OWN IDEAS )F YOU
MADE IT THIS FAR WE ASSUME THAT YOU ALREADY KNOW THE ANSWER AND WERE JUST CONFIRMING IT ! STATEFUL BEAN REMEMBER HOLDS CLIENT CONVERSATIONAL STATE 4HAT MEANS THE BEAN HAS TO SAVE CLIENT SPECIFIC STATE IN OTHER WORDS IT HAS TO REMEMBER THINGS ABOUT THIS CLIENT ACROSS MULTIPLE METHOD INVOCATIONS FROM THE CLIENT
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/NLY FOR THE LIFE OF THE SESSION ! SESSION CONTINUES UNTIL THE CLIENT TELLS THE BEAN HES DONE BY CALLING REMOVE ON THE BEANS #OMPONENT INTERFACE OR THE SERVER CRASHES OR THE BEAN TIMES OUT WELL COVER THAT IN THE 3ESSION LIFECYCLE CHAPTER
4HINK OF A SHOPPING CART AGAINA STATEFUL BEAN NEEDS TO REMEMBER WHATS IN THE CLIENTS CART EACH TIME THE CLIENT CALLS ADD)TEM4O#ART ! STATELESS BEAN ON THE OTHER HAND DOESNT HAVE 3O STATEFUL SESSION BEANS TO REMEMBER ANYTHING ON THE CLIENTS ARENT SCALABLE BEHALF SO TO A CLIENT ONE STATELESS BEAN OF A PARTICULAR TYPE IS AS GOOD AS ANY OTHER BEAN OF THAT TYPE .O THEY ARE *UST NOT AS SCALABLE )F THE !DVICE"EAN SIMPLY RETURNS AS STATELESS BEANS A PIECE OF ADVICE NOT CONNECTED IN ANY WAY TO ANYTHING IT TOLD THE CLIENT BEFORE OR ANYTHING THE CLIENT TOLD IT THEN THERES NO NEED FOR THE (OW CAN A STATEFUL BEAN BE !DVICE"EAN TO BE STATEFUL )N THAT CASE SCALABLE IF YOU ALWAYS NEED ONE BEAN EACH TIME A CLIENT CALLS GET!DVICE FOR EVERY CLIENT ON THE #OMPONENT INTERFACE IE THE %*"/BJECT ANY !DVICE"EAN IS JUST AS CAPABLE OF RUNNING THE METHOD AS ANY 9OU DO NEED A SEPARATE BEAN OTHER ALLOCATED FOR EACH CLIENT BUT NOT EVERY /N THE OTHER HAND IF THE !DVICE"EAN BEAN HAS TO BE ACTIVELY CONSUMING WERE MODIFIED TO RETURN SAY RANDOM RESOURCES )F THE STATEFUL SESSION BEAN BUT NON REPEATING ADVICE THEN THE CLIENT IS TAKING A LONG TIME BETWEEN !DVICE"EAN WOULD HAVE TO BE STATEFUL METHOD CALLS THE STATEFUL BEAN CAN SO THAT IT COULD KEEP TRACK OF PREVIOUS BE TEMPORARILY TAKEN DOWN AND PUT ADVICE AND NEVER REPEAT IT IN A STATE CALLED PASSIVATION 4HIS STATE PRESERVES THE CLIENT SPECIFIC STATE OF COURSE BUT REDUCES THE NUMBER OF BEANS CURRENTLY ALIVE IN THE SERVER 4HE BEAN COMES OUT OF PASSIVATION AND BACK INTO ACTIVE DUTY ACTIVATION WHEN THE CLIENT CALLS A BUSINESS METHOD
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 2. EJB Architecture Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 3. Exposing Yourself
Table of Contents Chapter 3. Exposing Yourself...................................................................... 1 Section 3.1. Objectives..................................................................................................................................................................... 2 Section 3.2. What the client really wants........................................................................................................................................ 3 Section 3.3. It all starts with the home interface............................................................................................................................ 4 Section 3.4. There are no Dumb Questions.................................................................................................................................... 4 Section 3.5. How a client uses a session bean: create, use, and remove........................................................................................ 5 Section 3.6. But first, we have to get a home interface reference.................................................................................................. 6 Section 3.7. What's JNDI?.............................................................................................................................................................. 6 Section 3.8. Getting the home interface stub................................................................................................................................. 7 Section 3.9. There are no Dumb Questions.................................................................................................................................... 8 Section 3.10. Let's take another look at the complete client code.................................................................................................. 9 Section 3.11. Sharpen your pencil................................................................................................................................................... 9 Section 3.12. Just when you thought a simple cast would be enough.......................................................................................... 10 Section 3.13. But NO. You have to narrow the object as well!...................................................................................................... 10 Section 3.14. OK, I'll bite. Why can't you just do a plain old cast ?.............................................................................................. 10 Section 3.15. PortableRemoteObject.narrow().............................................................................................................................. 11 Section 3.16. Think of narrowing as "Exotic Casting".................................................................................................................. 12 Section 3.17. Now that we (finally) have the home stub, let's use it to get what we REALLY want............................................ 13 Section 3.18. There are no Dumb Questions................................................................................................................................. 14 Section 3.19. Writing the Remote home interface for a session bean.......................................................................................... 15 Section 3.20. Remote home interface examples for session beans.............................................................................................. 16 Section 3.21. If you're a client, and you want to........................................................................................................................... 19 Section 3.22. Sharpen your pencil................................................................................................................................................ 22 Section 3.23. But enough about the home... let's talk about the EJB object. The component interface. The thing you REALLY want............................................................................................................................................................................................... 23 Section 3.24. Imagine what else you might want to do with your EJB object reference............................................................. 25 Section 3.25. Online shopping should not be rushed.................................................................................................................. 28 Section 3.26. Thankfully, we've got handles................................................................................................................................. 29 Section 3.27. isIdentical ?: how to find out if two stubs refer to the same bean.......................................................................... 31 Section 3.28. There are no Dumb Questions................................................................................................................................ 33 Section 3.29. A bean's client interfaces can be local .................................................................................................................... 35 Section 3.30. BRAIN POWER....................................................................................................................................................... 35 Section 3.31. Sharpen your pencil................................................................................................................................................. 37 Section 3.32. Which methods make sense for the local client interfaces?.................................................................................. 38 Section 3.33. When you think handle , think Remote.................................................................................................................. 39 Section 3.34. Who needs EJBMetaData when you've got reflection?.......................................................................................... 39 Section 3.35. Do you need isIdentical() when there's equals() ?................................................................................................. 40 Section 3.36. Why so many remove methods?............................................................................................................................. 41 Section 3.37. How can you use a remove that takes a handle when you don't have a handle?................................................... 43 Section 3.38. There are no Dumb Questions................................................................................................................................ 43 Section 3.39. Comparing Remote vs. Local interfaces................................................................................................................. 44 Section 3.40. Sharpen your pencil................................................................................................................................................ 45 Section 3.41. Writing the local client interfaces........................................................................................................................... 46 Section 3.42. You can have both a Remote and local client view for a bean, but you probabl won't.......................................... 47 Section 3.43. Sharpen your pencil................................................................................................................................................ 48 Section 3.44. Exceptions in client interfaces: what the client might get..................................................................................... 49 Section 3.45. Local client code...................................................................................................................................................... 50 Section 3.46. BRAIN POWER: What has to change inside the bean class?................................................................................. 51 Section 3.47. Arguments to Remote vs. local methods................................................................................................................ 53 Section 3.48. There are no Dumb Questions................................................................................................................................ 54 Section 3.49. Exercise: BE the Container..................................................................................................................................... 55 Section 3.50. Exercise Solutions: BE the Container..................................................................................................................... 57 Section 3.51. COFFEE CRAM....................................................................................................................................................... 58 Section 3.52. COFFEE CRAM....................................................................................................................................................... 60
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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9OURE SHOPPING )TS TOUGH BECAUSE YOU CANT DECIDE WHETHER YOURE A SPRING OR A SUMMER 9OU DONT WANT TO BE RUSHED BUT YOUVE ALREADY GOT A BUNCH OF STUFF IN YOUR CART WHEN YOU REALIZE YOURE l VE MINUTES LATE FOR WORK
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HY CANT YOU JUST USE THE EQUALS METHOD INSTEAD OF IS)DENTICAL )SNT THAT WHAT EQUALS IS FOR
A:
2EMEMBER WERE TALKING ABOUT 2EMOTE OBJECTS 4HE EQUALS METHOD COMPARES TWO OBJECTS ON THE SAME (%!0 WHERE IS)DENTICAL COMPARES TWO 2EMOTE OBJECTS ON THE 3%26%2
Q:
) STILL DONT SEE WHY THEY COULDNT HAVE JUST IMPLEMENTED THE EQUALS METHOD ON THE STUB TO DO THE SAME THING
A:
4HE EQUALS METHOD IS NOT A REMOTE METHOD FOR ONE THING 9OU CAN ALWAYS CALL EQUALS ON A STUB BECAUSE YOU CAN CALL IT ON ANY OBJECT ON YOUR HEAP "UT ITS NOT PART OF THE REMOTE INTERFACE SO IT CANT BE A REMOTE METHOD FOR EXAMPLE IT DOESNT DECLARE A 2EMOTE%XCEPTION ETC
!ND REMEMBER THE EQUALS METHOD IS USED TO SEE IF TWO OBJECTS ON THE HEAP ARE MEANINGFULLY EQUIVALENT 4HE VENDOR CAN IMPLEMENT THE EQUALS METHOD ON THE STUB ANY WAY IT LIKES BUT THAT STILL DOESNT TELL YOU ANYTHING ABOUT WHATS GOING ON BACK AT THE SERVER END *UST BECAUSE TWO STUBS DONT PASS THE EQUALS TEST DOESNT MEAN THE SERVER DOESNT CONSIDER THE TWO %*" OBJECTS TO BE IDENTICAL OR REFERENCING IDENTICAL BEANS 9OUR SERVER MAY BE USING 2-) STUBS FOR EXAMPLE THAT HAVE NO LOGIC FOR HOW THEIR COMPARISONS RELATE TO MEANINGFUL COMPARISONS OF TWO %*" OBJECTS ON THE SERVER 2-) STUBS KNOW ABOUT 2EMOTE OBJECTS BUT THEY DONT KNOW WHAT THOSE 2EMOTE OBJECTS REPRESENT
Q:
(OW COME THERES A METHOD IN THE %*"/BJECT INTERFACE FOR GETTING THE BEANS HOME )F YOU DONT (!6% THE HOME THEN HOW DID YOU GET THE BEAN IN THE lRST PLACE
A:
4HERE ARE OTHER WAYS TO GET A REFERENCE TO AN %*" OBJECT )TS TRUE THAT YOU CANT USE *.$) TO LOOK UP THE %*" OBJECT ONLY THE HOME IS REGISTERED "54 THERES NOTHING TO STOP YOU FROM PASSING AN %*" OBJECT REFERENCE AS AN ARGUMENT OR RETURN VALUE 9OU MIGHT HAVE A BUSINESS METHOD IN ONE BEAN WHOSE SOLE JOB IS TO HAND YOU BACK A REFERENCE TO AN %*" OBJECT FOR A DIFFERENT BEAN .OW SUPPOSE YOU HAVE THIS %*" OBJECT REFERENCE TO A BEAN WHOSE HOME YOU NEVER HAD AND NOW YOU WANT TO MAKE MORE OF THOSE BEANS FOR YOURSELF 9OU CAN DO THAT BY ASKING FOR THE BEANS HOME USING GET%*"(OME !ND EVEN IF YOU DO HAVE ENOUGH INFORMATION TO DO A LOOKUP IN *.$) FOR THAT BEANS HOME *.$) LOOKUPS ARE EXPENSIVE 9OULL SAVE SOME OVERHEAD IF YOU JUST GET THE HOME REFERENCE FROM THE BEAN DIRECTLY
Q:
7HY CANT YOU SERIALIZE THE STUB 7HY DO WE NEED HANDLES
A:
7E DIDNT SAY THE STUB WASNT 3ERIALIZABLE "UT EVEN IF YOU CAN SERIALIZE IT THAT DOESNT MEAN ITS GOT ENOUGH INFORMATION TO GET YOU BACK TO THE SAME OR MEANINGFULLY IDENTICAL %*" OBJECT 7HEN THE STUB COMES OVER FROM THE SERVER ITS ALREADY KNOWLEDGEABLE ABOUT HOW TO CONTACT A PARTICULAR 2EMOTE OBJECT 7HEN THAT STUB IS RECREATED THAT EXACT 2EMOTE OBJECT MIGHT NOT EVEN EXIST ANY LONGER
Q: A:
4HEN HOW WOULD THE HANDLE BE ANY BETTER
4HE HANDLE HAS THE @SMARTS TO COMMUNICATE WITH THE SERVER AND GET BACK SOMETHING THAT IS JUST THE SAME AS THE %*" OBJECT YOU HAD BEFORE )N OTHER WORDS IT MIGHT NOT BE THE SAME %*" OBJECT BUT THE CLIENT WILL NEVER BE ABLE TO TELL THE DIFFERENCE \RXDUHKHUH
Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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)JMIV¼[KTQMV\QV\MZNIKM[KIVJMTWKIT 7EVE LOOKED AT ONLY THE 2EMOTE CLIENT INTERFACES FOR A BEAN SO FAR BUT AS OF %*" SESSION AND ENTITY BEANS CAN EXPOSE A LOCAL CLIENT VIEW )N OTHER WORDS CLIENT INTERFACES THAT DO NOT EXTEND JAVARMI2EMOTE 7HAT DOES THIS MEAN 4HAT THE HOME OBJECT AND %*" OBJECT ARE NOT 2EMOTE OBJECTS 4HEYRE RUNNING IN THE SAME *6- AS THE CLIENT AND THE BEAN )N THE ENTITY BEAN #-2 CHAPTER WELL LOOK AT WHY LOCAL INTERFACES WERE ADDED TO THE SPEC &OR NOW THINK OF THEM AS A VERY SPECIAL CASE
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 38
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ORFDOLQWHUIDFHV
?PQKPUM\PWL[UISM[MV[MNWZ\PMTWKITKTQMV\QV\MZNIKM[' 9OU ALREADY KNOW THAT THE LOCAL CLIENT INTERFACES ARE MISSING SOME OF THE METHODS FROM THEIR 2EMOTE COUNTERPARTS ,ETS lGURE OUT WHICH ONES ARE MISSING AND WHY
,W_MVMMLPIVLTM[_Q\PTWKITQV\MZNIKM[' 2EMEMBER WHY HANDLES EXIST IN %*"TO GIVE YOU A 3ERIALIZABLE OBJECT THAT YOU CAN USE TO RE ESTABLISH A STUB TO THE %*" OBJECT YOUD BEEN WORKING WITH 4HE HANDLE IS JUST AN ABSTRACTION OF A REMOTE CONNECTION 3O DOES THIS MAKE SENSE ON A LOCAL CLIENT
,W_MVMML-2*5M\I,I\I_Q\PTWKITQV\MZNIKM[' 2EMEMBER WHAT %*"-ETA$ATA IS USED FORTO GET REmECTION LIKE INFO ABOUT A BEAN )F YOU CALL GET%*"-ETA$ATA ON A BEANS 2EMOTE HOME YOU GET BACK AN OBJECT THAT IMPLEMENTS %*"-ETA$ATA 4HAT INTERFACE %*"-ETA$ATA HAS METHODS THAT LET YOU INTERROGATE THE BEAN AND LEARN MORE ABOUT THE CLASSES THAT MAKE UP THE COMPONENT 7OULD A LOCAL CLIENT EVER NEED %*"-ETA$ATA
,W_MVMMLQ[1LMV\QKIT_Q\PTWKITQV\MZNIKM[' 2EMEMBER WHY IS)DENTICAL EXISTSTO LET YOU COMPARE TWO HOME OR COMPONENT INTERFACE REFERENCES TO SEE IF THEY REFER TO hMEANINGFULLY EQUIVALENTv BEANS ON THE SERVER 7OULD YOU NEED TO USE IS)DENTICAL ON A LOCAL CLIENT "IG (INT THE SERVER IS FREE TO IMPLEMENT EQUALS ANY WAY IT CHOOSES
,W_MVMMLXZQUIZaSMaQVNWZUI\QWV_Q\PTWKITQV\MZNIKM[' 2EMEMBER WHY PRIMARY KEYS EXISTTO UNIQUELY IDENTIFY ENTITY BEANS 7OULD YOU EVER NEED TO IDENTIFY AN ENTITY BEAN ON A LOCAL CLIENT
,W_MVMMLZMUW^MUM\PWL[_Q\PTWKITQV\MZNIKM[' 2EMEMBER WHAT REMOVE IS USED FORTO TELL THE CONTAINER THAT YOURE DONE WITH A BEAN FOR 3ESSION BEANS OR TO TELL THE CONTAINER TO PERMANENTLY DELETE THE ENTITY FOR ENTITY BEANS 7OULD A LOCAL CLIENT NEED TO CALL REMOVE ON A BEAN
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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,WaW]VMMLQ[1LMV\QKIT_PMV\PMZM¼[MY]IT[ ' 4WKITKTQMV\[[\QTTVMMLQ[1LMV\QKIT 2EMEMBER FOR A 2EMOTE CLIENT THE ONLY LOCAL COMPARISON YOU DO IS ON TWO STUB OBJECTS USING EQUALS 4HIS DOESNT WORK WHEN YOU WANT TO COMPARE SOMETHING BACK ON THE SERVER IN THIS CASE THE TWO %*" OBJECT REFERENCES 4HATS WHAT IS)DENTICAL IS FOR "UT LOCAL CLIENTS HAVE THE REAL THING 4HEY HAVE THE REAL REFERENCE TO THE %*" OBJECT SO THEY CAN USE EQUALS TO SEE IF TWO %*" OBJECT LOCAL REFERENCES ARE MEANINGFULLY EQUIVALENT "UT THATS STILL NOT WHAT YOU WANT 4HERE IS NO GUARANTEE IN THE SPEC FOR THE RESULTS YOULL GET WITH EQUALS 3O WHILE IT SEEMS LIKE YOU COULD JUST USE EQUALS RATHER THAN IS)DENTICAL WITH A LOCAL CLIENT THE SPEC DOES NOT GUARANTEE THAT THE RESULTS WILL BE THE SAME "OTTOM LINE IF YOU WANT TO KNOW IF TWO %*" OBJECT REFERENCES ARE REFERENCING THE SAME SESSION OBJECT YOU HAVE TO USE IS)DENTICAL EVEN WHEN THE %*" OBJECT IS LOCAL 5(027(FOLHQWYLHZ
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 41
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?Pa[WUIVaZMUW^MUM\PWL[' .WZ:MUW\MKTQMV\[\ _WQV\PMPWUMXT][WVMQV\PM KWUXWVMV\QV\MZNIKM 2EMEMBER 2EMOTE CLIENTS HAVE THREE REMOVE METHODS AVAILABLE TWO IN THE HOME AND ONE IN THE COMPONENT INTERFACE 4HE REMOVE THAT COMES FROM %*"/BJECT IS SIMPLE IF YOU CALL IT YOURE SAYING YOU WANT TO REMOVE THAT VERY BEAN )N OTHER WORDS THE BEAN WHOSE %*"/BJECT YOU USED TO CALL REMOVE !ND FOR SESSION BEANS REMEMBER CALLING REMOVE SIMPLY TELLS THE CONTAINER THAT YOURE DONE WITH THE BEAN )TS GOOD MANNERS AND IT IMPROVES SCALABILITY SINCE THE SERVER CAN STOP KEEPING CLIENT SPECIl C RESOURCES ON YOUR BEHALF RATHER THAN WAITING SAY FOR YOUR SHOPPING SESSION TO TIME OUT FROM INACTIVITY "UT THINGS ARENT SO SIMPLE WHEN YOU CALL REMOVE ON A HOME &OR ONE THING YOU ACTUALLY CANT REMOVE A HOME 4HE SERVER KEEPS THE BEAN HOME ALIVE WHETHER YOURE AROUND OR NOT SO THERES NO SIGNIl CANT CLIENT SPECIl C RESOURCES 4HERES NO NEED TO TELL THE SERVER YOURE DONE WITH THE HOME BECAUSE THE SERVER WOULD SIMPLY SAY h3O WHAT v 4HEN WHAT DOES IT MEAN TO CALL REMOVE ON A HOME )T MEANS YOURE TELLING THE HOME TO REMOVE ONE OF THE BEANS THAT CAME FROM THAT HOME !ND THAT MEANS YOU HAVE TO IDENTIFY WHICH BEAN YOURE TALKING ABOUT
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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)F LOCAL HOME INTERFACES DONT HAVE HANDLES THEN THERES NO WAY YOU COULD HAVE A REMOVE METHOD THAT TAKES A HANDLE "ECAUSE IN ORDER TO PASS A HANDLE TO THE HOME THAT UNIQUELY IDENTIlES THE BEAN YOURE TRYING TO REMOVE YOUD HAVE TO lRST GET THE BEANS HANDLE !ND SINCE LOCALLY EXPOSED BEANS DONT HAVE HANDLES YOU SEE THE PROBLEM
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4ELL ME AGAIN WHY YOU CANT REMOVE THE HOME
4HERES NEVER A REASON TO REMOVE THE HOME IN OTHER WORDS TO TELL THE CONTAINER YOURE DONE WITH IT BECAUSE THE CONTAINER MUST KEEP THE HOME AROUND WITH OR WITHOUT YOUR INTEREST 3O IF YOU WERE ABLE TO SAY REMOVE TO THE HOME THE CONTAINER WOULD SAY h'EEDONT FLATTER YOURSELF BUDDY 7HAT ) DO HERE ON THE SERVER IS NOT !"/54 YOU ) COULD CARE LESS WHEN YOURE DONE WITH YOUR HOME REFERENCEv
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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?ZQ\QVO\PMTWKITKTQMV\QV\MZNIKM[ .OW THAT WEVE COVERED WHAT THE CLIENT SEES IN A LOCAL INTERFACE LETS LOOK AT YOUR RESPONSIBILITY AS A "EAN 0ROVIDER )N OTHER WORDS WHAT YOU HAVE TO DO TO WRITE THE LOCAL INTERFACES FOR YOUR BEAN
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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AW]KIVPI^MJW\PI:MUW\M IVLTWKITKTQMV\^QM_NWZIJMIV J]\aW]XZWJIJTa_WV¼\ 7E MENTIONED EARLIER THAT LOCAL INTERFACES ARE A VERY SPECIAL CASE FOR A CLIENT VIEW 4HEY WERE INTRODUCED WITH VERSION OF THE %*" SPEC WHICH THIS BOOK IS BASED ON AND THE ORIGINAL INTENT WAS TO SUPPORT CONTAINER MANAGED RELATIONSHIPS IN ENTITY BEANS "UT ENOUGH CUSTOMERS AND VENDORS ASKED FOR THE ABILITY TO HAVE NON 2EMOTE INTERFACES FOR BEANS SO THE *%% TEAM DECIDED TO MAKE IT AVAILABLE FOR SESSION BEANS AS WELL AS ENTITY BEANS "UT REGARDLESS OF WHICH YOU CHOOSE ITS VERY UNLIKELY YOULL HAVE A DESIGN THAT REQUIRES BOTH A LOCAL AND 2EMOTE CLIENT VIEW )F YOUR BEAN IS IN A CONTAINER MANAGED RELATIONSHIP WITH ANOTHER ENTITY BEAN YOULL LEARN ALL ABOUT THIS IN THE ENTITY CHAPTERS YOU HAVE NO CHOICE 4HE BEAN MUST EXPOSE ITSELF LOCALLY !ND IN THAT CASE ITS ALMOST IMPOSSIBLE TO THINK OF A REASON TO ALSO HAVE THAT SAME BEAN EXPOSED TO 2EMOTE CLIENTS FOR OTHER PURPOSES *UST KNOW THAT IT IS LEGAL TO HAVE BOTH "UT YOU CAN NEVER EVER EVER MIX AND MATCH ! 2EMOTE HOME INTERFACE CAN GIVE OUT ONLY 2EMOTE COMPONENT INTERFACE REFERENCES IN OTHER WORDS A STUB TO THE 2EMOTE %*"/BJECT ! LOCAL HOME CAN GIVE OUT ONLY LOCAL COMPONENT INTERFACE REFERENCES IN OTHER WORDS A REGULAR *AVA HEAP REFERENCE TO THE %*",OCAL/BJECT
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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-`KMX\QWV[QVKTQMV\QV\MZNIKM["_PI\\PMKTQMV\UQOP\OM\ ! 2EMOTE INTERFACE MUST HAVE 2EMOTE%XCEPTION DECLARED ON EVERY METHOD 4HAT MEANS THE CLIENT USING A 2EMOTE INTERFACE MUST DEAL WITH 2EMOTE%XCEPTION FOR EVERY 2EMOTE METHOD CALL "UT LOCAL INTERFACES DONT HAVE THAT RESTRICTION 4HE ONLY METHODS IN A LOCAL CLIENT INTERFACE THAT MUST DECLARE EXCEPTIONS ARE THE CREATE AND REMOVE METHODS FOR SESSION BEANS ENTITY BEANS ALSO HAVE A lNDER METHOD THAT DECLARES A &INDER%XCEPTION 7E HAVE A WHOLE CHAPTER DEVOTED TO EXCEPTIONS IN %*" SO WE WONT GO INTO THE DETAILS NOW BUT THE ESSENCE IS THIS IF A BEAN OR THE #ONTAINER GENERATES A RUNTIME EXCEPTION 2EMOTE CLIENTS SEE THE EXCEPTION AS A CHECKED 2EMOTE%XCEPTION BUT LOCAL CLIENTS SEE IT AS AN UNCHECKED %*"%XCEPTION )N ADDITION TO WHATEVER OTHER CHECKED EXCEPTIONS CALLED APPLICATION EXCEPTIONS IN %*" THE INTERFACE METHODS DECLARE ALL 2EMOTE INTERFACE METHODS CAN THROW A 2EMOTE%XCEPTION AND LOCAL CLIENT INTERFACE METHODS CAN ALWAYS THROW AN %*"%XCEPTION 3O 2EMOTE CLIENTS MUST WRAP ALL CALLS TO A HOME OR COMPONENT INTERFACE METHOD IN A TRYCATCH WHILE LOCAL CLIENTS USE A TRYCATCH ONLY IF THE INTERFACE METHOD DECLARES AN APPLICATION EXCEPTION WHICH INCLUDES #REATE%XCEPTION 2EMOVE%XCEPTION &INDER%XCEPTION AND ANY OTHER EXCEPTIONS THE "EAN 0ROVIDER DECLARES IN THE METHODS OF THE BEANS CLIENT INTERFACES
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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4WKITKTQMV\KWLM #OMPARE THIS TO THE CODE MODIlCATIONS YOU MADE ON THE PREVIOUS SHARPEN 4O HELP SHOW THAT THE CALLS TO THE HOME AND COMPONENT INTERFACE ARE NO LONGER 2EMOTE WEVE MADE THE EXCEPTION HANDLING MORE lNE GRAINED .OTICE THAT WERE NOT CATCHING A 2EMOTE%XCEPTION LPSRUWMDYD[QDPLQJ LPSRUWKHDG¿UVW LPSRUWMDYD[HME
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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YiX`e gfn\i ?PI\PI[\WKPIVOMQV[QLM\PMJMIVKTI[[' 7EVE SEEN HOW THE INTERFACES CHANGE AND HOW THE CLIENT CODE HAS TO CHANGE WHEN YOU GO FROM A 2EMOTE TO LOCAL CLIENT VIEW "UT WHAT ABOUT THE BEAN CLASS ITSELF 7HAT DO YOU THINK $OES THE BEAN CODE NEED TO CHANGE IF YOURE GOING TO DEPLOY IT WITH A LOCAL CLIENT VIEW INSTEAD OF A 2EMOTE CLIENT VIEW 7HAT IF YOU PLAN TO DEPLOY IT WITH BOTH A LOCAL AND 2EMOTE CLIENT VIEW &OR NOW LETS ASSUME THAT THE ONLY METHOD THAT MATTERS IS THE BEANS BUSINESS METHOD (ERES HOW IT LOOKS IN THE ORIGINAL BEAN CLASS SXEOLF6WULQJJHW$GYLFH ^ 6\VWHPRXWSULQWOQ ³LQJHWDGYLFH´ LQWUDQGRP LQW 0DWKUDQGRP DGYLFH6WULQJVOHQJWK UHWXUQDGYLFH6WULQJV>UDQGRP@ `
$O YOU SEE ANYTHING IN THAT METHOD THAT LOOKS SPECIlC TO A 2EMOTE CLIENT VIEW 7OULD YOU NEED TO DO ANYTHING DIFFERENT WITH A LOCAL CLIENT .O DONT THINK SO !NYTHING THAT WORKS AS A RETURN TYPE OR ARGUMENT FOR A 2EMOTE METHOD IS GUARANTEED TO WORK FOR A LOCAL METHOD AS WELL SO WERE /+ THERE +IND OF A NO BRAINER WHEN THE RETURN TYPE IS 3TRING THOUGH /+ THERE IS ONE EXCEPTIONREMEMBER ACCORDING TO "EAN LAW YOU MUST NOT RETURN A BEANS 2EMOTE INTERFACE FROM A LOCAL INTERFACE METHOD 3O IT LOOKS LIKE AT LEAST WITH THIS BEAN WE SHOULD NEVER HAVE TO KNOW OR CARE 7E SHOULD BE ABLE TO DEPLOY THE BEAN AS WRITTEN AND THE BEAN SHOULD BE KEPT UNAWARE OF WHETHER ITS CLIENTS ARE 2EMOTE OR LOCAL 3OUNDS GOOD DOESNT IT 3IMPLE CLEAN OBJECT ORIENTED "UT THINK ABOUT IT SOME MORE )MAGINE A BEAN WITH MORE COMPLEX LOGIC -ORE BUSINESS METHODS !RGUMENTS TO THOSE METHODS !RGUMENTS THE METHOD MIGHT EVEN NEED TO ACT ON (MMMMM CAN YOU THINK OF ANYTHING THAT THE BEAN MIGHT WANT TO TREAT DIFFERENTLY IF IT KNEW THE CLIENT WERE LOCAL INSTEAD OF 2EMOTE
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Q:
3O )M STILL NOT CLEAR IF THE BEAN -534 ALWAYS KNOW IF THE CLIENT IS 2EMOTE OR LOCAL
A:
)TS NOT THAT THE BEAN MUST BUT RATHER THAT THE BEAN MIGHT HAVE TO KNOW )F IT MATTERS THAT THE BEAN IS WORKING ON A THE CALLERS OBJECT VIA A COPY OF THE CALLERS REFERENCE AS OPPOSED TO A COPY OF THE CALLERS OBJECT YOUR BEAN CODE MIGHT HAVE TO CHANGE !ND THAT GOES FOR RETURN VALUES TOO )F IT MATTERS THAT THE CALLING METHOD GETS BACK A COPY OF A REFER ENCE VS A COPY OF AN OBJECT THE BEAN CODE MIGHT HAVE TO CHANGE
Q:
"UT ) THOUGHT THAT CHOOSING TO DEPLOY A BEAN WITH LOCAL VS 2EMOTE CLIENT VIEWS WAS JUST A MATTER OF SWITCHING A SWITCH AT DEPLOY TIME
A:
./ ./ ./ ,ETS IMAGINE THAT YOU DID WRITE TWO SETS OF INTERFACES ONE FOR A LOCAL CLIENT VIEW AND ONE FOR A 2EMOTE CLIENT VIEW )T IS TRUE THAT AT DEPLOYMENT YOU COULD DECIDE WHICH OF THE TWO VIEWS YOU WANTED TO EXPOSE OR BOTH "UT THAT WORKS ONLY IF THE BEAN CODE DOESNT CARE WHERE THE CLIENT IS ! BEAN METHOD WITH NO ARGUMENTS OR RETURN VALUES MIGHT BE SAFE REGARDLESS OF HOW THE CLIENT IS ACCESSING IT /NE SOLUTION MIGHT BE TO WRITE THE BEAN CODE ASSUMING THE BEAN IS ALWAYS GETTING A COPY AND THEN IF THE CLIENT IS LOCAL HAVE THE CLIENT MAKE A COPY CLONE OF THE OBJECT BEFORE PASSING IT /R FOR RETURN VALUES YOU MIGHT ALWAYS HAVE THE BEAN MAKE A COPY BEFORE HANDING IT BACK 4HAT WAY
THE BEAN NEVER HAS TO WORRY THAT A LOCAL CLIENT MIGHT BE MODIFYING THE BEANS OBJECT
!ND A LOCAL CLIENT WONT HAVE CODE TO HANDLE THE 2EMOTE%XCEPTIONS OR NARROW THE STUBS
Q:
4HE BOTTOM LINE IS THAT DEPLOYING A BEAN WITH A 2EMOTE VS LOCAL CLIENT VIEW IS A "IG $EAL )TS A COMMITMENT 4HE CLIENT HAS TO KNOW IN ADVANCE
4HEN ITS JUST ABOUT ARGUMENTS AND RETURN VALUES )S THERE ANY OTHER REASON YOU COULDNT DEPLOY A BEAN AND MAKE THE DECISION FOR 2EMOTE VS LOCAL VIEW AT DEPLOY TIME
A:
4HERE IS ANOTHER REASON 4HE CLIENT CODE %VEN IF THE BEAN DOESNT NEED TO KNOW HOW ITS CLIENT IS ACCESSING IT THE CLIENT MUST KNOW ! CLIENT WRITTEN TO ACCESS A BEAN LOCALLY WOULDNT WORK IF THE BEANS 2EMOTE CLIENT INTERFACES AND VICE VERSA
Q: A:
7HY NOT
4HE CLIENT MUST KNOW IN ADVANCE WHETHER ITS ACCESSING A BEANS 2EMOTE OR LOCAL CLIENT VIEW BECAUSE THE INTERFACES THEMSELVES ARE DIFFERENT 0OLYMORPHICALLY YOU CANT USE THE 2EMOTE AND LOCAL VIEWS INTERCHANGEABLY BECAUSE THE INTERFACES THEMSELVES ARE DIFFERENT 4HERES NO WAY THE CLIENT CAN BE KEPT BLISSFULLY IGNORANT BECAUSE THE BEHAVIOR OF THE BEAN IS DIFFERENT 2EMEMBER A 2EMOTE CLIENT MUST HANDLE 2EMOTE%XCEPTIONS AND NARROW THE 2EMOTE STUB COMING BACK FROM THE LOOKUP !ND A 2EMOTE CLIENT IS EXPOSED TO METHODS IN THE BEANS CLIENT INTERFACESMETHODS THAT DONT EXIST IN THE LOCAL INTERFACES 3O A 2EMOTE CLIENT MIGHT FOR EXAMPLE TRY TO CALL A GET(ANDLE METHOD ON THE LOCAL COMPONENT INTERFACE A METHOD CALL THAT WOULD NEVER WORK
Q:
#AN YOU GET AROUND THIS BY DECLARING YOUR 2EMOTE%XCEPTIONS ON YOUR LOCAL INTERFACE !ND COULD YOU MAKE AN INTERFACE THAT IS BOTH 2EMOTE AND LOCAL BY HAVING YOUR COMPONENT INTERFACE LIKE !DVICE EXTEND BOTH 2EMOTE AND %*",OCAL/BJECT 7HATS THE HARM IF THE CLIENT SIMPLY ALWAYS HANDLES 2EMOTE%XCEPTIONS AND ALWAYS DOES THE NARROW 4HAT WAY THE CLIENT SHOULDNT HAVE TO KNOW
A:
3TILL WONT WORK &OR ONE THING ACCORDING TO BEAN LAW YOURE NOT ALLOWED TO DECLARE 2EMOTE%XCEPTIONS ON LOCAL METHODS 3O THERES NO GUARANTEE THAT YOUR SERVER WOULD EVEN LET YOU DEPLOY A BEAN WITH A LOCAL INTERFACE THAT DECLARES 2EMOTE%XCEPTIONS !ND THERE IS NO GUARANTEE THAT THE NARROW METHOD WOULD NOT CAUSE PROBLEMS !ND THEN THERE ARE HANDLES AND ALL THAT OTHER STUFF 9OU NEED TO JUST LET THIS GO
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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remote Advice() is hea t ge r! ro er Compiler t it isnÕt handling t last line method, bu ption. If we moved theork. ce w x ld eE wou Remot try block, it INSIDE the
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 58
FRIIHHFUDPPRFNH[DP
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7HICH CAPABILITIES ARE PROVIDED BY BOTH REMOTE AND LOCAL HOME INTERFACES FOR SESSION BEANS #HOOSE ALL THAT APPLY
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2
7HEN LOCATING A SESSION BEANS REMOTE HOME INTERFACE WHICH ARE STEPS THAT MUST OCCUR TO CREATE A VALID HOME INTERFACE REFERENCE #HOOSE ALL THAT APPLY
R! 4HE SESSION CONTEXT MUST BE NARROWED AND THE NARROWED RESULT CAST R" 4HE RESULT OF THE *.$) LOOKUP MUST BE NARROWED AND THE NARROWED RESULT CAST
R# 4HE INITIAL CONTEXT MUST BE NARROWED AND THE NARROWED RESULT CAST R$ 4HE RESULT OF THE *.$) LOOKUP MUST BE CAST TO AN INITIAL CONTEXT AND THENNARROWED
3
'IVEN A REMOTE CLIENT @2 THAT HAS VALID REFERENCES TO SESSION BEANS @! AND @" AND GIVEN THAT ! IS A LOCAL CLIENT TO " WHICH STATEMENTS ARE TRUE #HOOSE ALL THAT APPLY
R! 2 CANNOT PASS HIS REFERENCE FOR ! TO " R" ! CANNOT PASS HIS REFERENCE FOR " TO 2 R# ! CANNOT INVOKE METHODS ON " R$ " CANNOT INVOKE METHODS ON 2
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 59
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WKHFOLHQWYLHZ
4
7HEN COMPARING TWO SESSION OBJECTS WHAT IS TRUE #HOOSE ALL THAT APPLY
R! 5SING THE IS)DENTICAL METHOD STATELESS SESSION BEANS FROM THE SAME HOME WILL ALWAYS RETURN TRUE
R" 5SING THE IS)DENTICAL METHOD STATEFUL SESSION BEANS FROM THE SAME HOME WILL ALWAYS RETURN TRUE
R# 4HE IS)DENTICAL METHOD CAN BE USED FOR ONLY REMOTE OBJECT REFERENCES
R$ 5SING THE EQUALS METHOD STATELESS SESSION BEANS FROM THE SAME HOME ARE GUARANTEED TO RETURN TRUE
R% 5SING THE EQUALS METHOD STATEFUL SESSION BEANS FROM THE SAME HOME ARE GUARANTEED TO RETURN TRUE
5
7HICH STATEMENTS ABOUT SESSION BEANS ARE TRUE #HOOSE ALL THAT APPLY
R! 4HE BEAN PROVIDER MUST WRITE THE METHOD PUBLIC VOID REMOVE IN BOTH STATELESS AND STATEFUL SESSION CLASSES
R" ,OCAL CLIENTS CAN REMOVE SESSION BEANS BY CALLING A METHOD ON THE BEANS HOME
R# 4HE REMOVE METHOD IN THE COMPONENT INTERFACE CAN BE USED ONLY BY REMOTE CLIENTS
R$ 4O ASK THE %*"(OME TO REMOVE A SESSION BEAN THE CLIENT MUST PROVIDE THE BEANS HANDLE
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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FRIIHHFUDPPRFNH[DP
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is
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3
'IVEN A REMOTE CLIENT @2 THAT HAS VALID REFERENCES TO SESSION BEANS @! AND @" AND GIVEN THAT ! IS A LOCAL CLIENT TO " WHICH STATEMENTS ARE TRUE #HOOSE ALL THAT APPLY
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local remote client a You canÕt giAveseaes B through a local reference, reference
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 61
WKHFOLHQWYLHZ
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7HEN COMPARING TWO SESSION OBJECTS WHAT IS TRUE #HOOSE ALL THAT APPLY
(spec: 65-66)
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R" 5SING THE IS)DENTICAL METHOD STATEFUL SESSION BEANS FROM THE SAME HOME WILL ALWAYS RETURN TRUE
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of R$ 5SING THE EQUALS METHOD STATELESS SESSION BEANS FROM THE SAME HOME The behavior iÞed
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Chapter 3. Exposing Yourself Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
Table of Contents Chapter 4. Being a Session Bean.................................................................. 1 Section 4.1. OBJECTIVES: Session Beans...................................................................................................................................... 2 Section 4.2. Exploring the session bean lifecycle........................................................................................................................... 4 Section 4.3. You remember how it all works, right ? Getting and using a stateful session bean.................................................. 6 Section 4.4. Stateful Session Bean, CREATION............................................................................................................................. 7 Section 4.5. There's obviously more to the bean's lifecycle than just creation and business methods......................................... 8 Section 4.6. Container Callbacks, for the special moments in a bean's life................................................................................... 9 Section 4.7. Container Callbacks come from TWO places:.......................................................................................................... 10 Section 4.8. Implementing the container callbacks...................................................................................................................... 11 Section 4.9. There are no Dumb Questions.................................................................................................................................. 14 Section 4.10. Sharpen your pencil................................................................................................................................................. 14 Section 4.11. Sharpen your pencil.................................................................................................................................................. 15 Section 4.12. Bean creation: when an object becomes a bean...................................................................................................... 16 Section 4.13. Bean things you can do during creation: stateful session bean)............................................................................ 24 Section 4.14. Bean Use: what happens AFTER creation.............................................................................................................. 26 Section 4.15. Bean things you can do within business methods:................................................................................................. 27 Section 4.16. Passivation: a stateful bean's chance at scalability................................................................................................. 28 Section 4.17. There are no Dumb Questions................................................................................................................................ 30 Section 4.18. Your job for passivation: make your state passivatable!........................................................................................ 31 Section 4.19. There are no Dumb Questions................................................................................................................................ 33 Section 4.20. Sharpen your pencil................................................................................................................................................ 33 Section 4.21. Bean things you can do in ejbActivate and ejbPassivate()..................................................................................... 35 Section 4.22. Bean Removal: when beans die.............................................................................................................................. 36 Section 4.23. Complaints about bean removal............................................................................................................................. 41 Section 4.24. Bean things you can do in ejbRemove()................................................................................................................. 44 Section 4.25. Implementing the AdviceBean as a stateFUL bean............................................................................................... 45 Section 4.26. BRAIN POWER....................................................................................................................................................... 45 Section 4.27. Things you can add if the bean is stateFUL............................................................................................................ 45 Section 4.28. There are no Dumb Questions................................................................................................................................ 45 Section 4.29. AdviceStatefulBean code........................................................................................................................................ 46 Section 4.30. AdviceStatefulBean CLIENT code.......................................................................................................................... 47 Section 4.31. Sharpen your pencil................................................................................................................................................ 48 Section 4.32. Deploying a stateful bean....................................................................................................................................... 49 Section 4.33. Compared to stateful beans, stateless beans have a simple life............................................................................. 50 Section 4.34. Bean things you can do from stateless bean methods............................................................................................ 56 Section 4.35. Writing a Session Bean:your job as Bean Provider................................................................................................ 58 Section 4.36. Sharpen your pencil................................................................................................................................................ 59 Section 4.37. Sharpen your pencil: Who does What?................................................................................................................... 67 Section 4.38. SessionContext : You need it more than it needs you............................................................................................ 68 Section 4.39. Overheard at THE TiKiBEAN LoUNGE................................................................................................................. 70 Section 4.40. What's allowed?....................................................................................................................................................... 71 Section 4.41. COFFEE CRAM: Mock Exam.................................................................................................................................. 72 Section 4.42. COFFEE CRAM: Mock Exam Answers................................................................................................................... 79
Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 1
session bean lifecycle
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 11
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean
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A:
4HE !0) DOESNT HAVE ADAPTER CLASSES FOR 3ESSION"EAN IMPLEMENTATIONS IE A CLASS THAT IMPLEMENTS ALL OF THE METHODS "UT THERES NO REASON YOU CANT MAKE ONE YOURSELF +EEP IN MIND THOUGH THAT WITH REAL WORLD BEANS YOU PROBABLY WILL HAVE CODE IN ONE OR MORE OF THE METHODS !ND YOU MIGHT EVEN BE WORKING WITH A BEAN AWARE )$% THAT PUTS THE METHODS IN FOR YOU ANYWAY 3TILL IT MIGHT BE HANDY TO MAKE YOURSELF A GENERIC BEAN THAT YOU TYPICALLY EXTEND FROM THAT HAS ALL OF THE METHODS FROM 3ESSION"EAN 7ITH STATELESS BEANS ESPECIALLY YOU HAVE TO IMPLEMENT EJB!CTIVATE AND EJB0ASSIVATE EVEN THOUGH THEYLL NEVER BE CALLED 3TATELESS BEANS ARE NEVER PASSIVATED YOULL SEE MORE ON THAT LATER IN THE CHAPTER
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) JUST REMEMBERED THAT ) READ SOMEWHERE THAT ENTERPRISE BEANS DONT SUPPORT INHERITANCE 7HATS THAT ABOUT
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!H A COMMON MISCONCEPTION 7ELL SORT OF %*" SUPPORTS REGULAR *AVA CLASS INHERITANCE BUT HAS NO CONCEPT OF BEAN INHERITANCE !ND NOW YOURE ASKING h7HAT THE HECK IS THE DIFFERENCE v 9OU ALREADY KNOW WHAT CLASS INHERITANCE IS ITS THE THING YOU DO IN *AVA WHEN ONE CLASS EXTENDS ANOTHER !ND YOU CAN DO THAT WITH A BEAN JUST LIKE ANY OTHER CLASS "UT BEAN INHERITANCE IF IT WERE SUPPORTED WOULD MEAN THAT A BEAN CLASS COULD EXTEND ANOTHER BEAN CLASS AND INHERIT NOT JUST THE CLASS INHERITABLE MEMBERS BUT ALSO ITS BEANNESS 7HAT KIND OF BEANNESS MIGHT BE INHERITABLE *UST IN CASE THEY DO DECIDE TO SUPPORT THIS IN THE FUTURE WHICH IS A POSSIBILITY 2EGULAR OLD NON ENTERPRISE BEANS DO SUPPORT BEAN INHERITANCE /NE IDEA MIGHT BE TO HAVE YOUR BEAN SUBCLASS INHERIT SOME OF THE DEPLOYMENT DESCRIPTOR SETTINGS OF ITS SUPERCLASS AND THEN OVERRIDE THE ONES IT WANTS TO CHANGE WITH A MUCH SMALLER INCOMPLETE DEPLOYMENT DESCRIPTOR 4HAT MIGHT BE COOL WERE NOT SURE "UT RIGHT NOW ITS JUST OUR LITTLE FANTASY )N THE MEANTIME GO AHEAD AND LET YOUR BEAN EXTEND ANOTHER CLASS IF IT MAKES SENSE FOR YOUR // DESIGN
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! BEAN MOVES FROM DOES NOT EXIST TO METHOD READY STILL FEELS CREEPY DOESNT IT HAVE TO EXIST BEFORE IT CAN MOVE BEGINNING WITH A CONSTRUCTOR "UT THE CONSTRUCTOR MAKES AN OBJECT NOT A BEAN 4O BE A BEAN THE OBJECT NEEDS TO BE GRANTED BEANNESS 7HEN AN OBJECT BECOMES A BEAN IT GETS ALL THE UNIQUE PRIVILEGES THAT COME WITH BEANNESS LIKE THE ABILITY TO GET SECURITY INFO ABOUT THE CLIENT OR LOOK UP SPECIAL DEPLOY TIME PROPERTIES IN THE BEANS SPECIAL SPACE IN *.$) OR GET A *$"# #ONNECTION FROM A POOL MANAGED BY THE CONTAINER
7HY DO YOU CARE ABOUT CREATION DETAILS "ECAUSE SOMEWHERE BETWEEN THE CONSTRUCTOR AND THE CREATE METHOD THE BEAN IS IN A 3CHROEDINGERS BEAN STATE 9OU MIGHT HAVE BEAN INITIALIZATION CODE LIKE GETTING A *$"# #ONNECTION OR LOOKING UP A REFERENCE TO ANOTHER BEAN THAT WILL FAIL IF YOU RUN IT TOO EARLY IN THE BEANS LIFE 7RITING GOOD BEAN CODE MEANS YOU MUST KNOW THE POINT AT WHICH AN OBJECT BECOMES A CARD CARRYING BEAN AND WHAT THAT MEANS TO YOU AS THE DEVELOPER
*WeÕre not explaining the whole Schroedinger reference here, except to say that it involves cats (animal-lovers be warned) and subatomic physics. For more info, look for Head First Quantum Physics in the future. WeÕre serious. Serious for us, anyway.
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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&OR EXAMPLE IF YOURE A STATEFUL SESSION BEAN YOUR CREATION IS A DIRECT RESULT OF THE CLIENT CALLING CREATE ON YOUR HOME )F YOURE A STATEFUL BEAN AND YOURE IN YOUR EJB#REATE METHOD THERE CAN BE ONLY ONE REASON A CLIENT HAS ASKED FOR YOU TO BE CREATED !ND THAT MEANS YOU CAN l ND OUT WHO THE CLIENT IS BY ASKING YOUR %*"#ONTEXT LIKE 3ESSION#ONTEXT FOR CLIENT SECURITY INFORMATION "UT IF YOURE A STATELESS BEAN YOUR CREATION ISNT TIED TO ANY PARTICULAR CLIENTS REQUEST YOULL LEARN ALL ABOUT THIS IN A FEW MORE PAGES )N FACT IF THE #ONTAINER WANTS TO IT CAN CREATE A BUNCH OF STATELESS BEANS FOR THE POOL BEFORE THERE ARE ANY CLIENTS !ND THAT MEANS A STATELESS BEAN CANNOT GET SECURITY INFORMATION ABOUT THE CLIENT DURING EJB#REATE "ECAUSE THERES NO CLIENT 4HERES ONLY THE #ONTAINER INVOKING A CONTAINER CALLBACK THATS NOT PART OF A CLIENT CALL AND WE DONT CONSIDER THE #ONTAINER TO BE A CLIENT 4HE #ONTAINER IS THE BOSS NOT THE CLIENT !ND THERE ARE SOME "EAN 4HINGS THAT CAN BE DONE ONLY WHILE THE BEAN IS IN WHAT THE #ONTAINER CONSIDERS hA MEANINGFUL TRANSACTION CONTEXTv 9OU CANT FOR EXAMPLE ACCESS A DATABASE FROM A METHOD THAT MIGHT NOT HAVE A TRANSACTION 3OME "EAN 4HINGS ARE MUTUALLY EXCLUSIVE )F YOURE USING CONTAINER MANAGED TRANSACTIONS #-4 #HAPTER YOU MUST NOT ASK YOUR %*"#ONTEXT TO GIVE YOU YOUR OWN TRANSACTION OBJECT /N THE OTHER HAND IF YOURE USING BEAN MANAGED TRANSACTIONS "-4 YOU CAN ASK FOR A TRANSACTION OBJECT BUT THEN YOU MUST NOT ASK YOUR CONTEXT TO ROLLBACK YOUR TRANSACTION 9OULL HAVE TO ROLLBACK THE TRANSACTION YOURSELF USING THE TRANSACTION OBJECT YOU GOT FROM YOUR CONTEXT
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean
Page 25
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Chapter 4. Being a Session Bean
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Page 26
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
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Page 27
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Chapter 4. Being a Session Bean
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7HEN THE #ONTAINER DECIDES A STATEFUL BEAN IS WASTING RESOURCES ITLL CALL THE BEANS EJB0ASSIVATE METHOD AND THEN SAVE THE BEAN INTO TEMPORARY STORAGE
7HY DO YOU CARE ABOUT PASSIVATION DETAILS "ECAUSE THE #ONTAINER USES A SPECIAL SET OF RULES NEARLY IDENTICAL TO 3ERIALIZATION TO PASSIVATE YOUR BEAN AND ITS YOUR JOB TO MAKE SURE YOUR INSTANCE VARIABLES ARE IN A STATE THAT WORKS FOR PASSIVATION !ND ITS JUST A TINY BIT MORE SUBTLE THAN SIMPLY MAKING NON 3ERIALIZABLE VALUES TRANSIENT
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
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Page 30
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(OW DOES THE #ONTAINER KNOW WHEN TO PASSIVATE A BEAN
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Q:
'EE CAN YOU BE ANY MORE NON COMMITTAL (OW LONG IS hSOME PERIOD OF TIMEv AND WHAT DETERMINES WHETHER THE #ONTAINER @NEEDS TO PASSIVATE THE BEAN
A:
4HERE IS NOTHING IN THE SPEC THAT SAYS YOURE ALLOWED TO TUNE THE PARAMETERS FOR THE #ONTAINERS PASSIVATION DECISIONS "UT MANY CONTAINERS DO GIVE YOU A WAY TO SET A VARIETY OF VALUES 4HE DECISION MIGHT BE BASED ON AVAILABILITY OF RE SOURCES LIKE hPASSIVATE STATEFUL SES SION BEANS ONLY WHEN AVAILABLE 2!- HITS THIS LEVELv OR hPASSIVATE BEANS ONLY WHEN THE NUMBER OF ACTIVE STATEFUL SESSION BEANS REACHESv !ND YOU MIGHT BE ABLE TO SET THE INACTIVITY VALUE FOR THE AMOUNT OF ELAPSED TIME AT WHICH THE #ONTAINER SHOULD PASSIVATE
Q:
7HAT IF THE CLIENT CRASHES #AN THE SERVER TELL )S THERE ANY KIND OF DISTRIBUTED GARBAGE COL LECTION OR LEASING LIKE THERE IS WITH 2-) /R IS THE SERVER REALLY JUST BASING EVERYTHING ON INACTIVITY
A:
!CCORDING TO THE SPEC THERE IS NO GUARANTEE OF DISTRIBUTED GAR BAGE COLLECTION WHICH MEANS YOU SHOULD ASSUME THAT IT ISNT HAPPEN ING 0ART OF THE REASON IS BECAUSE AN %*" CLIENT COULD AT LEAST IN THEORY BE A #/2"! CLIENT RATHER THAN A *AVA 2-) CLIENT 3O THE WHOLE CONCEPT OF 2-)S DISTRIBUTED GARBAGE COLLECTION WOULDNT APPLY !ND JUST A QUICK OFF PATH HERE DISTRIBUTED GARBAGE COLLECTION DGC OR DISTRIBUTED LEASING ARE WAYS IN WHICH A SERVER CAN FIGURE OUT IF A CLIENT HAS WITH DGC NULLED OUT THEIR REFERENCE TO THE STUB OR WITH LEASING IF THE CLIENT HAS SIMPLY GONE AWAY EITHER BY SHUTTING DOWN THE APP CRASHING OR DISCONNECTING FROM THE NETWORK 4HE BOTTOM LINE IS THAT YOU HAVE TO ASSUME THAT THE %*" SERVER DOESNT SUPPORT THIS SO YOURE STUCK WITH INACTIVITY AND PERHAPS SOME KIND OF ,25 ,EAST 2ECENTLY 5SED ALGO RITHMS FOR SELECTING WHO SHOULD BE PASSIVATED IF RESOURCES BECOME SCARCE AND THE #ONTAINER NEEDS TO BRING DOWN SOME BEANS
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
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Page 32
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 4. Being a Session Bean
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Page 33
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#ANT YOU JUST MARK YOUR NON 3ERIALIZABLE VARIABLES TRANSIENT )SNT THAT WHAT TRANSIENT IS FOR
A:
9OU COULD YES BECAUSE THE #ONTAINER IS REQUIRED TO FOLLOW THE RULES FOR 3ERIALIZATION WHEN IT PASSIVATES A BEAN EVEN IF THE #ONTAINER CHOOSES TO USE SOMETHING OTHER THAN SERIALIZATION TO GET THE JOB DONE "UT THERES A LITTLE TEENY COMMENT IN THE SPEC WHICH SAYS THAT THERES AN EXCEPTION TO THE RULE THAT PASSIVATION BEHAVE JUST LIKE SERIALIZATION 4HE EXCEPTION IS THAT WHILE SERIALIZATION IS REQUIRED TO BRING BACK TRANSIENT FIELDS WITH DEFAULT VALUES PASSIVATION DOESNT GUARANTEE THAT 7HAT DOES THIS MEAN 4HINK ABOUT IT )T MEANS YOU CANT RELY ON TRANSIENT TO GIVE YOU BACK YOUR DEFAULTS SO AFTER ACTIVATION YOU COULD END UP WITH WELL ANYTHING IN A VARIABLE THATS MARKED TRANSIENT 3O YOU ARE FREE TO USE TRANSIENT AND IT CAN MAKE PASSIVATION MORE EFFICIENT BUT THE IMPLICATION ISRESET YOUR TRANSIENT VARIABLES YOURSELF IN EJB!CTIVATE
Q:
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9OU CAN CERTAINLY PUT CODE IN EJB!CTIVATE OR EJB0ASSIVATE REGARDLESS OF WHETHER THE BEAN IS STATELESS OR STATEFUL EVEN THOUGH IT WILL NEVER BE CALLED IF THE BEAN IS STATELESS 4HINK ABOUT IT ,OOK AT THE 3ESSION"EAN INTERFACE .OTICE THAT THERE ISNT A SEPARATE 3TATEFUL3ESSION"EAN INTERFACE AND 3TATELESS3ESSION"EAN INTERFACE 4HERES JUST 3ESSION "EAN AND BOTH STATELESS AND STATEFUL BEANS IMPLEMENT IT 3O THERES NOTHING IN YOUR CLASS THAT SPECIFICALLY SAYS YOUR BEAN IS STATELESS )TS ONLY AT DEPLOY TIME WHEN YOU TELL THE DEPLOYMENT DESCRIPTOR THAT THE BEAN IS STATELESS OR STATEFUL THAT IT ACTUALLY MATTERS )N FACT YOU COULD WRITE A BEAN THAT HAS ONLY A NO ARG CRE ATE AND KEEPS NO CLIENT STATE AND YOU CAN DEPLOY IT WITH EITHER SETTINGSTATELESS OR STATEFULAND IT WILL WORK AS LONG AS YOUVE TAKEN CARE OF PASSIVATION AND ACTIVATION
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean
Page 62
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Chapter 4. Being a Session Bean
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HAT IS TRUE ABOUT A SESSION BEANS LIFECYCLE #HOOSE ALL THAT APPLY
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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.OTE 4HE REAL EXAM HAS SEVERAL TYPES OF @DRAG AND DROP QUESTIONS THAT WERE GOING TO DO A LAME JOB OF SIMULATING WITH THIS QUESTION -ATCH THE METHODS ON THE LEFT WITH THE INTERFACES IN WHICH THOSE METHODS CAN BE FOUND ON THE RIGHT ! MATCH IS CORRECT IF THE METHOD IS EITHER DECLARED IN OR INHERITED BY THE INTERFACE .OTE 4HERE MAY BE SOME MANY TO ONE AND ONE TO MANY RELATIONSHIPS IN YOUR ANSWER ! AFTER#OMPLETION
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)N WHAT CASES WILL THE CONTAINER FAIL TO CALL EJB2EMOVE ON A SESSION BEAN #HOOSE ALL THAT APPLY
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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&OR THIS DRAG AND DROP TYPE QUESTION YOU CAN USE EACH ELEMENT ONLY ONCE 7HICH INTERFACE SHOULD BE MATCHED WITH WHICH FACT SO THAT ALL FOUR MATCHES ARE CORRECT REMOTE COMPONENT A (AS A JHW+RPH+DQGOH METHOD
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HICH STATEMENTS ARE TRUE FOR STATELESS SESSION BEAN INSTANCES #HOOSE ALL THAT APPLY
R! !NY INSTANCE CAN BE USED FOR ANY CLIENT R" #ONVERSATIONAL STATE MUST BE RETAINED ACROSS METHODS R# #ONVERSATIONAL STATE MUST BE RETAINED ACROSS TRANSACTIONS R$ 4HEY CAN BE PASSIVATED R% 4HEY DO NOT SUPPORT TRANSACTIONS
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Page 79
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(spec: 71)
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 80
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7HICH ARE VALID REMOTE COMPONENT INTERFACES FOR A SESSION BEAN #HOOSE ALL THAT APPLY
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 81
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7HAT IS TRUE ABOUT A SESSION BEANS LIFECYCLE #HOOSE ALL THAT APPLY
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R% 4HE PROVIDER MUST ASSUME THAT ANY REFERENCE TO THE 3ESSION#ONTEXT OBJECT WILL BE NOT SURVIVE PASSIVATION IF THE 3ESSION#ONTEXT OBJECT IS NOT SERIALIZABLE no matter what!
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'IVEN A STATELESS SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCATION FROM WHICH METHODS CAN YOU ACCESS ANOTHER BEAN #HOOSE ALL THAT APPLY
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 82
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.OTE 4HE REAL EXAM HAS SEVERAL TYPES OF @DRAG AND DROP QUESTIONS THAT WERE GOING TO DO A LAME JOB OF SIMULATING WITH THIS QUESTION -ATCH THE METHODS ON THE LEFT WITH THE INTERFACES IN WHICH THOSE METHODS CAN BE FOUND ON THE RIGHT ! MATCH IS CORRECT IF THE METHOD IS EITHER DECLARED IN OR INHERITED BY THE INTERFACE .OTE 4HERE MAY BE SOME MANY TO ONE AND ONE TO MANY RELATIONSHIPS IN YOUR ANSWER 1
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7HAT IS TRUE ABOUT A SESSION BEANS LIFECYCLE #HOOSE ALL THAT APPLY
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7HICH OF THE FOLLOWING METHODS ARE CONTAINER CALLBACK METHODS #HOOSE ALL THAT APPLY
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 83
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)N WHAT CASES WILL THE CONTAINER FAIL TO CALL EJB2EMOVE ON A SESSION BEAN #HOOSE ALL THAT APPLY
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7HICH METHODS ALLOW BOTH STATEFUL AND STATELESS SESSION BEANS WITH BEAN MANAGED TRANSACTION DEMARCATION TO ACCESS 5SER4RANSACTION METHODS #HOOSE ALL THAT APPLY
(spec: 80, 90)
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16
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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PRFNH[DPDQVZHUV
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(spec: 75)
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HICH STATEMENTS ARE TRUE FOR STATELESS SESSION BEAN INSTANCES #HOOSE ALL THAT APPLY
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Chapter 4. Being a Session Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 5. Entities Are Persistent
Table of Contents Chapter 5. Entities Are Persistent................................................................ 1 Section 5.1. OBJECTIVES: Entity Beans........................................................................................................................................ 2 Section 5.2. What's an entity bean?................................................................................................................................................ 3 Section 5.3. Entities vs. Entity Beans............................................................................................................................................. 4 Section 5.4. There are no Dumb Questions.................................................................................................................................... 5 Section 5.5. There are no Dumb Questions.................................................................................................................................... 6 Section 5.6. Entity beans from the client's point of view............................................................................................................... 7 Section 5.7. Entity bean overview................................................................................................................................................... 8 Section 5.8. Entity bean overview................................................................................................................................................... 9 Section 5.9. A very simple Customer entity bean......................................................................................................................... 10 Section 5.10. An entity bean's client view...................................................................................................................................... 11 Section 5.11. Entity bean Remote component interface............................................................................................................... 12 Section 5.12. Entity bean Remote component interface............................................................................................................... 13 Section 5.13. Rules for the Remote component interface............................................................................................................. 14 Section 5.14. Entity bean Remote home interface........................................................................................................................ 15 Section 5.15. What does the client really want from an entity bean home?................................................................................. 16 Section 5.16. Entity bean Remote component interface............................................................................................................... 17 Section 5.17. When finders have a dark side................................................................................................................................. 18 Section 5.18. There are no Dumb Questions................................................................................................................................. 19 Section 5.19. Home business methods to the rescue................................................................................................................... 20 Section 5.20. Rules for the Remote home interface..................................................................................................................... 21 Section 5.21. Sharpen your pencil................................................................................................................................................. 22 Section 5.22. Session bean create() vs. entity bean create()........................................................................................................ 23 Section 5.23. Session bean remove() vs. entity bean remove().................................................................................................... 24 Section 5.24. Entity/bean/instance death.................................................................................................................................... 27 Section 5.25. Client calls remove()............................................................................................................................................... 28 Section 5.26. Entity bean client view............................................................................................................................................ 29 Section 5.27. COFFEE CRAM....................................................................................................................................................... 30 Section 5.28. COFFEE CRAM....................................................................................................................................................... 33
Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 1
entity bean intro
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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!S A CLIENT YOULL PROBABLY SPEND A LOT MORE TIME USING REFERENCES TO EXISTING CUSTOMERS THAN YOULL SPEND CREATING NEW CUSTOMERS 7HETHER YOURE UPDATING A SPECIl C CUSTOMER OR DOING A BATCH OPERATION ON MANY CUSTOMERS YOULL NEED HOME INTERFACE CODE THAT LETS YOU SELECT CUSTOMERS MORE THAN YOULL NEED CREATION METHODS )N FACT THE CREATE METHOD IS OPTIONAL FOR ENTITY BEANS "ECAUSE YOU MIGHT HAVE A POLICY THAT SAYS NEW ENTRIES IN THE DATABASE MUST BE DONE DIRECTLY THROUGH A DATABASE ADMIN TOOL FOR EXAMPLE "UT YOURE REQUIRED TO PUT AT LEAST ONE l NDER METHOD FOR AN ENTITY BEAN HOMEYOU CAN HAVE AS MANY l NDERS AS YOU LIKE BUT YOU MUST HAVE l ND"Y0RIMARY+EY3TRING PRIMARY+EY IN EVERY ENTITY HOME 7HICH MEANS IT MIGHT BE THE ONLY METHOD DECLARED IN THE HOME INTERFACE
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent
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Chapter 5. Entities Are Persistent
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Page 27
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-V\Q\aJMIVQV[\IVKMLMI\P 3O WE ALL KNOW THAT AN ENTITY BEAN IS A REPRESENTATION OF SOME REAL ENTITY IN AN UNDERLYING PERSISTENT STORE USUALLY AS A ROW IN A DATABASE BLAH BLAH BLAH "UT THERES STILL SOME CONFUSION ABOUT WHAT DISTINGUISHES AN ENTITY FROM AN ENTITY BEAN FROM AN ENTITY BEAN INSTANCE
%NTITY 4HE REAL THING IN THE UNDERLYING PERSISTENT STORE 4HE ROW IN THE DATABASE ALTHOUGH IT CAN BE MORE COMPLEX !N ENTITY DIES WHEN ITS ROW IS DELETED FROM THE UNDERLYING STORE EITHER THROUGH A DIRECT DATABASE DELETE LIKE SOMEONE USING A DATABASE ADMIN TOOL OR BECAUSE SOMEONE CALLS REMOVE ON THE BEANS HOME OR COMPONENT INTERFACE
%NTITY BEAN 4HE COMPONENT THAT REPRESENTS THE UNDERLYING REAL ENTITY "UT THIS ONES TRICKY IS IT THE CLASS )S IT THE INTERFACE )S IT THE INSTANCE OF THE BEAN CLASS $URING DEVELOPMENT AND DEPLOYMENT THE ENTITY BEAN IS THE WHOLE COMPONENT THE TWO INTERFACES $$ AND BEAN CLASS "UT AT RUNTIME IT CAN GET A LITTLE FUZZY 3 OMETIMES WE USE hENTITY BEANv TO DESCRIBE THE POSSIBILITY OF REPRESENTING A PARTICULAR ENTITY AS A BEAN )N OTHER WORDS IF THERES AN ENTITY FOR "O 2ODGERS IN THE DATABASE THEN WE CAN SAY THAT THERE IS A "O 2ODGERS ENTITY BEAN EVEN IF THERES NO BEAN INSTANCE CURRENTLY REPRESENTING THAT ENTITY )F AN ENTITY EXISTS FOR A PARTICULAR BEAN TYPE LIKE #USTOMER &RED &OO THE ENTITY BEAN FOR THAT ENTITY IS SAID TO EXIST !N ENTITY BEAN IS SAID TO DIE WHEN ITS UNDERLYING ENTITY IS DELETED AS IN h4HERES NO &RED &OO ENTITY BEANv "UT THAT DOESNT MEAN THE INSTANCE ON THE HEAP DIES
%NTITY BEAN INSTANCE 4HE INSTANCE OF THE BEAN CLASS ON THE HEAP "EAN DEATH IS INTIMATELY TIED TO THE DATABASE BUT BEAN INSTANCE DEATH AS IN hYOURE HEADIN FOR GARBAGE COLLECTION PALv IS TIED TO THE WHIMS OF THE #ONTAINER OR A SERVER CRASH 9ES IT REALLY IS THAT CONFUSING 9OU HAVE TO KNOW THE CONTEXT TO KNOW HOW THE WORD @BEAN IS BEING USED )F IT MEANS THE BEAN REPRESENTING THE ENTITY THEN THAT BEAN WILL DIE WHEN THE ENTITY DIES AND THE %*" OBJECT FOR THAT ENTITY GOES AWAY "UTAND HERES WHERE IT GETS WEIRDTHE ENTITY BEAN INSTANCE DOESNT DIE IT JUST GOES BACK TO THE POOL 4HINK OF THE PHRASE hENTITY BEANv AS MORE CONCEPTUAL THAN PHYSICAL )N MOST CASES WE WONT HAVE TO DISTINGUISH BETWEEN THE BEAN AND ITS INSTANCE OR THE DISTINCTION WILL BE SO OBVIOUS THAT ITS NOT AN ISSUE
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 30
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 5. Entities Are Persistent
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Page 31
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 5. Entities Are Persistent
Page 32
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 33
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 34
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Chapter 5. Entities Are Persistent
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Chapter 5. Entities Are Persistent Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 6. Being an Entity Bean
Table of Contents Chapter 6. Being an Entity Bean.................................................................. 1 Section 6.1. OBJECTIVES............................................................................................................................................................... 2 Section 6.2. The real power of entity beans is synchronization..................................................................................................... 4 Section 6.3. Oh no!: The entity bean and the entity it represents have different data!................................................................. 5 Section 6.4. How the entity bean and the underlying entity stay synchronized............................................................................ 7 Section 6.5. The only question is WHO does the work when it's time to synchronize.................................................................. 8 Section 6.6. Container-managed vs. bean-managed persistence.................................................................................................. 9 Section 6.7. there are no Dumb Questions................................................................................................................................... 10 Section 6.8. Off the path: A brief history on the evolution of CMP 2.0........................................................................................ 11 Section 6.9. The EntityBean interface adds three new container callbacks (including two just for synchronization)............... 16 Section 6.10. Even the methods that are the same, don't behave the same................................................................................. 17 Section 6.11. But wait... there's more! Entity beans have new home container callbacks , too................................................... 18 Section 6.12. Writing a CMP entity bean: make it abstract ......................................................................................................... 19 Section 6.13. You put three kinds of things in your bean class:................................................................................................... 20 Section 6.14. PLUS... (ok, that's four things...)............................................................................................................................. 21 Section 6.15. Virtual fields are NOT instance variables!.............................................................................................................. 22 Section 6.16. Sharpen your penil.................................................................................................................................................. 23 Section 6.17. Complete code for the CustomerBeanCMP class.................................................................................................... 24 Section 6.18. Sharpen your pencil................................................................................................................................................ 25 Section 6.19. Entity bean instance lifecycle.................................................................................................................................. 26 Section 6.20. Entity bean instance transitions............................................................................................................................. 27 Section 6.21. there are no Dumb Questions................................................................................................................................. 28 Section 6.22. Sharpen your pencil................................................................................................................................................ 29 Section 6.23. Sharpen your pencil................................................................................................................................................ 30 Section 6.24. So how DID the client get a reference to the EJB object for #28?......................................................................... 31 Section 6.25. Bean things you can do during entity construction:.............................................................................................. 33 Section 6.26. CMP Entity bean creation....................................................................................................................................... 34 Section 6.27. Creating a new entity bean: CMP entity bean........................................................................................................ 35 Section 6.28. CMP Entity bean creation....................................................................................................................................... 36 Section 6.29. Implement your ejbCreate() methods.................................................................................................................... 37 Section 6.30. Object identity: the primary key............................................................................................................................. 38 Section 6.31. Implement your ejbPostCreate() methods............................................................................................................. 40 Section 6.32. BRAIN POWER....................................................................................................................................................... 41 Section 6.33. Bean things you can do during entity creation:..................................................................................................... 44 Section 6.34. CMP Entity finder................................................................................................................................................... 45 Section 6.35. Finding an existing entity....................................................................................................................................... 46 Section 6.36. CMP Entity bean finders......................................................................................................................................... 47 Section 6.37. YOU don't implement the Finder methods!........................................................................................................... 48 Section 6.38. CMP Home Business Methods................................................................................................................................ 51 Section 6.39. Client invokes a Home Business Method............................................................................................................... 52 Section 6.40. Bean things you can do in home business methods............................................................................................... 53 Section 6.41. Starting a business method (in a transaction)........................................................................................................ 54 Section 6.42. Completing a business method (and a transaction)............................................................................................... 55 Section 6.43. Being John Entity Bean.......................................................................................................................................... 56 Section 6.44. Activation/passivation of a CMP entity bean......................................................................................................... 58 Section 6.45. Sharpen your pencil................................................................................................................................................ 59 Section 6.46. Bean things you can do during activation and loading.......................................................................................... 60 Section 6.47. Bean things you can do during passivation and storing......................................................................................... 61 Section 6.48. Commit options: what REALLY happens to a bean after a transaction commits?............................................... 62 Section 6.49. There are no Dumb Questions................................................................................................................................ 63 Section 6.50. Exercise: CMP entity bean Creation....................................................................................................................... 65 Section 6.51. Exercise: Entity Bean Business Method (with activation & passivation).............................................................. 66 Section 6.52. Exercise................................................................................................................................................................... 67 Section 6.53. COFFEE CRAM....................................................................................................................................................... 68 Section 6.54. COFFEE CRAM....................................................................................................................................................... 73
Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean
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2ELAX 2EALLY 7ITH "-0 YOU STILL GET YOUR DATABASE CONNECTION FROM THE #ONTAINER BY LOOKING UP AS YOU SAID A RESOURCE FACTORY REFERENCE JAVAXSQL$ATA3OURCE 'EE YOU MUST HAVE BEEN READING AHEAD TO THE CHAPTER ON THE %*" ENVIRONMENT "ECAUSE YOURE RIGHT YOU NEED TO GET A CONNECTION FROM A CONNECTION POOL MANAGED BY THE #ONTAINER "UT ONCE YOU GET THE CONNEC TION FOR A "-0 BEAN YOURE ON YOUR OWN FOR SENDING IT STATEMENTS TO DO ).3%24 $%,%4% 50$!4% 3%,%#4 OPERATIONS !ND WHILE WERE HERE REMEMBER THAT DA TABASE ACCESS IS NOT JUST FOR ENTITY BEANS !.9 BEAN CAN GO TO THE DATABASE AS PART OF ITS BUSINESS LOGIC 3ESSION BEANS AND MESSAGE DRIVEN BEANS MIGHT FIND PLENTY OF REASONS TO LOOK SOMETHING UP OR STORE SOMETHING IN A DATABASE 4HE DIFFERENCE BETWEEN ENTITY BEANS AND THE OTHER TWO BEAN TYPES IS THAT ENTITY BEANS EXIST ONLY BECAUSE THERES SOMETHING IN A DATA BASE 3OMETHING THE BEAN REPRESENTS 3O ENTITY BEANS ARE BY DEFINITION TIED TO SOMETHING IN A PERSISTENT STORE
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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&OR ANY ENTITY BEAN USING CONTAINER MANAGED PERSISTENCE #-0 YOU WILL ALWAYS HAVE AT LEAST SEVEN CONTAINER CALLBACKSALL FROM THE %NTITY"EAN INTERFACE IMPLEMENTATION 9OU DONT HAVE TO HAVE A CREATE METHOD IN YOUR HOME BUT IF YOU DO HAVE CREATE METHODS YOU MUST MATCH EACH CREATE WITH NOT ONE BUT TWO METHODS EJB#REATE AND EJB0OST#REATE )F YOU HAVE HOME BUSINESS METHODS YOU MUST WRITE A MATCHING EJB(OME METHOD.AME METHOD IN THE BEAN CLASS )F YOU USE BEAN MANAGED PERSISTENCE "-0 WHERE YOU WRITE YOUR OWN DATABASE ACCESS CODE YOU ALSO MUST MATCH EACH l NDER METHOD WITH AN EJB&IND WHATEVER METHOD 2EMEMBER THE ONLY METHOD REQUIRED IN A HOME INTERFACE IS l ND"Y0RIMARY+EY "UT IN A #-0 BEAN YOU WONT PUT ANY l NDERS IN YOUR BEAN CLASS EVEN THOUGH THEYRE IN YOUR HOME INTERFACE
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 22
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean
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PLACES IS BECAUSE IT DEPENDS ON WHICH INTERFACE THE CLIENT USES TO CALL THE METHOD THAT IN TURN CALLS A SELECT METHOD 3O IF A CLIENT CALLS A HOME BUSINESS METHOD AND THE HOME METHOD CALLS AN EJB3ELECT METHOD THE BEAN STAYS IN THE POOL TO RUN THE METHOD "UT IF THE SELECT METHOD IS CALLED FROM A METHOD IN THE BEANS COMPONENT INTERFACE THAT MEANS THE METHOD IS RUNNING ON A SPECIFIC ENTITY SAY &RANK &OOF SO THE BEAN IS IN THE METHOD READY STATE
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 6. Being an Entity Bean
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Page 63
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(OW DOES THESE COMMIT OPTIONS AFFECT ME $O ) NEED TO KNOW WHICH ONE MY #ONTAINER IS CHOOSING $O ) GET A CHOICE
CREATED THAT THEN STAYS STUCK TO THE %*" OBJECT !RENT POOLS MORE EFlCIENT BECAUSE YOU NEED ONLY ENOUGH BEANS TO SERVICE THE ACTUAL IN PROGRESS METHODS
A:
A:
!CCORDING TO THE SPECIFICATION YOUR VENDOR IS FREE TO USE ANY OF THE THREE OPTIONS 9OUR CONTAINER MIGHT LET YOU CHOOSE OR TUNE THE OPTION BUT DONT ALWAYS COUNT ON IT "UT DO YOU NEED TO KNOW WHICH IS BEING USED 9OU CAN SEE WHERE THE TRADE OFFS ARE OF COURSEIF YOU KEEP THE ENTITY LOCKED IN THE DATABASE NO OTHER APPLICATIONS CAN USE THAT ENTITYS DATA 4HATS FINE IF THE %*" IS THE ONLY APPLICATION THAT NEEDS THAT DATABASE !ND THAT OPTION COMMIT OPTION ! GIVES YOU THE BEST PERFORMANCE WHEN A BUSINESS METHOD CALL COMES IN FOR THE ENTITY BECAUSE THERES NO EJB!CTIVATE THE BEAN NEVER WENT BACK TO THE POOL AND MORE SIGNIFICANTLYTHERES NO TRIP TO THE DATABASE OR AN EJB,OAD
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&OR THIS REASON MOST VENDORS WONT USE OPTION ! AS A DEFAULT THEY ALLOW IT ONLY IF THE DEPLOYER OR ADMIN CHOOSES IT ASSUMING ITS EVEN SUPPORTED AT ALL
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) SEE ANOTHER POSSIBLY EVEN 7/23% PROBLEM WITH OPTION ! DOESNT THIS MEAN A CONTINUALLY GROWING HEAP FULL OF OBJECTS ,IKE EACH TIME SOMEONE USES A PARTICULAR ENTITY AN ENTITY BEAN INSTANCE IS
.O CONTAINER WORTH CONFIGURING WOULD LEAVE YOU STUCK WITH A CONSTANTLY ENDLESSLY GROWING ACCUMULATION OF OBJECTS %VEN A CONTAINER THAT DOES USE OPTION ! CAN USE SOMETHING LIKE A ,25 ,EAST 2ECENTLY 5SED ALGORITHM TO SAY TO ITSELF h(MMM NOBODY HAS CALLED A METHOD ON ENTITY FOR A LONG TIME SO )LL PASSIVATE THAT BEAN AND PUT HIM BACK IN THE POOL AND UNLOCK THE ROW v "UT WITH AT LEAST THE OPTION OF USING OPTION ! A CONTAINER CAN SAY TO ITSELF h4HIS ENTITY IS REALLY POPULAR )TS A BIG PAIN TO KEEP GOING TO THE DATABASE AND DOING THE WHOLE LOAD STOREACTIVATEPASSIVATE CYCLE EACH TIME SO )LL JUST KEEP HIM LOADED AND READY EVEN BETWEEN TRANSACTIONSv
Q:
/H MAN ) JUST THOUGHT OF SOMETHING 2%!,,9 BAD WITH THIS ARCHITECTUREEVEN IF YOU DO ./4 KEEP ACCUMULATING ENTITY BEANS WHAT ABOUT THE %*" OBJECTS $ONT THEY JUST KEEP GROWING AND GROWING SO THAT EACH TIME A CLIENT DOES A lND AND GETS BACK A STUB AN %*" OBJECT IS CREATED FOR THAT ENTITY AND IT JUST STAYS AROUND UNTIL THE ENTITY ITSELF IS REMOVED !T ANY GIVEN TIME ) WILL HAVE ALL THE %*" OBJECTS ON THE HEAP THAT REPRESENT EVERY ENTITY ANYONE HAS EVER ACCESSED UP TO THAT POINT
A:
!H NOW WE COME TO THE DIFFERENCE BETWEEN THE hCONCEPTUALv VIEW OF THE ARCHITECTURE AND THE hACTUALv IMPLEMENTATION !CCORDING TO THE SPEC YOURE
SUPPOSED TO ASSUME THAT THIS IS INDEED HOW IT WORKS WHEN A CLIENT WANTS AN ENTITY BEAN EITHER THROUGH A CREATE OR FIND THE #ONTAINER MAKES AN %*" OBJECT FOR THAT ENTITY hHERES THE %*" OBJECT FOR HERES THE %*" OBJECT FOR v ETC !ND AS A "EAN 0ROVIDER AS OPPOSED TO SAY A CONTAINERSERVER PROVIDER YOU ARE TO PROGRAM AS IF THATS REALLY THE WAY IT WORKS "UT INTERNALLY THE #ONTAINER MIGHT BE DOING SOMETHING QUITE DIFFERENT FROM THE CONCEPTUAL ARCHITECTURAL VIEW )MAGINE THAT 9/5 WERE A CONTAINER DEVELOPERHOW WOULD YOU IMPLEMENT THINGS /NE IDEA MIGHT BE TO PUT THE BURDEN ON THE CLIENTS BY KEEPING ALL THE INFORMATION IN THE STUBS &OR EXAMPLE WHEN THE CLIENT GETS A STUB TO AN %*" OBJECT YOU CAN MAKE SURE THAT THE STUB KNOWS THE UNIQUE )$ FOR THE ENTITY IE THE PRIMARY KEY "UT THE %*" OBJECTS MIGHT BE GENERIC IN SUCH A WAY THAT WHEN THE CLIENT CALLS A METHOD ON A STUB THAT STUB IS CONNECTED NOT TO AN %*" OBJECT JUST FOR THAT ENTITY BUT RATHER A ONE %*" OBJECT FITS ALL THAT KNOWS HOW TO MAKE SURE THE METHOD ENDS UP AT THE RIGHT ENTITY 4HAT WAY WHEN A CLIENT ISNT USING AN %*" OBJECT THAT %*" OBJECT ISNT SITTING AROUND WASTING SPACE 4HATS JUST ONE IDEA
Q:
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 64
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there are no
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7ELL WE CANT REALLY ANSWER THAT BUT IF WE WERE IN A BETTING MOOD OUR MONEY WOULD BE ON OPTION " ! @SMART OPTION " THAT KNOWS WHEN IT MAKES SENSE TO HANG ON TO A BEAN AND WHEN IT DOESNT "UT AVOIDING THE EJB!CTIVATE WHICH IS USUALLY USELESS ANYWAY IS A 'OOD 4HING
Q:
"UT ISNT THE HIT TO THE DATABASETHE LOADA MUCH BIGGER HIT THAN JUST ONE MORE METHOD CALL ON THE STACK
A:
&IRST OF ALL ACTIVATION IS PROBABLY A LITTLE MORE THAN JUST ONE MORE METHOD CALL ON THE STACK BECAUSE THERES OVERHEAD JUST IN MAINTAINING THE ORGANIZATION OF THE POOL ITSELF "UT YES YOURE RIGHT ABOUT THE DATABASE HIT BEING A BIGGER DEAL "UT THERES ALL SORTS OF WAYS THE #ONTAINER CAN OPTIMIZE AND WHATS THE ALTERNATIVE 4HE ONLY ALTERNATIVE OPTION ! KEEPS THE DATABASE LOCKED WHICH IS TYPICALLY NOT WHAT YOU WANT
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) THINK WE MENTIONED THIS EARLIERIF YOU KNOW ABSOLUTELY POSITIVELY NO QUESTION THAT YOUR %*" APP IS THE ONLY THING TOUCHING THAT DATABASE THEN YES IF YOUR VENDOR SUPPORTS IT YOULL HAVE BETTER PERFORMANCE WITH OPTION ! /F COURSE CACHING THINGS IN MEMORY IS
STILL DANGEROUS BECAUSE ENTITIES ARE PERSISTENT 3O THE VENDOR STILL MUST IMPLEMENT SOMETHING THAT SAVES THE STATE OF THE ENTITIES TO THE DATABASE IF THEY CHANGE 3O THERE WILL STILL BE STORING IF NOT LOADING 4HERE ARE STILL OTHER POTENTIAL PROB LEMS WITH OPTION ! THOUGH &OR EXAMPLE YOU MIGHT HAVE A SERVER THAT SUPPORTS CLUSTERING AND THE SERVER WILL HAVE TO BE CERTAIN THAT ALL INSTANCES OF THAT ENTITY BEAN IN SYNC NOT JUST WITH THE DATABASE BUT WITH ONE ANOTHER "UT THATS ANOTHER ISSUE 9OULL LEARN MORE IN THE PATTERNS AND PERFORMANCE CHAPTER
Q:
3O IS THE REAL POINT OF ALL THIS THE FACT THAT AS LONG AS YOURE IN A TRANSACTION YOU WONT HAVE ALL THESE LOADSTORE ACTIVATEPASSIVATE CALLS
A:
9ES A BIG PART OF THE POINT ANYWAY
Q:
YOURE DOING MORE LOADSSTORES THAN YOU NEED TO SO THE KEY IS TO HAVE YOUR TRANSACTIONS BE AS LONG AS YOU NEED AND NO LONGER
Q:
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 6. Being an Entity Bean
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Page 68
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R# 7HEN IMPLEMENTING A ONE TO MANY RELATIONSHIP THE JAVAUTIL,IST INTERFACE MUST NOT BE USED
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 6. Being an Entity Bean Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 7. When Beans Relate
Table of Contents Chapter 7. When Beans Relate.................................................................... 2 Section 7.1. OBJECTIVES: Entity Relationships: CMP and CMR................................................................................................. 3 Section 7.2. Beanifying your movie database................................................................................................................................. 4 Section 7.3. But we don't want to think in TABLES We want to think in CLASSES..................................................................... 5 Section 7.4. We need relationships between the Movie bean and the Director............................................................................. 7 Section 7.5. Why should the Director be a bean? Why can't it just be data?................................................................................. 8 Section 7.6. Relationships and multiplicity.................................................................................................................................... 9 Section 7.7. Multiplicity in Bean Classes...................................................................................................................................... 10 Section 7.8. Multiplicity affects return type !................................................................................................................................ 11 Section 7.9. You need a pair of abstract getters and setters for each CMP field (column values) and each CMR field (relationship with another entity)....................................................................................................................................................................... 12 Section 7.10. Defining your "abstract persistence schema" (virtual fields aren't enough).......................................................... 13 Section 7.11. The Container needs these TWO things to know you have a CMP field "title"....................................................... 13 Section 7.12. Persistent CMP fields in the DD.............................................................................................................................. 14 Section 7.13. there are no Dumb Questions.................................................................................................................................. 14 Section 7.14. Using relationships in your code............................................................................................................................. 15 Section 7.15. Defining relationships in your abstract persistence schema (in the DD)............................................................... 16 Section 7.16. Relationship definition for the Director-to-Movie relationship............................................................................. 17 Section 7.17. Sharpen your pencil................................................................................................................................................. 19 Section 7.18. Director-to-Movie relationship............................................................................................................................... 19 Section 7.19. Relationships can be one-way ( unidirectional)..................................................................................................... 20 Section 7.20. The dark side of a unidirectional (one-way) relationship...................................................................................... 21 Section 7.21. Cascade delete can propagate.................................................................................................................................. 22 Section 7.22. Director-to-Movie relationship............................................................................................................................... 22 Section 7.23. Movie-to-Trailer relationship................................................................................................................................. 22 Section 7.24. The abstract schema> element is in the element and the is in the
Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 7. When Beans Relate
Section 7.55. COFFEE CRAM....................................................................................................................................................... 60
Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 7. When Beans Relate
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9OU CAN USE IT TO LOOK UP A MOVIE /NCE YOU HAVE A MOVIE YOU CAN USE IT TO LAUNCH THE MOVIE TRAILER 9OU CAN DO ALL KINDS OF SEARCHES TO SAY lND ALL SCI l MOVIES OR lND ALL ACTION MOVIES BY A SPECIlC DIRECTOR 7E CAN MAKE BEANS FOR -OVIE 4RAILER AND $IRECTOR "UT HOW DO THEY MAP TO THE DATABASE !ND HOW DO THEY RELATE TO ONE ANOTHER
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?MVMMLZMTI\QWV[PQX[JM\ _MMV\PM5W^QMJMIV IVL\PM, QZMK\WZJMIV 7E WANT THE -OVIE BEAN TO HAVE A REFERENCE TO ITS MATCHING $IRECTOR BEAN AND WE WANT TO DO ALL SORTS OF SEARCHES AGAINST THE -OVIE BEAN AND HAVE THE QUERIES USE THE $IRECTOR BEANS DATA AS WELL )N OTHER WORDS WE WANT TO MAKE IT EASY ON THE CLIENT AND ON THE DEVELOPER TO THINK IN A MORE NATURAL WAY RATHER THAN IN THE DATABASE EFl CIENT WAY THAT WAS USED TO DESIGN THE SCHEMA OF THE DATABASE 7HO WANTS THAT 2EMEMBER THIS IS THE // WORLD AND RELATIONAL DATABASES WHILE CRUCIAL TO YOUR BUSINESS ARE SO 7E WANT TO USE DATABASES WE JUST DONT WANT TO THINK LIKE DATABASES )F YOURE ONE OF THE LUCKY ONES WHO GETS TO USE AN // DATABASE AND ASSUMING THAT DATABASE STILL SOMEHOW MANAGES TO PERFORM WELL ENOUGH FOR YOUR NEEDS THEN YOU CAN JUST SMILE SMUGLY DURING THIS l RST SECTION
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Chapter 7. When Beans Relate
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?Pa[PW]TL\PM,QZMK\WZJMIJMIV' ?PaKIV¼\Q\R][\JMLI\I' 7HY NOT HAVE THE -OVIE BEAN SIMPLY GO TO THE DATABASE USING THE $IRECTORS FOREIGN KEY STORED AS A PERSISTENT lELD IN THE -OVIE BEAN AND GET THE $IRECTORS DATA "UT IF YOU MAKE THE DIRECTOR A BEAN AS WELL YOU GET TO THINK /.,9 IN OBJECTS EXCEPT DURING DEPLOYMENT WHEN YOU DO HAVE TO MAP FROM YOUR BEANS TO YOUR TABLES !ND YOU GET ALL THE BENElTS OF CONTAINER MANAGED PERSISTENCE AND SYNCHRONIZATION )MAGINE IF SOMEONE CALLS A SETTER METHOD TO CHANGE THE DIRECTORS OSCAR WINNING STATUS )F YOURE MANAGING THIS YOUD HAVE TO GET A *$"# CONNECTION AND SYNCHRONIZE THE DATABASE YOURSELF !ND OF COURSE YOUD HAVE TO KNOW WHEN IS THE RIGHT TIME ETC "UT IF ITS DIRECTOR IS ALSO A BEAN YOU CALL A SET7INNER METHOD AND YOURE DONE /H AND THERES ANOTHER COOL THING 9OU MIGHT DECIDE FOR EXAMPLE TO BANISH A SPECIlC DIRECTOR FROM YOUR DATABASE BECAUSE YOU THINK HIS MOVIES SUCK IN AN UNRECOVERABLE WAY .O PROBLEM DELETING THAT DIRECTOR OBVIOUSLY "UT THEN WHAT HAPPENS TO THE MOVIES (OW CAN YOU HAVE MOVIES IN THE DATABASE THAT DONT HAVE A DIRECTOR 7HAT IS THE DATABASE IS ALREADY SET UP IN SUCH A WAY THAT YOU ARENT ALLOWED TO HAVE A NULL VALUE FOR THE DIRECTOR COLUMN )N OTHER WORDS WHAT IF A MOVIE CANNOT EXIST IN THE DATABASE WITHOUT A DIRECTOR 9OU CAN HANDLE THIS BRAINLESSLY BY SETTING UP THE -OVIE TO $IRECTOR BEAN RELATIONSHIP IN SUCH A WAY THAT WHEN YOU DELETE A DIRECTOR FROM THE DATABASE ALL OF HIS MOVIES ARE AUTOMATICALLY DELETED 9OU DO THIS WITH ONE SIMPLE TAG IN THE DEPLOYMENT DESCRIPTOR AND 0//& 3OMEBODY CALLS REMOVE ON A DIRECTOR BEAN AND REMOVE WILL AUTOMATICALLY BE CALLED ON ALL OF THE MOVIE ENTITY BEANS THAT HAVE A REFERENCE TO THIS DIRECTOR AS THE VALUE OF THEIR DIRECTOR PERSISTENT lELD
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Chapter 7. When Beans Relate
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 11
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Movie has a multiplicity of ÒmanyÓ in its relationship with Director. That does NOT mean that Movie has ÒmanyÓ Directors... it means that Director has ÒmanyÓ Movies! So Director has a getMovies() that returns a Collection of Movies. And Director has a multiplicity of ÒoneÓ, which means that Movie will return just one Director.
! MULTIPLICITY OF ONE MEANS THE OBJECT YOURE RELATED TO HOLDS JUST ONE OF YOU $IRECTOR HAS A MULTIPLICITY OF ONE SO THE -OVIE OBJECT RELATED TO $IRECTOR RETURNS JUST A SINGLE $IRECTOR BEAN /+ TECHNICALLY THE COMPONENT INTERFACE OF $IRECTOR BUT YOU KNOW WHAT WE MEAN BY NOW ! MULTIPLICITY OF MANY MEANS THE OBJECT YOURE RELATED TO HOLDS A #OLLECTION OF YOU -OVIE HAS A MULTIPLICITY OF MANY SO THE $IRECTOR OBJECT RELATED TO -OVIE RETURNS A #OLLECTION OF -OVIE BEANS
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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,MNQVQVO^QZ\]ITNQMTL[NWZXMZ[Q[\MV\ LI\INQMTL[IVLZMTI\QWV[PQXNQMTL[ )N THE PREVIOUS CHAPTER WE LOOKED AT DElNING CONTAINER MANAGED lELDSYOU PUT IN A PAIR OF ABSTRACT GETTERS AND SETTERS 7E SAID A CONTAINER MANAGED lELD EXISTS SIMPLY BECAUSE YOU HAVE A GETTER AND SETTER FOR IT )T WORKS THE SAME WAY WITH CONTAINER MANAGED RELATIONSHIP #-2 lELDS 9OU DElNE A PAIR OF ABSTRACT GETTERS AND SETTERS BUT RATHER THAN SETTING AND RETURNING A VALUE THAT MAPS TO A COLUMN IN A TABLE YOU SET AND RETURN A REFERENCE TO ANOTHER ENTITY BEAN OR A #OLLECTION THAT WILL HOLD REFERENCES TO THE ENTITY BEAN 4HE RESTRICTIONS FOR #-2 lELDS ARE THAT THEY CAN REFER ONLY TO THE LOCAL COMPONENT INTERFACE OF THE ENTITY BEAN AND THAT IF THE METHOD RETURNS A #OLLECTION THE DECLARED TYPE CAN BE ONLY #OLLECTION OR 3ET NOT -AP ,IST ETC 4HE TERMINOLOGY IS A LITTLE CONFUSING BECAUSE BOTH #-0 AND #-2 lELDS ARE CONTAINER MANAGED PERSISTENT lELDS 4HEY MIGHT HAVE CALLED IT #-0#$ CONTAINER MANAGED PERSISTENT COLUMN DATA lELDS AND #-02 CONTAINER MANAGED PERSISTENT RELATIONSHIP lELDS /F COURSE PERSISTENCE ISNT RESTRICTED TO JUST RELATIONAL DATABASE SO WERE USING THE TERM hCOLUMNv A LITTLE LOOSELY "UT IN %*" ALL CONTAINER MANAGED PERSISTENT lELDS WERE #-0 lELDS BECAUSE THERE WAS NO CONCEPT OF PERSISTENT RELATIONSHIPS IN %*" #-0
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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4HE #ONTAINER FIGURES IT OUT BASED ON THE RETURN TYPE AND ARGUMENT OF THE ABSTRACT GETTERS AND SETTERS IN THE BEAN CLASS !ND THEY HAD BETTER MATCH )F YOU HAVE A GET,IMIT.UM THAT RETURNS AN INT YOU BETTER HAVE A SET,IMIT.UMINT I THAT TAKES AN INT
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Chapter 7. When Beans Relate
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Page 15
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=[QVOZMTI\QWV[PQX[QVaW]ZKWLM )N YOUR BEAN CODE YOU USE YOUR VIRTUAL RELATIONSHIP lELDS JUST AS YOU WOULD ANY OTHER GETTER AND SETTER 4HE ONLY DIFFERENCE BETWEEN USING A REAL lELD IE AN INSTANCE VARIABLE DECLARED IN YOUR CLASS AND A VIRTUAL lELD IS THAT YOU CAN ACCESS YOUR VIRTUAL lELDS ONLY BY CALLING THE ABSTRACT GETTERS AND SETTERS WHICH THE #ONTAINER IMPLEMENTS AT DEPLOY TIME 4HE ONLY NEW RESTRICTION IS THAT A RELATIONSHIP lELD CAN BE ONLY A LOCAL COMPONENT INTERFACE TYPE 9OU CANT HAVE A #-2 RELATIONSHIP lELD THAT USES A BEANS 2EMOTE INTERFACE
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type of a The argument and return ays another alw is CMR Òvirtual ÞeldÓ be a ST MU it and e, typ n bea Entity virtual a e hav Õt can You !! local interface ace. erf int ote Þeld to the entityÕs Rem
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ector to a Now we can return the Dir ct getter. tra abs the ing call client, by
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We can also do the wo client, if we donÕt wantrk on behalf of the Director reference to thto expose the real e client. In fact, thatÕs how weÕre going to Director is a local int do it, because the is going to have Remoteerface, but the Movie clients.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 7. When Beans Relate
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ionship has Every relawto beans. exactly t
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 7. When Beans Relate
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This is a made-up name! ItÕs choose to call the ROLE. simply what you We could have called it ÒDirectorRoleÓ or any thi participant weÕre talking ng that tells us which about. Remember, this does NOT say how many participant the Director bean will have of the other ... it says how many of THIS bean the OTHER part Movie will have only ONE Director. ner will have.
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We can use any role-name we want, but sooner or later the Container must know EXACTLY which bean weÕre talking about. Put the beanÕs which is just a label telling the Container where to Þnd this beanÕs real deÞnition in the section of the DD. This MUST match an in the DD.
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This must match a Òvirtual ÞeldÓ in the bean class for getMovies() / setMovies ()
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Remember, this is just a name for your own (or the App Assembler or a toolÕs) use. It means nothing in your Java code. This means Director will have MANY of type (Movie). Se we expect that Directorthis have a CMR Þeld with a Collection type will rather than a single Movie This MUST match the for where you deÞned the Movie entity bean in the section of the DD.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 7. When Beans Relate
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Page 19
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 7. When Beans Relate
Page 23
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 24
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Collection or Set (NOT List, HMEUHODWLRQVKLSUROH! HMEUHODWLRQVKLSUROHQDPH!0RYLH%HDQ HMEUHODWLRQVKLSUROHQDPH! PXOWLSOLFLW\!0DQ\ PXOWLSOLFLW\! FDVFDGHGHOHWH! MovieBean says, ÒYou can te UHODWLRQVKLSUROHVRXUFH! me when you delete my Directdele HMEQDPH!0RYLH%HDQ HMEQDPH! orÓ UHODWLRQVKLSUROHVRXUFH! FPU¿HOG! FPU¿HOGQDPH!GLUHFWRU FPU¿HOGQDPH! FPU¿HOG! HMEUHODWLRQVKLSUROH! use the Director has a HMEUHODWLRQ!
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 25
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our tent Þelds, by calling Here we set our perWesis must NOT try to reference abstract setters. RELATIONSHIPS. That has to our own persistent been inserted, and that happens wait until WE have eate() completes. only AFTER ejbCr
SXEOLFYRLGHME3RVW&UHDWH 6WULQJPRYLH,'6WULQJWLWOHLQW\HDU6WULQJJHQUH 6WULQJGLUHFWRU,' WKURZV&UHDWH([FHSWLRQ^ WU\^ ,QLWLDO&RQWH[WFW[ QHZ,QLWLDO&RQWH[W 'LUHFWRU+RPHGLU+RPH 'LUHFWRU+RPH FW[ORRNXS ³MDYD FRPSHQYHME'LUHFWRU+RPH´ 'LUHFWRUGLU GLU+RPH¿QG%\3ULPDU\.H\ GLUHFWRU,' VHW'LUHFWRU GLU `FDWFK ([FHSWLRQH[ Now itÕs safe to assign our persistent relationship ^KDQGOHH[FHSWLRQ` Þeld for Director. We lookup the Director (using `
the directorID parameter from create) and call our abstract setter to assign this Director.
SXEOLF6WULQJHME+RPH/LVW0RYLHV%\'LUHFWRU$QG*HQUH 6WULQJGLU,'6WULQJJHQUH ^ 6WULQJOLVW QXOO WU\^ &ROOHFWLRQF HME6HOHFW*HW0RYLHV%\'LUHFWRU$QG*HQUH GLU,'JHQUH ,WHUDWRULW FLWHUDWRU ZKLOH LWKDV1H[W ^ r the client to ss method fo the OLVW LWQH[W A home busine all the movies that Þtthat d of ho t ` lis et m a get s. an ejbSelect `FDWFK ([FHSWLRQH[ ^H[SULQW6WDFN7UDFH ` query. We usole lection of String objecte UHWXUQOLVW th C t a le s e rn w tu , d re etho ` ase code! ing a select m
ab By us te all the dat Container wri
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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HQWLW\EHDQUHODWLRQVKLSV SXEOLF6WULQJHME+RPH/LVW$OO0RYLHV ^ 6WULQJOLVW QXOO WU\^ ess method &ROOHFWLRQF HME6HOHFW*HW$OO0RYLHV Another home businme thod to Þnd ,WHUDWRULWD FLWHUDWRU t ec sel a s that use ZKLOH LWDKDV1H[W ^ returns a t ec sel is all movies. Th 0RYLHPRYLH 0RYLH LWDQH[W ovie objects, M Collection of actuhal it and pull out OLVW ³³PRYLHJHW0RYLH7LWOH ug ro th lk so we wa ` can return a the titles, so thatcliweent. `FDWFK ([FHSWLRQH[ ^KDQGOHH[FHSWLRQ` big String to the UHWXUQOLVW ` SXEOLF6WULQJJHW0RYLH7LWOH ^ Two exposed business methods from UHWXUQJHW7LWOH the component interface... ` SXEOLF6WULQJJHW0RYLH'LUHFWRU1DPH ^ UHWXUQJHW'LUHFWRU JHW'LUHFWRU1DPH ` SXEOLFDEVWUDFW6WULQJJHW0RYLH,' SXEOLFDEVWUDFWYRLGVHW0RYLH,' 6WULQJL SXEOLFDEVWUDFW6WULQJJHW7LWOH SXEOLFDEVWUDFWYRLGVHW7LWOH 6WULQJW SXEOLFDEVWUDFWLQWJHW
We have FIVE virtual Þelds: four CMP Þelds and one CMR Þeld for Director.
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The two select methods are declared as abstract methods. The Collection doesnÕt say WHAT the methods will return... but weÕll tell the Container that one will return a Collection of Movies and one a Collection of Strings.
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The rest are regular old callback methods.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Whoa! There are three Þn werenÕt in the bean cla der methods that ss... remember, the Cont ainer implements your Þnder me ANYTHING about Þnde thods--you donÕt put rs You put them ONLY in in your bean class code. the home. (well, thatÕs not complet ely have to tell the Contain true...somewhere you er HOW to implement th Þnders, which brings us e to the next page...)
art with methods all st in the ss ne si bu e m eyÕre The ho HomeÓ when th the preÞx Òejb e home, they donÕt have bean class. In th that preÞx.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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5IXXQVONZWUIJ[\ZIK\[KPMUI\WIZMITLI\IJI[M 3OONER OR LATER YOU HAVE TO TELL THE #ONTAINER HOW AND WHERE TO MANAGE YOUR PERSISTENT DATA 4HIS HAPPENS OUTSIDE THE DEPLOYMENT DESCRIPTOR IN A VENDOR SPECIlC WAY 4HAT MEANS OF COURSE THAT YOURE NOT TESTED ON IT IN THE EXAM %VERY VENDOR HAS THEIR OWN MECHANISM BUT YOULL USUALLY GET SOME SORT OF A '5) WHERE IF YOURE LUCKY YOU CAN TELL THE #ONTAINER TO CONNECT TO A SPECIlC DATABASE AND THEN YOULL DRAG AND DROP OR DRAW CONNECTIONS FROM #-0 lELDS TO COLUMNS IN ONE OR MORE TABLES "ECAUSE THIS MAPPING HAPPENS OUTSIDE OF %*" IN THE SERVER THERES NOT MUCH WE CAN SAY ABOUT IT 4HE PART WERE MOST INTERESTED IN IS MAPPING FROM ABSTRACT QUERIES TO 2%!, QUERIES AND THAT HAPPENS IN A VERY COOL WAY USING A VENDOR INDEPENDENT QUERY LANGUAGE JUST FOR YOUR ENTITY BEAN QUERIES %*" 1, 7ELL LOOK AT THAT ON THE NEXT PAGE DEVWUDFWVFKHPDQDPH!0RYLH6FKHPD DEVWUDFWVFKHPDQDPH! FPS¿HOG! ¿HOGQDPH!JHQUH ¿HOGQDPH! FPS¿HOG! FPS¿HOG! ¿HOGQDPH!PRYLH,' ¿HOGQDPH! FPS¿HOG! FPS¿HOG! ¿HOGQDPH!\HDU ¿HOGQDPH! FPS¿HOG! FPS¿HOG! ¿HOGQDPH!WLWOH ¿HOGQDPH! FPS¿HOG! SULPNH\¿HOG!PRYLH,' SULPNH\¿HOG!
Notice that weÕre not ma column (the one that ke pping the Director ID ep the Director table) be s the foreign key into cause we donÕt HAVE a persistent CMP Þeld fo r that, when we can have the Director ID. Why do the real Director, as an entity bean, instead? Th at comes in, but we donÕt Õs where our CMR Þeld map that to a database. Relationships happen by ma the part tching up two BEANS in of the DD.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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%*" 1, IS A PORTABLE QUERY LANGUAGE THAT LETS YOU WRITE 31, LIKE STATEMENTS WRITE INTO THE DEPLOYMENT DESCRIPTOR 9OU PUT THEM IN THE 8-, AND WITHOUT HAVING TO KNOW ANYTHING ABOUT THE REAL DATABASE !S A "EAN 0ROVIDER YOU CAN HAPPILY WRITE ALL THE QUERIES YOU WANT TRUSTING THAT THE $EPLOYER WILL IN THE END MAP YOUR #-0 lELDS TO REAL TABLES AND DATA !LL WE CARE ABOUT HERE IS WRITING OUR QUERIES TO MATCH THE METHODS WEVE CHOSEN TO EXPOSE TO THE CLIENT IN THE HOME AND COMPONENT INTERFACES 3ELECT METHODS ARE HERE SIMPLY TO MAKE YOUR LIFE EASIER BY LETTING THE #ONTAINER BUILD THE REAL DATABASE ACCESS CODE FROM YOUR QUERIES 3O THE PROCESS IS USUALLY SOMETHING LIKE 7RITE A HOME BUSINESS METHOD )MPLEMENT THE HOME BUSINESS METHOD TO CALL THE EJB3ELECT METHOD THAT DOES THE REAL DATA ACCESS $ECLARE THE ABSTRACT SELECT METHOD IN YOUR BEAN CLASS 7RITE THE %*" 1, FOR THE SELECT QUERY
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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-2*94NWZ\PM5W^QM*MIV ,ETS LOOK AT THE %*" 1, FOR ALL THE QUERIES THE -OVIE"EAN NEEDS $ONT WORRY IF YOURE NOT UNDERSTANDING ALL OF IT AFTER WE WALK THROUGH THE EXAMPLES WELL EXPLORE THE DIFFERENT PIECES IN DETAIL AND WORK OUT THE SYNTAX )F YOU KNOW 31, MOST OF THIS WILL BE FAMILIAR ALTHOUGH THERE ARE FEW DIFFERENCES YOULL SEE )F YOU DONT KNOW 31, THATS /+ 7ELL GET YOU STARTED WRITING QUERIES AND YOU CAN USE THE SPEC TO LEARN MORE ABOUT THE %*" 1, LANGUAGE 4HE EXAM EXPECTS YOU TO KNOW JUST THE BASICS OF %*" 1,
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This says ÒReturn what eve representing.Ó In this ex r ÔmÕ is am to represent MovieSch ple, ÔmÕ is said ema which really means the Movie entit y be Þrst part says, ÒGive me an type. So this Movie beansÓ.
... ÒLet ÔmÕ ring a variable the Movie la ec d e lik st a from This is ju abstract schem e, ÒLet represent the n REALLY think of it lik type. ca e bean. But you e Movie component interfac means, Y th L t L A en E es R ÔmÕ repr ie beans. So it ov M s, d or w r an. In othe ent a Movie be ÒLet ÔmÕ repres
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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=[QVOIVWX\QWVIT?0-:-KTI][M 4HIS EXAMPLE CONSTRAINS THE OBJECTS RETURNED FROM THE SEARCH BY ADDING A 7(%2% CLAUSE THAT SAYS WHAT EXTRA CRITERIA THE OBJECTS HAVE TO MEET BEFORE THEY QUALIFY FOR hTHINGS THAT CAN BE RETURNED FROM THE QUERYv 4HE 7(%2% CLAUSE IS YOUR WAY OF SAYING h$ONT JUST GIVE ME !.9 OLD -OVIE ) WANT /.,9 THE MOVIES THATv
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the CMP Þeld in ÒgenreÓ must behich means you can Movie bean, w re() / setGenre() Þnd a getGen the bean class method pair in
this means the Þrst parameter to the method the This says we want the t en es pr re Õ ly Ôm to on Let type of whatever ÔmÕ tubean pe ovies returned rns Movie bean ty restrict the M CMP Þeld ÒgenreÓ out to be... e those where th t parameter of the rs Þ matches the he Ò1Ó means the Þrst T d select metho Òm.genreÓ uses the dot he T parameter. a ÒpathÓ ator to make iented er op on ti ga vi na in an object-or that navigates the left hand operand :KDWLWUHDOO\VD\V eÑ way. ItÕs simpl e right hand is a th d ³*LYHPHDOOWKH0RYLHEHDQVWKDWDUHLQWKH an almost is a type, JHQUHPDWFKLQJWKH¿UVWSDUDPHWHUWRWKH that type. ItÕs ntax to of d el Þ r be sy em m a HME6HOHFW*HW$OO0RYLHVPHWKRG´ ing regular Jav exactly like us enreÓ, where genre is an .g say, ÒmyMovie (in this case, a virtual le ab ri va instance .) d el Þ nt persiste
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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6I^QOI\QVO\WIVW\PMZZMTI\MLJMIV 4HIS EXAMPLE IS FOR A lNDER METHOD SO YOU WONT lND IT IN THE BEAN CLASS REMEMBER YOU DECLARE ABSTRACT METHODS FOR ONLY THE SELECT METHODS NOT THE lNDERS 4HE #ONTAINER USES YOUR HOME INTERFACE TO lGURE OUT WHAT THE lNDERS ARE AND THEN ITS UP TO YOU TO WRITE THE %*" 1, FOR THE lNDERS 9OU CAN USE THE DOT OPERATOR TO NAVIGATE NOT JUST TO A #-0 lELD IN THE BEAN BUT TO ANOTHER lELD WITHIN A BEAN REFERENCED IN A #-2 lELD )N OTHER WORDS )F -OVIE HAS A REFERENCE TO A $IRECTOR AND THEYRE IN A RELATIONSHIP YOU CAN USE THE -OVIE TO GET TO THE $IRECTOR TO ASK FOR A #-0 VALUE FROM THE $IRECTOR
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ns Òthe m.director mea ectorÕ in CMR Þeld Ôdir Ó the Movie bean
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o you know? ... and what dthat ÔmÕ t It turns ou ovie bean means the M
restrict the Movies returned to only those where the MovieÕs Director has a CMP ÒdegreesÓ Þeld with a value that matches the Þrst parameter of the Þnder.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 34
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ng, with all rns a single Stri query. tu re d ho et m s Thi that match the the Movie titles
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this is different! WeÕre returning just Movie titles, not Movie objects 6(/(&7PWLWOH)5200RYLH6FKHPDP
the ÒgenreÓ m.genre means the Movie bean in CMP Þeld
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This restricts the matc Movies with a Director hes to only those equal to the Þrst para who has an ID meter to the method
AND whose Movie genre value equals the second parameter to the method
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 35
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6(/(&7 4HE 3%,%#4 CLAUSE SAYS WHAT KIND OF THING THIS QUERY WILL RETURN )T CAN BE ONLY ONE OF THESE TWO
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 7. When Beans Relate Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
Table of Contents Chapter 8. Getting the Message................................................................... 1 Section 8.1. OBJECTIVES............................................................................................................................................................... 2 Section 8.2. Imagine this scenario.................................................................................................................................................. 3 Section 8.3. Too bad these guys aren't message-driven beans....................................................................................................... 5 Section 8.4. Message-driven bean class........................................................................................................................................ 10 Section 8.5. Writing a message-driven bean: your job as Bean Provider..................................................................................... 11 Section 8.6. Sharpen your pencil................................................................................................................................................... 11 Section 8.7. Notice something missing from the code?................................................................................................................ 13 Section 8.8. Complete DD for a message-driven bean................................................................................................................. 13 Section 8.9. Topics and Queues.................................................................................................................................................... 14 Section 8.10. There are no: Dumb Questions............................................................................................................................... 16 Section 8.11. Only ONE bean per pool gets a copy of a topic message......................................................................................... 17 Section 8.12. With a queue, only one bean gets the message. Period.......................................................................................... 18 Section 8.13. MessageDrivenContext............................................................................................................................................ 19 Section 8.14. MessageDrivenContext........................................................................................................................................... 20 Section 8.15. message acknowledgement..................................................................................................................................... 22 Section 8.16. That's all well and good, but let's go back and see how our earlier scenario ended.............................................. 23 Section 8.17. Off the path: Think about it..................................................................................................................................... 24 Section 8.18. COFFEE CRAM....................................................................................................................................................... 27 Section 8.19. COFFEE CRAM....................................................................................................................................................... 30
Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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there are no
Dumb Questions
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(OW DOES *-3 lT INTO ALL THIS !ND IF ) HAVE A MESSAGE DRIVEN BEAN WHERE DO ) GET THE MESSAGING SERVICE
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Q:
#AN ) GET MESSAGES FROM NON *-3 MESSAGING SERVICES
A:
.OT RIGHT NOW IN %*" BUT THEY THE INFAMOUS *%% TEAM HOPE TO ADD THAT CAPABILITY SOME DAY
Q:
7HY DOESNT THE -ESSAGE$RIVEN"EAN JUST EXTEND THE -ESSAGE,ISTENER INTERFACE 4HAT WAY YOU WOULDNT HAVE TO IMPLEMENT BOTH INTERFACES
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3EE YOUR PREVIOUS QUESTION 4HE *%% TEAM DIDNT WANT TO LOCK ALL MESSAGE DRIVEN BEANS INTO BEING *-3 LISTENERS /NE DAY THERE MIGHT BE MANY KINDS OF LISTENER INTERFACES FOR DIFFERENT MESSAGING TYPES
Q:
!RE MESSAGES GUARANTEED TO COME IN ORDER 7ILL ) ALWAYS GET THE lRST ONE lRST
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.O 9OU BETTER NOT DEPEND ON IT OR "AD 4HINGS -IGHT (APPEN &OR EXAMPLE YOU MIGHT GET THE h#ANCEL THE /RDERv MESSAGE BEFORE YOU GET THE h0LACE THE /RDERv MESSAGE $ESIGN YOUR SYSTEM AND CODE YOUR BEAN ON THE ASSUMPTION THAT MESSAGE ORDER IS NOT STRICTLY GUARANTEED
Q:
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7VTa76-JMIVXMZXWWTOM\[ IKWXaWNI\WXQKUM[[IOM )F YOU HAVE SAY THE 7ELCOME"EAN SUBSCRIBED TO THE .EW#USTOMER TOPIC WHEN A NEW MESSAGE IS PUBLISHED TO THAT TOPIC THE #ONTAINER WILL CHOOSE ONLY ONE BEAN FROM THE 7ELCOME"EAN POOL TO GET THE MESSAGE 2EMEMBER THE #ONTAINER KEEPS A SEPARATE POOL OF BEANS FOR EACH HOME AND EVERY DEPLOYED BEAN TYPE GETS ITS OWN HOME 4HE #ONTAINER DOESNT PUT ALL MESSAGE DRIVEN BEANS INTO ONE POOL EVEN IF THEYRE SUBSCRIBED TO THE SAME TOPICS "UT IF THERE ARE MULTIPLE BEAN TYPES SUBSCRIBED TO THAT TOPIC ONE BEAN FROM EACH OF THOSE POOLS WILL ALSO GET THE MESSAGE )N THIS PICTURE BOTH THE 7ELCOME"EAN AND THE .EW3ALES"EAN ARE SUBSCRIBERS TO THE .EW#USTOMER TOPIC SO THE #ONTAINER SELECTS ONE BEAN FROM EACH POOL TO GET THE MESSAGE
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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?Q\PIY]M]MWVTaWVMJMIV OM\[\PMUM[[IOM8MZQWL )F YOU HAVE A QUEUE FOR MESSAGES REQUESTING THAT A NEW CUSTOMER BE PROCESSED ONLY ONE BEAN FROM THE POOL ASSOCIATED WITH THAT QUEUE WILL GET THE MESSAGE 4HATS IT /H AND DONT EVEN THINK ABOUT ASKING WHAT HAPPENS IF YOU HAVE MORE THAN ONE BEAN TYPE POOL ASSOCIATED WITH THAT QUEUE "UT IF YOU PERSIST WELL TELL YOU THAT *-3 DOESNT DElNE WHAT HAPPENS WHEN THERE IS MORE THAN ONE CONSUMER FOR A PARTICULAR QUEUE 4HAT MEANS THERES NO WAY TO KNOW HOW THE MESSAGES MIGHT BE DISTRIBUTED AMONG THE DIFFERENT QUEUE CONSUMERS -AYBE THE MESSAGING SERVICE WILL JUST PICK ONE AT RANDOM "UT MAYBE IT WONT -AYBE ITLL JUST PICK THE lRST ONE IN A PROPERTIES lLE AND SEND EVERYTHING THERE 3O JUST DONT DO IT
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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5M[[IOM,ZQ^MV+WV\M`\ 4HE SERVER MAKES MESSAGE DRIVEN BEANS VIRTUALLY THE SAME WAY IN WHICH IT MAKES STATELESS SESSION BEANS #ALL THE BEANS CONSTRUCTOR MUST BE NO ARG #ALL THE BEANS CONTEXT SETTER #ALL THE BEANS EJB#REATE METHOD )N FACT THE l RST TWO STEPS ARE THE SAME FOR ALL BEAN TYPES 4HE CONTEXT SETTER ALWAYS COMES IMMEDIATELY AFTER THE BEANS CONSTRUCTOR AND AT SOME POINT BEFORE EJB#REATE !ND OF COURSE AN ENTITY BEAN MIGHT NEVER GET AN EJB#REATE CALL IF THERE ARENT ANY CLIENTS TRYING TO INSERT NEW ENTITIES INTO THE DATABASE 3O WHAT CAN A MESSAGE DRIVEN BEAN DO WITH ITS CONTEXT 7E THINK ITS TIME FOR YOU TO l GURE THAT OUT 7E CAN GUARANTEE THERE WILL BE QUESTIONS ON THE EXAM RELATED TO WHAT A MESSAGE DRIVEN BEAN CAN AND CANNOT DO WITH ITS CONTEXT )N FACT YOULL l ND THESE QUESTIONS SCATTERED THROUGHOUT THE OBJECTIVES NOT JUST IN THE MESSAGE DRIVEN BEAN OBJECTIVES n 1UESTIONS FROM THE TRANSACTIONS EXCEPTIONS AND SECURITY OBJECTIVES MIGHT INVOLVE A MESSAGE DRIVEN BEAN AND ITS CONTEXT
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
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Page 21
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
Page 22
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5M[[IOMIKSVW_TMLOMUMV\ 9OU DONT WANT MESSAGES GETTING LOST )F YOU HAVE A CRUCIAL MESSAGE ON THE QUEUE AND THE ONE BEAN WHO GETS IT CANT COMMITOR WORSE THROWS AN EXCEPTION AND DIESWHAT HAPPENS TO YOUR CRITICAL MESSAGE 4HATS THE POINT OF ACKNOWLEDGEMENT 4HE #ONTAINER TELLS THE MESSAGING SERVICE NOT THE ORIGINAL PRODUCER THAT THE MESSAGE WAS DELIVERED AND EVERYTHING IS lNE "UT IF LATER WHILE THE CONSUMER THE MESSAGE DRIVEN BEAN IS PROCESSING THE MESSAGE A "AD 4HING HAPPENS THE #ONTAINER CAN TELL THE MESSAGING SERVICE TO PUT THE MESSAGE BACK IN THE QUEUE (OW DOES THE #ONTAINER REALLY KNOW THAT SOMETHING WENT WRONG 4WO WAYS AND ITS YOUR CHOICE AS A "EAN 0ROVIDER
7KHWUDQVDFWLRQVWDWXV -ESSAGE ACKNOWLEDGEMENT IS TIED TO WHETHER THE TRANSACTION COMMITS OR ROLLS BACK )F THE TRANSACTION ROLLS BACK THE MESSAGE GOES BACK ON THE QUEUE 9OU GET THIS BEHAVIOR FOR BEANS THAT USE CONTAINER MANAGED TRANSACTION DEMARCATION WELL COVER TRANSACTIONS IN THE NEXT CHAPTER
25
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
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Page 23
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
Page 24
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6HWWLQJWKHDFNQRZOHGJHPHQWPRGH )F YOU $/ USE "-4 YOU HAVE TWO CHOICES FOR HOW THE #ONTAINER SENDS AN ACKNOWLEDGEMENT TO THE MESSAGING SERVICE 4HE CHOICES ARE DFNQRZOHGJHPRGH!$XWRDFNQRZOHGJH DFNQRZOHGJHPRGH! /2 DFNQRZOHGJHPRGH!'XSVRNDFNQRZOHGJH DFNQRZOHGJHPRGH! 4HIS DOESNT CHANGE THE #ONTAINERS BEHAVIOR OF WHETHER IT DECIDES TO DO THE ACKNOWLEDGEMENTFOR A "-4 BEAN ITS ALWAYS BASED ON WHETHER THE METHOD COMPLETES 4HE ACKNOWLEDGE MODE IS SIMPLY A WAY TO TWEAK HOW THE #ONTAINER SENDS THE ACKNOWLEDGEMENT 7ITH $UPS OK ACKNOWLEDGE YOURE TELLING THE #ONTAINER THAT YOU DONT MIND IF ITS KIND OF SLOW WITH THE ACKNOWLEDGEMENT TO THE MESSAGE SERVICE THAT YOU DONT MIND IF YOU GET DUPLICATE MESSAGES hDUPS OKv 4HIS LETS THE #ONTAINER TAKE WHATEVER TIME IT WANTS TO DO THE ACKNOWLEDGEMENT AND IT MIGHT MAKE THE SERVER MORE EFlCIENT BUT AT THE RISK OF DUPLICATE MESSAGES BECAUSE THE POOR MESSAGING SERVICE DIDNT GET AN ACKNOWLEDGEMENT QUICKLY ENOUGH
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
Page 25
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
Page 26
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call isCallerInRole() (thereÕs no client!)
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call getEJBHome() (thereÕs no client view, so thereÕs no home or component interface)
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
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Page 27
PHVVDJHGULYHQEHDQV
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7HATS TRUE ABOUT MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
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7HICH ARE VALID SIGNATURES FOR METHODS IN A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
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Page 29
PHVVDJHGULYHQEHDQV
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7HATS TRUE ABOUT #ONTAINER SUPPORT FOR MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
R! 4HE #ONTAINER MUST SUPPORT THE DEPLOYMENT OF A MESSAGE DRIVEN BEAN AS THE CONSUMER OF A *AVA-AIL QUEUE
R" 4HE #ONTAINER IS ./4 REQUIRED TO SUPPORT TRANSACTION SCOPING FOR MESSAGE DRIVEN BEANS
R# 4HE #ONTAINER GUARANTEES lRST IN lRST DELIVERED MESSAGE PROCESSING R$ 4HE #ONTAINER MUST ENSURE THAT THE BEAN INSTANCES ARE NON REENTRANT
9
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R! 4HE BEAN PROVIDER MUST GUARANTEE THAT THE BEAN IS ASSOCIATED WITH A SPECIlC QUEUE OR TOPIC
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
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Page 30
PRFNH[DPDQVZHUV
0RFN([DP$QVZHUV 1
(spec: 311-312)
7HATS TRUE ABOUT MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
R! ! MESSAGE DRIVEN BEAN HAS A HOME INTERFACE BUT NO COMPONENT INTERFACE
- MDBs have NO client view
R" ! CLIENT NEVER KNOWS A MESSAGE DRIVEN BEANS IDENTITY R# ! CLIENT SEES A MESSAGE DRIVEN BEAN AS A *AVA-AIL MESSAGE CONSUMER R$ 4HE LIFETIME OF A MESSAGE DRIVEN BEAN IS CONTROLLED BY THE CONTAINER
2
7HICH INTERFACES MUST BE IMPLEMENTED IN A MESSAGE DRIVEN BEAN CLASS OR IN ONE OF ITS SUPERCLASSES #HOOSE ALL THAT APPLY
(spec: 314-315)
R! MDYD[MPV0HVVDJH R" MDYD[MPV0HVVDJH/LVWHQHU - this is where the onMessage() method is deÞned R# MDYD[MPV0HVVDJH&RQVXPHU R$ MDYD[HME0HVVDJH'ULYHQ%HDQ R% MDYD[HME0HVVDJH'ULYHQ&RQWH[W
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(spec: 319)
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 31
PHVVDJHGULYHQEHDQV
4
7HICH ARE VALID SIGNATURES FOR METHODS IN A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
(spec: 324)
R! SXEOLFYRLGRQ0HVVDJH R" SXEOLFYRLGHME&UHDWH R# SXEOLFVWDWLFYRLGRQ0HVVDJH R$ SXEOLFYRLGHME&UHDWH MDYD[MPV0HVVDJHP R% SXEOLFYRLGRQ0HVVDJH MDYD[MPV0HVVDJHP R& SXEOLFYRLGRQ0HVVDJH MDYD[MPV0HVVDJHP WKURZV MDYDUPL5HPRWH([FHSWLRQ
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(spec: 319, 324)
R! HME&UHDWH R"HME5HPRYH sage R# RQ0HVVDJH - takes a mes R$ VHW0HVVDJH'ULYHQ&RQWH[W - takes a context
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 8. Getting the Message
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Page 32
PRFNH[DPDQVZHUV
8
(spec: 325-326)
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Chapter 8. Getting the Message Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
Table of Contents Chapter 9. The Atomic Age.......................................................................... 1 Section 9.1. OBJECTIVES............................................................................................................................................................... 2 Section 9.2. An EJB transaction is an atomic unit of work............................................................................................................ 3 Section 9.3. The ACID test.............................................................................................................................................................. 4 Section 9.4. Distributed transactions: two-phase commit............................................................................................................. 5 Section 9.5. How it works in EJB.................................................................................................................................................... 6 Section 9.6. Some transactions don't propagate............................................................................................................................ 7 Section 9.7. How do I make (or get) a transaction?....................................................................................................................... 8 Section 9.8. Transaction-related methods are in two interfaces................................................................................................... 9 Section 9.9. BRAIN POWER........................................................................................................................................................... 9 Section 9.10. Making a BMT transaction...................................................................................................................................... 10 Section 9.11. Call stack of the checkOut() method........................................................................................................................ 11 Section 9.12. Sharpen your pencil................................................................................................................................................. 12 Section 9.13. Things you must NOT do with BMT........................................................................................................................ 13 Section 9.14. BMT transactions are one way: they can propagate out to a CMT bean, but no other transaction can propagate in to a BMT bean................................................................................................................................................................................ 14 Section 9.15. What does it mean to suspend a transaction?......................................................................................................... 15 Section 9.16. The UserTransaction interface................................................................................................................................ 16 Section 9.17. setRollbackOnly( ): The sound of a transaction's death.......................................................................................... 17 Section 9.18. setRollbackOnly() lives in TWO interfaces............................................................................................................. 19 Section 9.19. getRollbackOnly():.................................................................................................................................................. 20 Section 9.20. BMT beans use getStatus() instead of getRollbackOnly()...................................................................................... 21 Section 9.21. BMT can be a really BAD idea. BMT hurts bean reuse.......................................................................................... 22 Section 9.22. Container-managed transactions........................................................................................................................... 23 Section 9.23. How attributes work............................................................................................................................................... 24 Section 9.24. Know your attributes.............................................................................................................................................. 25 Section 9.25. Transaction attributes that require a transaction.................................................................................................. 26 Section 9.26. Sharpen your pencil: Know your attributes........................................................................................................... 28 Section 9.27. Sharpen your pencil................................................................................................................................................ 29 Section 9.28. These are the methods you MUST mark with an attribute (for a CMT bean)...................................................... 30 Section 9.29. "Unspecified Transaction Context"......................................................................................................................... 31 Section 9.30. Burn these in........................................................................................................................................................... 32 Section 9.31. Overheard at: THE TiKiBEAN LoUNGE................................................................................................................ 33 Section 9.32. Marking transactions in the DD............................................................................................................................. 34 Section 9.33. DD example for CMT.............................................................................................................................................. 35 Section 9.34. More DD examples for CMT................................................................................................................................... 36 Section 9.35. Sharpen your pencil: Which methods need transaction attributes?..................................................................... 39 Section 9.36. Summary of Bean-managed demarcation............................................................................................................. 40 Section 9.37. Entity beans have ejbLoad( ) to stay synchronized, even if the transaction rolls back......................................... 42 Section 9.38. Session Synchronization: because session beans don't have ejbLoad and ejbStore............................................. 43 Section 9.39. SessionSynchronization "special moments".......................................................................................................... 44 Section 9.40. There are no Dumb Questions................................................................................................................................ 45 Section 9.41. Pool Puzzle............................................................................................................................................................... 46 Section 9.42. Pool Puzzle Solution................................................................................................................................................ 47 Section 9.43. COFFEE CRAM....................................................................................................................................................... 48 Section 9.44. COFFEE CRAM....................................................................................................................................................... 52
Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 16
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 20
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
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Page 21
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
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Page 22
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 28
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 29
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6KDUSHQ \RXU SHQFLO &OR THE EXAM AND BEAN DEVELOPER LIFE IN GENERAL YOU HAVE TO KNOW SOME 2%!,,9 IMPORTANT RULES ABOUT TRANSACTIONS AND IT WILL BE MUCH EASIER FOR YOU IF YOU TAKE THE TIME NOW TO FIGURE SOME OF THIS OUT FOR YOURSELF 5NDERSTANDING IS MUCH BETTER THAN MEMORIZING AND ITS NOT LIKE YOU DONT HAVE ENOUGH TO MEMORIZE AS IT IS 9OULL FIND ALL OF THESE QUESTIONS ANSWERED OVER THE NEXT FEW PAGES BUT YOU SHOULD REALLY TRY TO DO THIS FIRST
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 39
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 46
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 9. The Atomic Age
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Page 50
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Chapter 9. The Atomic Age
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)F A SET OF #-4 BEAN METHODS HAS THE FOLLOWING TRANSACTION ATTRIBUTES
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Chapter 9. The Atomic Age Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
Table of Contents Chapter 10. When beans go bad................................................................... 1 Section 10.1. OBJECTIVES............................................................................................................................................................. 2 Section 10.2. What can go wrong?.................................................................................................................................................. 3 Section 10.3. Remember, Java exceptions can be checked or unchecked..................................................................................... 4 Section 10.4. It's all about expectations.......................................................................................................................................... 5 Section 10.5. Exception pathways................................................................................................................................................... 6 Section 10.6. In EJB, exceptions come in two flavors: application and system............................................................................ 8 Section 10.7. With an Application Exception, the Container will.................................................................................................. 9 Section 10.8. With a System Exception, the Container will......................................................................................................... 10 Section 10.9. BRAIN POWER....................................................................................................................................................... 12 Section 10.10. Warning! RemoteException is checked, but not expected!.................................................................................. 13 Section 10.11. A Remote entity bean home interface declares application exceptions and one system exception (RemoteException)........................................................................................................................................................................ 14 Section 10.12. A local entity bean home interface declares only application exceptions............................................................. 14 Section 10.13. RemoteException goes to remote clients EJBException goes to local clients...................................................... 15 Section 10.14. there are no Dumb Questions................................................................................................................................ 16 Section 10.15. Bean Provider's responsibilities............................................................................................................................. 17 Section 10.16. Bean Provider's responsibilities............................................................................................................................ 18 Section 10.17. Bean Provider's responsibilities............................................................................................................................. 19 Section 10.18. Bean Provider's responsibilities............................................................................................................................ 20 Section 10.19. Bean Provider's responsibilities............................................................................................................................ 21 Section 10.20. there are no Dumb Questions............................................................................................................................... 21 Section 10.21. The Container's responsibilities............................................................................................................................ 22 Section 10.22. BRAIN POWER..................................................................................................................................................... 23 Section 10.23. Sharpen your pencil.............................................................................................................................................. 23 Section 10.24. The five standard EJB application exceptions..................................................................................................... 24 Section 10.25. The five standard application exceptions from the client's point of view............................................................ 25 Section 10.26. there are no Dumb Questions............................................................................................................................... 26 Section 10.27. Common system exceptions.................................................................................................................................. 27 Section 10.28. Common sysstem exceptions................................................................................................................................ 28 Section 10.29. Scenarios: what do you think happens?............................................................................................................... 32 Section 10.30. Sharpen your pencil.............................................................................................................................................. 33 Section 10.31. Scenario Summary................................................................................................................................................. 34 Section 10.32. Scenario Summary................................................................................................................................................ 35 Section 10.33. Scenario Summary................................................................................................................................................ 36 Section 10.34. Exercise.................................................................................................................................................................. 37 Section 10.35. Exercise................................................................................................................................................................. 38 Section 10.36. COFFEE CRAM..................................................................................................................................................... 39 Section 10.37. COFFEE CRAM..................................................................................................................................................... 42
Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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?IZVQVO :MUW\M-`KMX\QWVQ[KPMKSML J]\VW\M`XMK\ML .ORMALLY WHEN WE THINK OF EXPECTED VS UNEXPECTED EXCEPTIONS WE MAP IT TO CHECKED VS UNCHECKED EXCEPTIONS ! &ILE)/%XCEPTION IS EXPECTED ! .ULL0OINTER%XCEPTION IS NOT !NY DIRECT SUBCLASS OF %XCEPTION IS EXPECTED ! SUBCLASS OF 2UNTIME%XCEPTION IS NOT ! CHECKED EXCEPTION MUST BE HANDLED !N UNCHECKED EXCEPTION USUALLY WONT BE "UT THERES ONE BIG EXCEPTION TO THE WHOLE EXCEPTIONS AND EXPECTATIONS THINGJAVARMI2EMOTE%XCEPTION 2EMOTE%XCEPTION IS A CHECKED EXCEPTION OF COURSE SO THE CLIENT IS FORCED TO ACKNOWLEDGE A 2EMOTE%XCEPTION BY HANDLING IT WITH A TRYCATCH "UT UNLIKE THE OTHER CHECKED EXCEPTIONS A CLIENT SEES IN A BEANS INTERFACE 2EMOTE%XCEPTION IS STILL CONSIDERED UNEXPECTED /+ NOT EXACTLY UNEXPECTED BUT UNEXPECTED &ROM THE CLIENTS POINT OF VIEW THINK OF 2EMOTE%XCEPTION A KIND OF RUNTIME EXCEPTION ON THE REMOTE PART OF THE APPLICATION "ECAUSE THATS OFTEN WHAT IT MEANS ! .ULL0OINTER%XCEPTION ON THE SERVER MEANS A 2EMOTE%XCEPTION TO THE CLIENT ! $IVIDE"Y:ERO%XCEPTION ON THE SERVER MEANS A 2EMOTE%XCEPTION TO THE CLIENT ! #LASS#AST%XCEPTION ON THE SERVER MEANS A 2EMOTE%XCEPTION TO THE CLIENT 4HOSE ARE ALL UNCHECKED EXCEPTIONS ON THE SERVER BUT THEY PROPAGATE BACK TO THE CLIENT AS A CHECKED 2EMOTE%XCEPTION )N OTHER WORDS THE CLIENT HAS TO EXPECT THAT THE SERVER CAN THROW SOMETHING UNEXPECTED $OES THIS MEAN THAT EVERY 2EMOTE%XCEPTION ON THE CLIENT WAS ORIGINALLY TRIGGERED BY A BEAN GETTING A RUNTIME EXCEPTION .O ! BEAN MIGHT FOR EXAMPLE CATCH A CHECKED EXCEPTION AS PART OF ITS BUSINESS LOGIC AND THEN REALIZE IT CANT RECOVER !T THAT POINT THE BEAN TURNS WHAT WAS ORIGINALLY A CHECKED EXCEPTION FROM THE BEANS PERSPECTIVE TO AN UNCHECKED SYSTEM EXCEPTION BY WRAPPING AND RETHROWING IT AS AN %*"%XCEPTION WHICH ULTIMATELY SHOWS UP AS A 2EMOTE%XCEPTION ON THE REMOTE CLIENT
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Page 21
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4HATS RIGHT 9OU CAN THROW ONLY UNCHECKED EXCEPTIONS FROM A CONTAINER CALLBACK THAT IS NOT PART OF YOUR CLIENT VIEW 4HIS IS JUST PLAIN OLD *AVA YOU CANT THROW A CHECKED EXCEPTION FROM A METHOD THAT DOESNT DECLARE THE EXCEPTION AND SINCE THOSE INTERFACES DONT DECLARE ANY CHECKED EXCEPTIONS THAT YOU CAN USE YOURE STUCK WITH RUNTIME EXCEPTIONS 4HE ONLY THING YOU SHOULD THROW FROM ONE OF THE CONTAINER CALLBACKS OF 3ESSION"EAN %NTITY"EAN OR -ESSAGE$RIVEN"EAN IS AN %*"%XCEPTION
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Page 24
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Page 25
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Page 26
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!RENT YOU FORGETTING SOMETHING OBVIOUS HERE 7HERE DO THE REMOVE METHODS LIVE (OW ARE THEY EXPOSED TO THE CLIENT 4HATS RIGHT )N THE CLIENT INTERFACES 2EMEMBER THERE ARE THREE REMOVE METHODS AVAILABLE TO A REMOTE ENTITY BEAN CLIENT THE NO ARG IN THE %*"/BJECT INTERFACE AND THE REMOVE THAT TAKES A KEY AND THE REMOVE THAT TAKES A HANDLE IN THE %*"(OME INTERFACE ! LOCAL ENTITY BEAN CLIENT HAS TWO REMOVE METHODSTHE ONE IN %*"/BJECT AND THE ONE IN THE HOME THAT TAKES A PRIMARY KEY 3O THERES NOTHING YOU CAN DO TO HIDE THE REMOVE METHODS FROM A CLIENT BUT IF YOU DONT SUPPORT IT FROM YOUR BEAN THROW A 2EMOVE%XCEPTION FROM YOUR BEANS EJB2EMOVE METHOD AND THE #ONTAINER WONT GO THROUGH WITH THE REMOVE 4HIS IS YOUR WAY OF TELLING THE #ONTAINER h$ONT DO IT ) DONT CARE WHAT THE CLIENT SAYS DONT YOU DARE GO THROUGH WITH THE REMOVEv
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Page 27
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+WUUWV[a[\MUM`KMX\QWV[ "ESIDES THE STANDARD APPLICATION EXCEPTIONS FOR %*" THERE ARE SEVERAL IMPORTANT SYSTEM EXCEPTIONS ! FEW INCLUDING %*"%XCEPTION ARE PART OF THE *%% !0) BUT TWO OF THE MOST LIKELY SYSTEM EXCEPTIONS IN %*" INCLUDE JAVARMI.O3UCH/BJECT%XCEPTION AND JAVALANG)LLEGAL3TATE%XCEPTION
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Chapter 10. When beans go bad
Page 28
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4HE #ONTAINER THROWS THIS TO A BEAN IF THE BEAN CALLS A METHOD ON ITS CONTEXT THAT ISNT ALLOWED AT THAT TIME &OR EXAMPLE A SESSION BEAN CANT ASK ITS CONTEXT FOR A REFERENCE TO ITS %*" OBJECT WHILE IN THE SET3ESSION#ONTEXT METHOD )TS TOO EARLY ! BEAN CAN ALSO GET AN )LLEGAL3TATE%XCEPTION IF IT CALLS A TRANSACTION METHOD LIKE SET2OLLBACK/NLY OR GET2OLLBACK/NLY WHEN THERES NO TRANSACTION (-%([FHSWLRQ
4HE BEAN THROWS THIS TO TELL THE #ONTAINER A SYSTEM EXCEPTION HAS OCCURRED WHICH FORCES THE #ONTAINER TO ROLLBACK THE TRANSACTION LOG THE EXCEPTION KILL THE BEAN AND GIVE A LOCAL CLIENT THE %*"%XCEPTION AND A REMOTE CLIENT A 2EMOTE%XCEPTION "UT THE #ONTAINER CAN ALSO THROW THIS FOR A VARIETY OF OTHER REASONS WELL LOOK AT IN A MINUTE 1R6XFK2EMHFW/RFDO([FHSWLRQ
4HIS EXCEPTION IS KIND OF A LOCAL COMPANION TO JAVARMI.O3UCH/BJECT%XCEPTION 4HE #ONTAINER THROWS IT TO THE CLIENT WHEN THE CLIENT INVOKES A METHOD ON A LOCAL HOME OR COMPONENT INTERFACE BUT THERES NO UNDERLYING BEAN TO SUPPORT THE OBJECT 4HIS CAN HAPPEN FOR EXAMPLE IF THE BEAN HAS ALREADY BEEN REMOVED EITHER THROUGH A PREVIOUS CLIENT CALL TO REMOVE OR BECAUSE THE #ONTAINER KILLED THE BEAN DUE TO AN EXCEPTION STATEFUL BEAN TIMEOUT OR TO REDUCE THE SIZE OF THE POOL 1R6XFK(QWLW\([FHSWLRQ
9OU PROBABLY WONT SEE OR USE THIS EXCEPTION MUCH ESPECIALLY WITH #-0 BUT ITS FOR YOU TO THROW FROM YOUR BEAN CODE WHEN YOU WANT TO TELL THE #ONTAINER THAT THE ENTITY YOURE TRYING TO ACCESS IS NO LONGER IN THE DATABASE PERHAPS BECAUSE IT WAS REMOVED BY AN ADMIN APPLICATION 7UDQVDFWLRQ5HTXLUHG/RFDO([FHSWLRQ7UDQVDFWLRQ5HTXLUHG([FHSWLRQ
4HE #ONTAINER THROWS THIS TO THE CALLER WHEN THE CALLED METHOD HAS A TRANSACTION ATTRIBUTE OF MANDATORY BUT THERES NO TRANSACTION CONTEXT COMING IN WITH THE CALL )N OTHER WORDS ITS MANDATORY THAT THE CALLER INVOKES THE METHOD WITHIN AN EXISTING TRANSACTION AND IF THERE ISNT ONE THE APPROPRIATE 4RANSACTION2EQUIRED EXCEPTION IS THROWN DEPENDING ON WHETHER THE CLIENT IS LOCAL OR REMOTE 7UDQVDFWLRQ5ROOHGEDFN([FHSWLRQ7UDQVDFWLRQ5ROOHGEDFN/RFDO([FHSWLRQ
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Page 29
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/+ WE AGREE 4HE NAMES FEEL A LITTLE SHALL WE SAY ARBITRARY "UT REMEMBER THE .O3UCH/BJECT%XCEPTION CAME lRST )T WAS DESIGNED FOR THE SCENARIO WHERE THE CLIENT HAS A STUB TO A 2EMOTE OBJECT AND FOR WHATEVER REASON THE 2EMOTE OBJECT IS NO LONGER USABLE -IGHT HAVE BEEN A SERVER CRASH -IGHT BE THAT THE SERVICE ITSELF HAS BEEN UNDEPLOYED $OESNT MATTER !S FAR AS THE CLIENTS CONCERNED THE PHONE HAS BEEN DISCONNECTED OVER AT THE SERVER SIDE .O3UCH/BJECT,OCAL%XCEPTION WAS ADDED WHEN LOCAL CLIENT VIEWS WERE ADDED IN %*" 4HE CONCEPT IS SLIGHTLY DIFFERENT BECAUSE THE LOCAL CLIENT IS USING NOT A STUB BUT A REAL *AVA OBJECT REFERENCE "UT FROM THE CLIENTS PERSPECTIVE IT REALLY DOESNT MATTER WHETHER ITS LOCAL OR 2EMOTEA .O3UCH/BJECT WHATEVER EXCEPTION MEANS YOU CANT USE YOUR %*" OBJECT REFERENCE TO GET TO A BEAN 9OU HAVE TO GO BACK THROUGH THE HOME AND START OVER \RXDUHKHUH
Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
Page 32
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
Page 35
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad
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Page 42
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Chapter 10. When beans go bad
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Chapter 10. When beans go bad Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 11. Protect Your Secrets
Table of Contents Chapter 11. Protect Your Secrets.................................................................. 1 Section 11.1. OBJECTIVES.............................................................................................................................................................. 2 Section 11.2. Imagine you're writing a payroll application............................................................................................................ 3 Section 11.3. What can you do?....................................................................................................................................................... 4 Section 11.4. How to do security in EJB......................................................................................................................................... 5 Section 11.5. The Application Assembler's job: access control...................................................................................................... 6 Section 11.6. there are no Dumb Questions.................................................................................................................................... 7 Section 11.7. Sharpen your pencil................................................................................................................................................... 7 Section 11.8. Defining the roles....................................................................................................................................................... 8 Section 11.9. Defining the roles... a better way............................................................................................................................... 9 Section 11.10. Defining the method permissions.......................................................................................................................... 10 Section 11.11. Defining the method permissions........................................................................................................................... 11 Section 11.12. Method permissions interact with one another as a union !................................................................................. 12 Section 11.13. Watch out for ................................................................................................................................. 13 Section 11.14. The Deployer's job: mapping actual humans to abstract roles.............................................................................. 15 Section 11.15. Principals and Roles, Users and Groups................................................................................................................ 16 Section 11.16. Class-level vs. instance-level security.................................................................................................................... 18 Section 11.17. Using programmatic security to custom-tailor a method...................................................................................... 19 Section 11.18. The problem with isCallerInRole()........................................................................................................................ 20 Section 11.19. Map declarative security roles to the programmer's hard-coded (fake) roles...................................................... 21 Section 11.20. The complete security mapping picture................................................................................................................ 22 Section 11.21. Use security identity to pretend someone else is calling...................................................................... 23 Section 11.22. Security context propagation with ........................................................................................................ 24 Section 11.23. COFFEE CRAM...................................................................................................................................................... 25 Section 11.24. COFFEE CRAM..................................................................................................................................................... 28
Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 11. Protect Your Secrets
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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0HWKRGSHUPLVVLRQVLQWHUDFW ZLWKRQHDQRWKHUDVDXQLRQ -ETHOD PERMISSIONS DO NOT RELATE TO ONE ANOTHER IN THE SAME WAY THAT TRANSACTION ATTRIBUTES DO 7ITH TRANSACTION ATTRIBUTES USING A WILDCARD SAYS h%VERY METHOD IN THIS BEAN WILL HAVE THIS ATTRIBUTE UNLESS ) SAY OTHERWISE BY NAMING A SPECIlC METHOD IN A DIFFERENT CONTAINER TRANSACTION TAGv )N OTHER WORDS NAMING A SPECIlC METHOD OVERRIDES THE WILDCARD SETTING "UT WITH METHOD PERMISSIONS USING THE WILDCARD SAYS h!LL METHODS IN THIS BEAN CAN BE ACCESSED BY THIS ROLEv .OTHING ELSE YOU DO IN ANY OTHER METHOD PERMISSION WILL CHANGE THAT
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 16
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8ZQVKQXIT[IVL:WTM[=[MZ[IVL/ZW]X[ $AN *OHNSSON AUTHENTICATES TO THE SYSTEM USING HIS LOGIN NAME AND PASSWORD AND IS NOW REPRESENTED BY AN INSTANCE OF TYPE 0RINCIPAL )N A VENDOR SPECIlC WAY THE $EPLOYER HAS TOLD THE %*" APPLICATION THAT $ANS 0RINCIPAL IS ASSOCIATED WITH ONE OR MORE ROLES 3O WHENEVER $AN AS THE CLIENT CALLS A METHOD ON ONE OF THE BEANS CLIENT INTERFACES HIS 0RINCIPAL AND THE ROLES TO WHICH THAT 0RINCIPAL HAS BEEN ASSIGNED PROPAGATES WITH THE CALL 4HAT MEANS EVERY CALL ON THE CONCEPTUAL CALL STACK WILL SEE $ANS 0RINCIPAL AS THE CALLER
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 11. Protect Your Secrets
Page 18
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SURJUDPPDWLFVHFXULW\
+TI[[TM^MT^[QV[\IVKMTM^MT[MK]ZQ\a ?PMVLMKTIZI\Q^M[MK]ZQ\aQ[VW\MVW]OPaW]UQOP\VMMLXZWOZIUUI\QK [MK]ZQ\a\WZM[\ZQK\IKKM[[\WI[XMKQNQKQV[\IVKMWNIJMIV 3O FAR ALL THE SECURITY WEVE LOOKED AT HAS BEEN DECLARATIVENOT HARD CODED INTO THE BEAN CLASS $ECLARATIVE SECURITY IS COOL BECAUSE IT SUPPORTS THE WHOLE IDEA OF COMPONENT BASED DEVELOPMENTYOU CAN CUSTOMIZE THE BEAN AT DEPLOY TIME WITHOUT TOUCHING THE CODE #OMPANY ! MIGHT BE USING A BEAN IN ONE APPLICATION AND NEED A PARTICULAR TYPE OF ACCESS CONTROL THATS COMPLETELY DIFFERENT FROM THE WAY #OMPANY " IS USING THAT SAME BEAN /R EVEN TWO USES OF THE SAME BEAN IN THE SAME COMPANY MIGHT NEED DIFFERENT ACCESS CONTROL "UT DECLARATIVE SECURITY IS AT THE CLASS LEVEL 9OU SPECIFY WHICH METHODS A PARTICULAR ROLE CAN CALL BUT IT MEANS THAT ROLE CAN CALL THE METHOD ON !.9 INSTANCE OF THE BEAN CLASS )F YOU NEED INSTANCE LEVEL SECURITY YOU CANT DO IT IN THE DEPLOYMENT DESCRIPTOR "UT YOU CAN DO PROGRAMMATIC SECURITY WHICH OF COURSE YOU ALREADY KNOW YOUVE SEEN THE TWO SECURITY RELATED METHODS IN 3ESSION#ONTEXT AND %NTITY#ONTEXT 6RWKHUH,6 VRPHWKLQJ,FDQSXW LQP\EHDQFRGH
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"UT BE CAREFUL 4HERE IS NO GUARANTEE THAT THE NAME COMING FROM THE GET.AME METHOD ON THE PRINCIPAL MATCHES THE USERS LOG IN NAME 3O YOU HAVE TO ASSUME THAT AS SOON AS YOU PUT PROGRAMMATIC SECURITY INTO YOUR BEAN YOURE DRASTICALLY REDUCING ITS REUSABILITY AND PORTABILITY !ND IT MEANS THE "EAN 0ROVIDER MIGHT NEED TO BE MORE TIGHTLY COUPLED TO THE OPERATIONAL ENVIRONMENT THAN YOUD NORMALLY WANT "ECAUSE THE "EAN 0ROVIDER IS MAKING AN ASSUMPTION THAT THE NAME COMING FROM THE GET.AME METHOD WILL MATCH A PERSISTENT lELD IN THE ENTITY BEAN AND THAT MIGHT NOT BE TRUE IN ALL ENVIRONMENTS DEPENDING ON HOW YOUR SYSTEM HANDLES SECURITY
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 11. Protect Your Secrets
Page 19
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=[QVOXZWOZIUUI\QK[MK]ZQ\a\W K][\WU\IQTWZIUM\PWL 7E JUST LOOKED AT GET#ALLER0RINCIPAL TO SEE HOW YOU COULD lND OUT EXACTLY 7(/ THE CONTAINER BELIEVES IS CALLING THE METHOD "UT WE CAN ALSO USE THE IS#ALLER)N2OLE METHOD TO TEST WHETHER THE PRINCIPAL WHOEVER IT IS AND IN THIS CASE WE DONT CARE IS A MEMBER OF A SPECIlC ROLE THAT WE DO CARE ABOUT )MAGINE THAT YOU HAVE A PRIVATE PRICING METHOD CALLED BY ONE OF YOUR BUSINESS METHODS THAT CHECKS TO SEE IF THIS CUSTOMER AUTHENTICATED AS A MEMBER OF YOUR SPECIAL 6)0 CUSTOMER GROUP )F HE IS YOU TREAT HIM DIFFERENTLY THAN IF HE ISNT -AYBE YOU GIVE HIM A DISCOUNT -AYBE YOU RAISE THE PRICE 7HATEVER YOUR BUSINESS LOGIC TELLS YOU TO DO SULYDWHYRLGGHWHUPLQH3ULFH ^ LI FRQWH[WLV&DOOHU,Q5ROH ³9,3&XVWRPHU´ ^ WUHDWFXVWRPHUZHOO `HOVH^ WUHDWKLPOLNHWKHORVHUKHLV ` ` "ESIDES THE OBVIOUS PROBLEM WITH HARD CODING SECURITY INFORMATION CUTS DOWN YOUR REUSE INCREASES THE CHANCES THAT THINGS WONT WORK IN A PORTABLE WAY ETC THERES ANOTHER BIG PROBLEMHOW THE HECK DOES THE "EAN 0ROVIDER KNOW IN ADVANCE WHAT ROLES THE !PP !SSEMBLER IS GOING TO ASSIGN (E DOESNT /R AT LEAST HE PROBABLY SHOULDNT 7E KNOW WE KNOW )N REALITY THE "EAN 0ROVIDER AND !PP !SSEMBLER ARE IF NOT THE SAME PERSON CLOSELY RELATED PROFESSIONALLY SPEAKING OF COURSE "UT WERE STILL PUSHING FOR A COMPONENT BASED DEVELOPMENT MODEL HERE AND AT THE VERY LEAST WE WANT THE !PP !SSEMBLER TO TAKE WHAT THE "EAN 0ROVIDER HAS DONE AND SOMEHOW lT IT INTO HER OWN APPLICATION !ND THAT MIGHT MEAN INTEGRATING THE BEAN WITH BEANS FROM OTHER PROVIDERS
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3O NOW IMAGINE THIS SCENARIO !NNIE THE !PP !SSEMBLER IS BUILDING A NEW APP FROM FOUR EXISTING BEANS TWO OF WHICH CAME FROM DIFFERENT PROVIDERS 0ROVIDERS WHO DIDNT WORK FOR THE SAME COMPANY OR KNOW ONE ANOTHER (OW COULD THEY HAVE COMMUNICATED IN ADVANCE TO KNOW WHICH ROLES !NNIE WAS GOING TO CHOOSE FOR HER APPLICATION \RXDUHKHUH
Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 22
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 23
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=[M$Z]VI[&[MK]ZQ\aQLMV\Q\a\W XZM\MVL[WUMWVMMT[MQ[KITTQVO 7HEN A CLIENT CALLS A METHOD THE #ONTAINER ALWAYS KNOWS THE CLIENTS 0RINCIPAL WHICH INCLUDES THE ABSTRACT SECURITY ROLES THE $EPLOYER ASSIGNED TO THAT 0RINCIPAL !ND REMEMBER THE CALLERS SECURITY CONTEXT IS PROPAGATED THROUGHOUT THE APPLICATION AS THE CLIENTS ORIGINAL METHOD GOES ABOUT DOING ITS WORK %ACH METHOD CALLED IN THE CONCEPTUAL CALL STACK WILL GET THE SECURITY CONTEXT ALONG WITH THE CALL
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"UT LETS SAY THAT YOU DONT WANT THE CLIENTS SECURITY CONTEXT TO KEEP PROPAGATING ,ETS SAY THAT WHEN THE CLIENT CALLS "EAN ! AND "EAN ! IN TURN CALLS "EAN " YOU WANT "EAN " TO THINK THAT SOMEONE ELSE IS CALLING )N OTHER WORDS WHAT IF YOU WANT "EAN ! TO PRETEND TO BE SOMEONE ELSE 4HAT WAY ANY BEAN THAT "EAN ! CALLS WILL THINK THE 0RINCIPAL AND ROLES OF THE CALLER IS SOMETHING OTHER THAN THE ORIGINAL CLIENTS 7HY WOULD YOU DO THIS "EAN " MIGHT HAVE TIGHTER ACCESS CONTROL 0ERHAPS "EAN " WONT ALLOW OUTSIDE CLIENTS TO CALL ITS METHODS SO IT DOESNT HAVE METHOD PERMISSIONS SET UP FOR ANY OF THE ABSTRACT ROLES MAPPED TO CLIENTS USERS AND GROUPS "UT PERHAPS YOU HAVE A SPECIAL ROLE SET UP JUST FOR OTHER BEANS AND "EAN " WILL TAKE CALLS FROM OTHER BEANS AS LONG AS THOSE BEANS ARE IN THAT ROLE :KHQ\RXZDQWWKHEHDQWR%(VRPH RQHRWKHUWKDQWKHFDOOLQJFOLHQW
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 11. Protect Your Secrets Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 12. The Joy of Deployment
Table of Contents Chapter 12. The Joy of Deployment.............................................................. 1 Section 12.1. OBJECTIVES............................................................................................................................................................. 2 Section 12.2. A bean's special place- java:comp/env...................................................................................................................... 4 Section 12.3. But it's not per bean instance... It's per bean home.................................................................................................. 5 Section 12.4. Environment subcontexts......................................................................................................................................... 6 Section 12.5. brain power................................................................................................................................................................ 7 Section 12.6. It's simple.................................................................................................................................................................. 8 Section 12.7. Environment entries: deploy-time constants........................................................................................................... 9 Section 12.8. there are no Dumb Questions................................................................................................................................. 10 Section 12.9. It's subcontexts all the way down............................................................................................................................. 11 Section 12.10. Resource manager connection factories (think: database)................................................................................... 12 Section 12.11. The complete resource mapping picture................................................................................................................ 14 Section 12.12. EJB references (when a bean wants another bean)............................................................................................... 15 Section 12.13. there are no Dumb Questions................................................................................................................................ 16 Section 12.14. Using with EJB references................................................................................................................... 17 Section 12.15. Resource environment references (think: JMS destinations).............................................................................. 18 Section 12.16. Bean Provider and Application Assembler............................................................................................................ 19 Section 12.17. Deployer responsibility for the Deployment Descriptor....................................................................................... 20 Section 12.18. Remembering who does what................................................................................................................................ 21 Section 12.19. Now let's look at the bean's runtime environment............................................................................................... 22 Section 12.20. Which APIs does EJB 2.0 guarantee?.................................................................................................................. 23 Section 12.21. Sharpen your pencil............................................................................................................................................... 23 Section 12.22. What MUST be in an ejb-jar?................................................................................................................................ 26 Section 12.23. Programming restrictions..................................................................................................................................... 27 Section 12.24. ExeRciSe: Memorize THIS.................................................................................................................................... 28 Section 12.25. COFFEE CRAM..................................................................................................................................................... 29 Section 12.26. COFFEE CRAM..................................................................................................................................................... 34
Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 12. The Joy of Deployment
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 12. The Joy of Deployment
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(QYLURQPHQWHQWULHV GHSOR\WLPHFRQVWDQWV )MAGINE YOURE WRITING A SIMPLE CHECKOUT BEAN FOR AN ONLINE SHOPPING CART SYSTEM 9OU DONT KNOW WHERE THAT BEAN MIGHT END UP %VEN IF YOU DO YOU KNOW THAT THINGS LIKE TAX RATES AND DISCOUNT POLICIES CAN CHANGE EVEN WITHIN THE SAME COMPANY %NVIRONMENT ENTRIES LET YOU WRITE YOUR CODE USING A VARIABLE THAT YOULL l LL IN AT RUNTIME USING A *.$) LOOKUP 2EMEMBER THE "EAN 0ROVIDER CHOOSES THE NAME AND ITS UP TO THE $EPLOYER TO l LL IN THE VALUE LQDEHDQ·VEXVLQHVVPHWKRG
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 12. The Joy of Deployment
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 11
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,W·VVXEFRQWH[WVDOOWKHZD\GRZQ 2EMEMBER YOUR JAVACOMPENV SPACE IS JUST A SUBCONTEXT ! SPECIAL ONE SURE BUT STILL A CONTEXT 3O YOU CAN SAVE THAT IN A #ONTEXT VARIABLE AND SAVE YOURSELF FROM HAVING TO RETYPE hJAVACOMPENVv EVERY FRICKIN TIME YOU WANT TO LOOK SOMETHING UP 6DYLQJ\RXUVSHFLDOHQYLURQPHQWFRQWH[W ,QLWLDO&RQWH[WLF QHZ,QLWLDO&RQWH[W &RQWH[WP\6SHFLDO3ODFH &RQWH[W LFORRNXS ³MDYD FRPSHQY´ QRZORRNVRPHWKLQJXSRQP\6SHFLDO3ODFH 'RXEOHGEO 'RXEOH P\6SHFLDO3ODFHORRNXS ³VPDUW&XVWRPHU'LVFRXQW´
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 12
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 13
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 14
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 15
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(-%UHIHUHQFHV ZKHQDEHDQZDQWVDQRWKHUEHDQ "EANS WHO NEED OTHER BEANS ARE THE LUCKIEST BEANS IN THE SERVER "UT REMEMBER BEANS HAVE TO GO THROUGH THE HOME INTERFACE JUST LIKE EVERYBODY ELSE )F "EAN ! WANTS TO DO A *.$) LOOKUP ON "EAN "S HOME WEVE GOT THE SAME PROBLEM AS ALWAYSWHATS "EAN "S *.$) NAME !S A "EAN 0ROVIDER YOURE JUST MAKING ONE UP !T DEPLOY TIME THE $EPLOYER WILL MAP YOUR FAKE CODED NAME TO THE REAL *.$) NAME MATCHING A BEAN OF THE TYPE YOU SPECIlED IN THE $$
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 16
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) UNDERSTAND THE ELEMENT NAMES FOR HOME AND LOCAL HOME -AKES SENSE "UT WHATS UP WITH REMOTE AND LOCAL 3HOULDNT IT BE COMPONENT AND LOCAL COMPONENT
A:
9OU CAN RUN FROM YOUR PAST BUT YOU CANT HIDE "EFORE %*" THERE WAS NO CONCEPT OF LOCAL INTERFACES 3O THE CLIENT VIEW WAS ALWAYS CALLED (OME AND 2EMOTE !LTHOUGH EVEN THAT WAS AN INCONSISTENT NAME SCHEME SINCE BOTH THE HOME AND THE BUSINESS METHOD INTERFACE WERE 2EMOTE AS IN JAVARMI2EMOTE "UT ONCE LOCAL INTERFACES CAME ON THE SCENE THINGS GOT A BIT MORE COMPLICATED h,ETS SEE WE CAN NAME THE LOCAL HOME hLOCAL HOMEv AND THEN WELL NAME THE LOCAL REMOTE hLOCAL REMOTEv 3EE THE PROBLEM 3O WITH %*" WE STOPPED CALLING THE BUSINESS INTERFACE hTHE REMOTE INTERFACEv AND STARTED CALLING IT hTHE COMPONENT INTERFACEv !ND NOW WE CALL THEM hLOCAL COMPONENT INTERFACESv AND hREMOTE COMPONENT INTERFACESv
Q:
5M YOU STILL DIDNT ANSWER MY QUESTION (OW COME THE TAG STILL SAYS hREMOTEv FOR THE REMOTE COMPONENT INTERFACE AND hLOCALv FOR THE LOCAL COMPONENT INTERFACE
A:
"ECAUSE OF THE PAST "ACKWARD COMPATIBILITY AND ALL THAT )N %*" THE EJB REF TAGS SAID HOME AND REMOTE SO THEY STILL DO 4HE NAMING SCHEME IS BASICALLY THIS h4HE COMPONENT INTERFACE IS EITHER LOCAL OR REMOTE )F THE TAG DOESNT EXPLICITLY SAY hHOMEv THEN YOURE TALKING ABOUT THE COMPONENT INTERFACE 4HESE QUIRKY LITTLE INCONSISTENCIES ARE JUST PART OF %*"S CHARM
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Chapter 12. The Joy of Deployment
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Page 26
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Chapter 12. The Joy of Deployment
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Page 27
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Chapter 12. The Joy of Deployment
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Page 28
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Page 29
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Page 30
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 31
DEHDQ¶VHQYLURQPHQW
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Page 32
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FRIIHHFUDPPRFNH[DP
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 33
DEHDQ¶VHQYLURQPHQW
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Page 34
PRFNH[DPDQVZHUV
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 12. The Joy of Deployment
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Page 35
DEHDQ¶VHQYLURQPHQW
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 12. The Joy of Deployment
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Page 36
PRFNH[DPDQVZHUV
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 12. The Joy of Deployment
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Page 37
DEHDQ¶VHQYLURQPHQW
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7HO WILL TYPICALLY MERGE MULTIPLE EJB JAR lLES INTO A SINGLE EJB JAR lLE
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Chapter 12. The Joy of Deployment
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Page 38
PRFNH[DPDQVZHUV
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15
7HICH ROLE IS TYPICALLY RESPONSIBLE FOR DECLARING THE RESOURCE CONNECTION FACTORY REFERENCES IN THE DEPLOYMENT DESCRIPTOR
(spec: 423)
R! BEAN PROVIDER R" APPLICATION ASSEMBLER R# DEPLOYER R$ CONTAINER PROVIDER R% SYSTEM ADMINISTRATOR
16
7HATS TRUE ABOUT A LEGAL EJB JAR lLE #HOOSE ALL THAT APPLY
17
7HICH ROLE WOULD TYPICALLY SET UP RESOURCE MANAGER SIGN ON INFORMATION
(spec: 488)
R! )T MUST CONTAIN BOTH A HOME INTERFACE AND A COMPONENT INTERFACE R" 4HE DEPLOYMENT DESCRIPTOR IS OPTIONAL R# )T MUST CONTAIN ANY *%% CLASSES USED BY THE BEAN R$ 4HE ENTERPRISE BEAN CLASS IS OPTIONAL
(spec: 422)
R! BEAN PROVIDER R" APPLICATION ASSEMBLER R# DEPLOYER R$ CONTAINER PROVIDER R% SYSTEM ADMINISTRATOR
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Chapter 12. The Joy of Deployment Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Appendix A. Final Mock Exam
Table of Contents Appendix A. Final Mock Exam..................................................................... 1 Section A.1. COFFEE CRAM........................................................................................................................................................... 1 Section A.2. COFFEE CRAM.......................................................................................................................................................... 2 Section A.3. COFFEE CRAM: Master Mock Exam Answers........................................................................................................ 24 Section A.4. This isn't goodbye..................................................................................................................................................... 46 Section A.5. Cover Rough Drafts for the series............................................................................................................................. 47
Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 1
Appendix A:
Final Mock Exam
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 2
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7HICH ARE BENElTS OF %*" #HOOSE ALL THAT APPLY
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7HICH METHODS ARE DIRECTLY INVOKED BY THE CLIENT #HOOSE ALL THAT APPLY
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7HICH METHODS CAN BE FOUND IN THE %*"(OME INTERFACE #HOOSE ALL THAT APPLY
R! HME3DVVLYDWH R" BUSINESS METHODS R# VHW6HVVLRQ&RQWH[W R$ QHZ,QVWDQFH R% FUHDWH
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 3
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7HICH METHODS CAN BE RUN BY A #-0 BEAN IN THE POOLED STATE #HOOSE ALL THAT APPLY
R! HME/RDG R" HME)LQG R# HME6WRUH R$ HME&UHDWH R% "USINESS METHOD R& HME+RPH
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7HATS TRUE ABOUT MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
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R# 4HE BEANS HME&UHDWH METHOD MUST TAKE A SINGLE ARGUMENT OF TYPE MDYD[MPV0HVVDJH
R$ 4HE BEAN PROVIDER USES THE DEPLOYMENT DESCRIPTOR TO INDICATE WHETHER INSTANCES OF THE BEAN CLASS ARE INTENDED FOR TOPICS OR QUEUES
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7HATS TRUE ABOUT AN ENTERPRISE BEANS ENVIRONMENT #HOOSE ALL THAT APPLY
R! "EFORE A BEAN CAN ACCESS ITS ENVIRONMENT ENTRIES THE BEAN MUST lRST OBTAIN THE NAMING CONTEXT USING A 6HVVLRQ&RQWH[W OBJECT
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7HATS TRUE ABOUT SECURITY ROLES IN %*"S #HOOSE ALL THAT APPLY
R! 3ECURITY ROLES ARE DElNED IN THE DEPLOYMENT DESCRIPTOR USING SECURITY ROLE ELEMENTS
R" 3ECURITY ROLES ARE SCOPED TO THE INSTANCE LEVEL R# -ANY METHODS CAN BE MAPPED TO A SINGLE SECURITY ROLE R$ ! METHOD CAN APPEAR IN ONLY ONE SECURITY ROLE
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Appendix A. Final Mock Exam
Page 4
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!N %*" CONTAINER MUST SUPPORT AT LEAST A SUBSET OF WHICH !0)S #HOOSE ALL THAT APPLY
R! *4! R" *$"# R# *-3 R$ *!8 2#0
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7HICH STATEMENTS CONCERNING STATELESS SESSION BEANS ARE TRUE #HOOSE ALL THAT APPLY
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10
7HAT CAPABILITY EXISTS IN /.,9 /.% OF THE TWO BUT NOT BOTH AN ENTITY OBJECTS REMOTE COMPONENT INTERFACE AN ENTITY OBJECTS LOCAL COMPONENT INTERFACE #HOOSE ALL THAT APPLY
R! 2EMOVING THE OBJECT R" /BTAINING THE OBJECTS HANDLE R# )NVOKING BUSINESS METHODS R$ /BTAINING THE OBJECTS PRIMARY KEY
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7HEN CREATING A #-0 ENTITY BEAN WHICH METHODS ARE OPTIONAL #HOOSE ALL THAT APPLY
R! HME/RDG R" HME&UHDWH R# HME5HPRYH R$ HME6HOHFW R% HME3DVVLYDWH R& VHW(QWLW\&RQWH[W
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 5
DSSHQGL[$ILQDOPRFNH[DP
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7HICH METHODS CAN BE CALLED ON A BEAN IN THE POOLED STATE #HOOSE ALL THAT APPLY
R! HME)LQG R" HME/RDG R# HME6WRUH R$ HME6HOHFW R% HME3DVVLYDWH
13
7HATS TRUE ABOUT THE LIFECYCLE OF A MESSAGE DRIVEN BEAN #HOOSE ALL THAT AP PLY
R! 7HEN THE THE OQ0HVVDJH METHOD COMPLETES THE CONTAINER WILL TYPI CALLY CALL EJB2EMOVE
R" 4HE ON0HVVDJH METHOD CAN THROW APPLICATION EXCEPTIONS R# -ESSAGE DRIVEN BEANS CAN RUN ONLY WITH #-4 DEMARCATION R$ 4HE JHW5ROOEDFN2QO\ METHOD CAN BE CALLED ONLY FROM THE ON-ESSAGE METHOD
14
7HICH STATEMENTS CONCERNING MESSAGE DRIVEN BEAN CLASSES ARE TRUE #HOOSE ALL THAT APPLY
R! 4HEY MUST IMPLEMENT DIRECTLY OR INDIRECTLY MDYD[MPV0HVVDJH R" 4HEY MUST HAVE A PUBLIC CONSTRUCTOR THAT TAKES A SINGLE ARGUMENT OF TYPE MDYD[MPV0HVVDJH
R# )MPLEMENTING THE ¿QDOL]H METHOD IS ALLOWED R$ )MPLEMENTING THE HME&UHDWH METHOD IS OPTIONAL R% 4HE CLASS MUST NOT BE DECLARED @lNAL
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7ITHIN THE DEPLOYMENT DESCRIPTORS HMEORFDOUHI! ELEMENT WHICH ELE MENTS ARE OPTIONAL #HOOSE ALL THAT APPLY
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
Appendix A. Final Mock Exam
Page 6
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FRIIHHFUDPPRFNH[DP
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7HATS TRUE ABOUT RESOURCE MANAGER CONNECTION FACTORIES #HOOSE ALL THAT APPLY
R4HE UHVVKDULQJVFRSH! DEPLOYMENT DESCRIPTOR ELEMENT IS USED TO INDICATE WHETHER CONNECTIONS TO A RESOURCE MANAGER ARE SHAREABLE ACROSS MULTIPLE %*"S IN AN APPLICATION
R" 4HE UHVVKDULQJVFRSH! DEPLOYMENT DESCRIPTOR ELEMENT CONTAINS THE UHVRXUFHUHI! ELEMENT
R# !LL OF A BEANS RESOURCE MANAGER CONNECTION FACTORY REFERENCES ARE DECLARED IN A SINGLE UHVRXUFHUHI! ELEMENT USING UHVUHIQDPH! ELEMENTS TO DISTINGUISH THEM
R$ "Y DEFAULT CONNECTIONS TO A GIVEN RESOURCE MANAGER ARE SHAREABLE ACROSS MULTIPLE BEANS IN AN APPLICATION
17
7HATS TRUE ABOUT SECURITY ROLES REFERENCED FROM AN %*"S CODE #HOOSE ALL THAT APPLY
R! )N THE DEPLOYMENT DESCRIPTOR SUCH REFERENCES ARE CONTAINED IN THE VHFXULW\UROHUHI! ELEMENT
R" 4HE VHFXULW\UROH! ELEMENT INCLUDES THE VHFXULW\UROH UHI! ELEMENT
R# 7ITHIN THE VHFXULW\UROHUHI! ELEMENT THE UROHQDPH! ELEMENTS VALUE IS THE SAME AS THE ARGUMENT FOR THE BEANS INVOCATION OF THE LV&DOOHU,Q5ROH METHOD
R$ 4HE UROHOLQN! ELEMENT IS USED TO LINK TWO VHFXULW\UROHUHI! ELEMENTS
18
7HATS TRUE ABOUT THE CLIENTS VIEW OF SECURITY #HOOSE ALL THAT APPLY
R! ! TRANSACTIONAL CLIENT CANNOT CHANGE ITS PRINCIPAL ASSOCIATION WITHIN A TRANSACTION
R" ! SESSION BEANS CLIENT CANNOT CHANGE ITS PRINCIPAL ASSOCIATION FOR THE DURATION OF THE COMMUNICATION WITH THE SESSION OBJECT
R# 4RANSACTIONAL REQUESTS WITHIN A SINGLE TRANSACTION CANNOT ARRIVE FROM MULTIPLE CLIENTS
R$ .ONE OF THE ABOVE
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 7
DSSHQGL[$ILQDOPRFNH[DP
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7HEN PROGRAMMING AN ENTITY BEAN CLASS WHICH TECHNIQUES SHOULD BE !6/)$%$ TO ENSURE BEAN PORTABILITY ACROSS ALL %*" CONTAINERS #HOOSE ALL THAT APPLY
R! #HANGING A THREADS PRIORITY R" 5SING THE REmECTION !0) R# 5SING WRAPPER CLASSES R$ 5SING STATIC NESTED CLASSES
20
7HEN PROGRAMMING A MESSAGE DRIVEN BEAN CLASS WHICH TECHNIQUES SHOULD BE AVOIDED TO ENSURE BEAN PORTABILITY ACROSS ALL %*" CONTAINERS #HOOSE ALL THAT APPLY
R! 5SING 3WING !0)S FOR A '5) R" 5SING THE @TRANSIENT MODIlER R# 5SING NATIVE LIBRARIES R$ 2EADING lLE DESCRIPTORS
21
7HAT IS REQUIRED OF THE CONTAINER WHEN IT PASSIVATES A STATEFUL SESSION BEAN
R! 4HE BEANS INSTANCE STATE WILL ALWAYS UNDERGO *AVA PROGRAMMING LAN GUAGE 3ERIALIZATION
R" )T MUST SAVE ALL OF THE BEANS INSTANCE lELD STATE REGARDLESS OF THE lELDS MODIlERS
R# )T MUST SAVE ANY REFERENCES TO THE BEANS 3ESSION#ONTEXT OBJECT R$ )T MUST SAVE ALL NON NULL TRANSIENT VARIABLES
22
7HICH CAPABILITIES ARE DElNED IN THE MDYD[HME(-%/RFDO2EMHFW INTER FACE #HOOSE ALL THAT APPLY
R! 2EMOVE AN ENTITY OBJECT R" /BTAIN AN ENTITY OBJECTS PRIMARY KEY R# /BTAIN A LOCAL HOME INTERFACE FOR THE ENTITY OBJECT R$ /BTAIN A REMOTE COMPONENT INTERFACE FOR THE ENTITY OBJECT R% %XPOSE THE METHODS OF THE MDYD[HME(QWLW\%HDQ INTERFACE TO THE CLIENT
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 8
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7HATS TRUE ABOUT EJB3ELECT METHODS #HOOSE ALL THAT APPLY
R! 4HEY CAN BE EXPOSED TO THE CLIENT R" 4HEY CAN RETURN ONLY %*"/BJECTS OR %*",OCAL/BJECTS R# 4HEY CAN BE INVOKED ONLY BY A BEAN IN THE READY STATE R$ 4HEY MUST BE ASSOCIATED WITH A QUERY ELEMENT IN THE DEPLOYMENT DE SCRIPTOR
24
7HICH METHODS CAN .%6%2 BE SUCCESSFULLY INVOKED FROM A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
R! LV&DOOHU,Q5ROH R" JHW(-%+RPH R# JHW5ROOEDFN2QO\ R$ VHW5ROOEDFN2QO\ R% JHW&DOOHU3ULQFLSDO
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7HICH ROLE IS TYPICALLY RESPONSIBLE FOR ADDING EJB LINK ELEMENTS TO AN %*"S DEPLOYMENT DESCRIPTOR
R! BEAN PROVIDER R" APPLICATION ASSEMBLER R# DEPLOYER R$ CONTAINER PROVIDER R% SYSTEM ADMINISTRATOR
26
)N WHICH OF THE FOLLOWING METHODS CAN A STATELESS SESSION BEAN INVOKE THE LV&DOOHU,Q5ROH METHOD IN ORDER TO PERFORM A SECURITY CHECK #HOOSE ALL THAT APPLY
R! HME&UHDWH R" HME5HPRYH R# VHW6HVVLRQ&RQWH[W R$ .ONE OF THE ABOVE
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 9
DSSHQGL[$ILQDOPRFNH[DP
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7HICH TWO ARE TYPICALLY RESPONSIBLE FOR CREATING EJB JAR lLES #HOOSE TWO
28
7HICH OF THE FOLLOWING STATELESS SESSION BEAN CONTAINER CALLBACK METHODS TAKES AN ARGUMENT #HOOSE ALL THAT APPLY
R! 4HE BEAN PROVIDER R" 4HE APPLICATION ASSEMBLER R# 4HE DEPLOYER R$ 4HE SYSTEM ADMINISTRATOR
R! HME5HPRYH R" HME&UHDWH R# HME&UHDWH R$ HME3DVVLYDWH R% VHW6HVVLRQ&RQWH[W
29
7HICH OF THESE CAN NEVER BE CALLED ON A 3ESSION#ONTEXT INTERFACE #HOOSE ALL THAT APPLY
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7HATS TRUE ABOUT AN ENTITY BEANS REMOTE COMPONENT INTERFACE #HOOSE ALL THAT APPLY
R! )F A CLIENT ATTEMPTS TO INVOKE A METHOD ON AN ENTITY THAT DOES NOT EXIST A MDYDUPL1R6XFK5HPRWH2EMHFW([FHSWLRQ WILL BE THROWN
R" )T MUST EXTEND MDYD[HME(-%+RPH R# )TS METHODS MUST DECLAREMDYDUPL5HPRWH([FHSWLRQ R$ )T DElNES AUHPRYH +DQGOHKDQGOH METHOD
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 10
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7HICH ARE TRUE ABOUT lNDER METHODS IN AN ENTITY BEANS LOCAL HOME INTERFACE #HOOSE ALL THAT APPLY
R! 4HEY CAN HAVE ANY LEGAL *AVA NAME R" 4HEY MUST ALL DECLARE MDYD[HME)LQGHU([FHSWLRQ R# 4HEY CAN OPTIONALLY DECLARE MDYDUPL5HPRWH([FHSWLRQ R$ 4HE ¿QG%\3ULPDU\.H\ METHOD CAN BE OVERLOADED R% 4HE ¿QG%\3ULPDU\.H\ METHODS RETURN TYPE MUST BE THE BEANS LOCAL COMPONENT INTERFACE
R& ! METHOD CALLED hlND888v MUST HAVE THE BEANS LOCAL COMPONENT INTERFACE AS ITS DECLARED RETURN TYPE
32
7HICH ARE TRUE FOR A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
R! 4HE $EPLOYER USES THE DEPLOYMENT DESCRIPTOR TO DETERMINE WHETHER A BEAN IS INTENDED FOR A 1UEUE OR A 4OPIC
R" 4HE CLASS MUST BE DECLARED lNAL R# 4HE CLASS MUST DElNE ONE HME5HPRYH METHOD R$ 4HE CLASS CAN HAVE OVERLOADED HME&UHDWH METHODS R% 4HE CLASS MUST DElNE A NO ARGUMENT ON-ESSAGE METHOD
33
'IVEN THE FOLLOWING SUBSET OF A DEPLOYMENT DESCRIPTOR HQWLW\! HMEQDPH!3D\UROO HMEQDPH! VHFXULW\UROHUHI! UROHQDPH!FOHUN UROHQDPH! VHFXULW\UROHUHI! HQWLW\! 7HICH CODE SNIPPETS MAKES A LEGAL SECURITY CHECK #HOOSE ALL THAT APPLY
R! FRQWH[WLV&DOOHU,Q5ROH ³3D\UROO´ R" FRQWH[WLV&DOOHU,Q5ROH ³FOHUN´ R# FRQWH[WLV&DOOHU,Q5ROH ³3D\UROOFOHUN´ R$ FRQWH[WLV&DOOHU,Q5ROH ³3D\UROOFOHUN´
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 11
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7HICH ARE VALID LOCAL HOME INTERFACES FOR A STATEFUL SESSION BEAN #HOOSE ALL THAT APPLY
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R% SXEOLFLQWHUIDFH7HVW%HDQH[WHQGV MDYD[HME(-%/RFDO+RPH^ 7 HVW%HDQ/RFDOFUHDWH WKURZV/RFDO([FHSWLRQ `
35
7HICH METHODS CAN BE CALLED BY A BEAN PROVIDER #HOOSE ALL THAT APPLY
R! UHPRYH R" HME&UHDWH R# DIWHU%HJLQ R$ JHW&DOOHU3ULQFLSDO R% HME3DVVLYDWH
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HO WILL TYPICALLY SPECIFY WHETHER A BEAN IS RE ENTRANT IN THE BEANS DEPLOY MENT DESCRIPTOR
R! 4HE BEAN PROVIDER R" 4HE APPLICATION ASSEMBLER R# 4HE DEPLOYER R$ 4HE SYSTEM ADMINISTRATOR
37
7HICH STATEMENTS ABOUT STATEFUL AND STATELESS SESSION BEANS ARE TRUE #HOOSE ALL THAT APPLY
R! /NLY STATEFUL SESSION BEANS SUPPORT TRANSACTIONS R" /NLY STATEFUL SESSION BEANS CAN BE PASSIVATED R# /NLY STATEFUL SESSION BEANS HAVE A µVHW6HVVLRQ&RQWH[W¶ METHOD R$ "OTH STATEFUL AND STATELESS SESSION BEANS CAN SUPPORT OVERLOADED µHME&UHDWH¶METHODS
R% "OTH STATEFUL AND STATELESS SESSION BEANS CAN IMPLEMENT THE MDYD[HME6HVVLRQ6\QFKURQL]DWLRQ INTERFACE
R& "OTH STATEFUL AND STATELESS SESSION BEANS CAN HAVE INSTANCE VARIABLE STATE
38
7HICH MUST BE INCLUDED IN EVERY EJB JAR lLE #HOOSE ALL THAT APPLY
39
7HICH METHODS ARE DECLARED IN THE JAVAXEJB%*"(OME INTERFACE #HOOSE ALL THAT APPLY
R! 4HE STUB FOR THE %*"(OME INTERFACE EITHER DIRECTLY OR BY REFERENCE R" 4HE *!2 -ANIFEST lLE R# ! DEPLOYMENT DESCRIPTOR R$ 4HE *.$) CONTEXT R% 4HE %*"S HOME INTERFACE EITHER DIRECTLY OR BY REFERENCE
R! FUHDWH R" ORRNXS R# JHW+DQGOH R$ JHW+RPH+DQGOH R% VHW6HVVLRQ&RQWH[W
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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DSSHQGL[$ILQDOPRFNH[DP
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(OW MANY JAVAXEJB%*",OCAL(OME INTERFACE METHODS CAN BE CALLED WITHOUT AN EXCEPTION FROM A SESSION BEAN CLIENT
R! R" R# R$ R%
41
7HICH OF THE FOLLOWING IF CALLED ALWAYS HAVE THE SAME TRANSACTION CONTEXT AS A SESSION BEANS BUSINESS METHODS #HOOSE ALL THAT APPLY
R! CONSTRUCTOR R" VHW6HVVLRQ&RQWH[W R# DIWHU%HJLQ R$ DIWHU&RPSOHWLRQ R% EHIRUH&RPSOHWLRQ
42
'IVEN A STATEFUL SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCATION FROM WHICH METHODS CAN YOU ACCESS ANOTHER BEAN #HOOSE ALL THAT APPLY
R! VHW6HVVLRQ&RQWH[W R" HME&UHDWH R# DIWHU%HJLQ R$ EHIRUH&RPSOHWLRQ R% DIWHU&RPSOHWLRQ
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7HICH DEPLOYMENT DESCRIPTOR ELEMENTS CAN OPTIONALLY SPECIFY CASCADE DELETE FUNCTIONALITY #HOOSE ALL THAT APPLY
R! HMEUHODWLRQ! R" DEVWUDFWVFKHPDQDPH! R# HMEUHODWLRQVKLSUROH! R$ UHODWLRQVKLSUROHVRXUFH!
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FRIIHHFUDPPRFNH[DP
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7HATS TRUE ABOUT CASCADE DELETE #HOOSE ALL THAT APPLY
R! )T IS DECLARED IN THE HME5HPRYH METHOD R" 7HEN A CASCADE DELETE ENABLED BEAN IS DELETED IT CAUSES ALL OF THE BEANS WITH RELATIONSHIPS TO IT TO BE AUTOMATICALLY DELETED TOO
R# )T CAN BE SPECIlED FOR ONE TO ONE ONE TO MANY OR MANY TO MANY RELA TIONSHIPS
R$ ! CASCADE DELETE ENABLED BEAN IS AUTOMATICALLY REMOVED WHEN ANY hMULTIPLICITY OF ONEv BEAN WITH WHICH IT IS RELATED IS REMOVED
45
7HICH METHODS FROM THE %NTITY#ONTEXT INTERFACE CAN BE INVOKED REGARDLESS OF TRANSACTION CONTEXT #HOOSE ALL THAT APPLY
R! JHW(-%+RPH R" JHW(-%2EMHFW R# VHW5ROOEDFN2QO\ R$ JHW5ROOEDFN2QO\
46
7HATS TRUE ABOUT AN ENTITY BEANS PRIMARY KEY #HOOSE ALL THAT APPLY
R! 0RIMARY KEY lELDS MUST BE CMP lELDS R" 3ETTER METHODS FOR lELDS ASSOCIATED WITH A PRIMARY KEY MUST NOT BE EXPOSED THROUGH A CLIENT VIEW
R# )F TWO ENTITY OBJECTS HAVE THE SAME HOME AND THE SAME PRIMARY KEY THEY ARE CONSIDERED IDENTICAL
R$ 4HE JHW3ULPDU\.H\ METHOD CAN BE INVOKED ON REFERENCES TO ONLY REMOTE HOME INTERFACES NOT LOCAL HOME INTERFACES
47
7HICH INTERFACES ARE USED BY THE BEAN PROVIDER TO PERFORM "-4 DEMARCA TION #HOOSE ALL THAT APPLY
R! MDYD[WUDQVDFWLRQ7UDQVDFWLRQ R" MDYD[WUDQVDFWLRQ8VHU7UDQVDFWLRQ R# MDYD[WUDQVDFWLRQ6\QFKURQL]DWLRQ R$ MDYD[WUDQVDFWLRQ7UDQVDFWLRQ0DQDJHU
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7HICH OF THE FOLLOWING ARE LEGAL %*" 1, QUERIES #HOOSE ALL THAT APPLY
R! 3%,%#4 C
&2/- #USTOMER C
R" 3%,%#4 /"*%#4 CNAME
&2/- #USTOMER C
R# 3%,%#4 /"*%#4 C
7(%2% #USTOMER C
R$ 3%,%#4 /"*%#4 C
&2/- #USTOMER C
R% 3%,%#4 CNAME
49
&2/- #USTOMER C
7HICH ARE TRUE ABOUT TRANSACTIONS IN %*" #HOOSE ALL THAT APPLY
R! /NLY ONE DATABASE CAN BE UPDATED WITHIN A SINGLE TRANSACTION R" %NTITY BEANS WITH "-4 DEMARCATION MUST USE THE SET3TATUS METHOD INSTEAD OF THE VHW5ROOEDFN2QO\ METHOD
R# %NTITY BEANS WITH "-4 DEMARCATION MUST USE THE GET3TATUS METHOD INSTEAD OF THE JHW5ROOEDFN2QO\ METHOD
R$ "-4 DEMARCATION SHOULD BE USED WHEN BEANS ACCESS RESOURCE MANAG ERS THAT DO NOT SUPPORT TRANSACTIONS
R% 4HE @3ESSION3YNCHRONIZATION INTERFACE CAN BE USED ONLY BY STATEFUL SESSION BEANS
50
4O ENSURE BEAN PORTABILITY WHICH TRANSACTION ATTRIBUTES SHOULD BE USED ON THE BUSINESS METHODS IN THE COMPONENT INTERFACE OF AN ENTITY BEAN USING #-0 #HOOSE ALL THAT APPLY
R! .OT3UPPORTED R" 2EQUIRED R# 3UPPORTS R$ 2EQUIRES.EW R% -ANDATORY R& .EVER
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HICH OF THE FOLLOWING EXCEPTIONS WOULD CAUSE A BEAN TO BE DISCARDED BY THE CONTAINER #HOOSE ALL THAT APPLY
R! MDYD[HME2EMHFW1RW)RXQG([FHSWLRQ R" MDYD[HME&UHDWH([FHSWLRQ R# MDYD[HME1R6XFK(QWLW\([FHSWLRQ R$ MDYD[HME)LQGHU([FHSWLRQ R% MDYD[HME5HPRYH([FHSWLRQ
52
)N WHICH CASES SHOULD THE CONTAINER LOG AN EXCEPTION THROWN BY A BUSINESS METHOD OF A #-4 DEMARCATED BEAN #HOOSE ALL THAT APPLY
R! )F THE METHOD RUNS WITH AN UNSPECIlED TRANSACTION CONTEXT AND THROWS A SYSTEM EXCEPTION
R" )F THE METHOD RUNS WITH AN UNSPECIlED TRANSACTION CONTEXT AND THROWS AN APPLICATION EXCEPTION
R# )F THE METHOD RUNS WITH A 2EQUIRES.EW CONTEXT AND THROWS A SYSTEM EXCEPTION
R$ )F THE METHOD RUNS WITH A 2EQUIRED CONTEXT AND THROWS A SYSTEM EXCEP TION
R% )F THE METHOD RUNS WITH A 2EQUIRES.EW CONTEXT AND THROWS AN APPLICA TION EXCEPTION
R& )F THE METHOD RUNS WITH A 2EQUIRED CONTEXT AND THROWS AN APPLICATION EXCEPTION
53
7HICH SESSION BEAN COMPONENT INTERFACE METHODS CAN BE CALLED SUCCESSFULLY BY A LOCAL CLIENT #HOOSE ALL THAT APPLY
R! UHPRYH R" JHW+DQGOH R# LV,GHQWLFDO R$ JHW(-%+RPH
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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)N WHAT SCENARIOS CAN A BEANS BUSINESS METHOD CALL THE LV&DOOHU,Q5ROH METHOD OF THE 3ESSION#ONTEXT INTERFACE #HOOSE ALL THAT APPLY
R! ! STATEFUL SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCA TION
R" ! STATELESS SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCA TION
R# ! STATEFUL SESSION BEAN WITH BEAN MANAGED TRANSACTION DEMARCATION R$ ! STATELESS SESSION BEAN WITH BEAN MANAGED TRANSACTION DEMARCATION R% .ONE OF THE ABOVE
55
7HEN CREATING AN ENTITY BEAN USING CONTAINER MANAGED PERSISTENCE WHICH CAN BE ACCESSED THROUGH THE BEANS REMOTE COMPONENT INTERFACE #HOOSE ALL THAT APPLY
R! !CCESSOR METHODS FOR THE RELATIONSHIP lELDS R" 4HE LOCAL INTERFACE OF THE ENTITY BEAN R# 4HE BEANS BUSINESS METHODS R$ 4HE COLLECTION CLASSES USED FOR CONTAINER MANAGED RELATIONSHIPS R% !CCESSOR METHODS FOR THE PERSISTENT lELDS
56
'IVEN THE CONTAINER MANAGED ONE TO ONE BIDIRECTIONAL RELATIONSHIP )RR !%DU !ND THE OBJECT RELATIONS I !E I !E 7HICH BOOLEAN EXPRESSION WILL BE TRUE AFTER THE FOLLOWING CODE RUNS E VHW)RR EJHW)RR #HOOSE ALL THAT APPLY
R!IJHW%DU QXOO R" EJHW)RR QXOO R# IJHW%DU QXOO R$ NONE OF THE ABOVE
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HATS TRUE ABOUT AN ENTITY BEANS IDENTITY #HOOSE ALL THAT APPLY
R! )F TWO ENTITY OBJECT REFERENCES ARE COMPARED USING THE OPERATOR THE CONTAINER PROVIDER IS NOT REQUIRED TO PRODUCE CONSISTENT RESULTS
R" )F TWO ENTITY OBJECT REFERENCES ARE COMPARED USING THE HTXDOV METHOD THE CONTAINER WILL RETURN TRUE IF THE TWO ENTITY OBJECTS HAVE THE SAME PRIMARY KEY
R# )F TWO ENTITY OBJECT REFERENCES ARE COMPARED USING THE LV,GHQWL FDO METHOD THE CONTAINER WILL RETURN TRUE IF THE TWO ENTITY OBJECTS HAVE THE SAME PRIMARY KEY
R$ .ONE OF THE ABOVE STATEMENTS ARE TRUE
58
'IVEN #-0 BEANS #USTOMER"EAN /RDER"EAN AND ,INE)TEMS"EAN WITH THE FOLLOWING RELATIONSHIPS #USTOMER"EAN
/RDER"EAN N /RDER"EAN
,INE)TEMS"EAN N 7HICH WILL RETURN A SET OF CUSTOMERS THAT HAVE ORDERS #HOOSE ALL THAT APPLY
R! 3%,%#4 #USTOMER
&2/- /RDER
R" 3%,%#4 $)34).#4 #USTOMER
&2/- /RDER
R# 3%,%#4 OCUSTNUM
&2/- /RDER O #USTOMER C
7(%2% CCUSTNUM OCUSTNUM
R$ 3%,%#4 /"*%#4 C
&2/- #USTOMER C /RDER O
7(%2% CCUSTNUM OCUSTNUM
R% 3%,%#4 $)34).#4 /"*%#4 C
&2/- #USTOMER C /RDER O
7(%2% CCUSTNUM OCUSTNUM
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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'IVEN 0 HWKRG 7[ !0HWKRG 7[ !0HWKRG 7[ ?!0HWKRG 7[ )F THE CALLING METHOD IS ON THE LEFT SIDE OF AN ARROW AND THE CALLED METHOD ON THE RIGHT WHICH SET OF TRANSACTION ATTRIBUTES WILL SUPPORT THE TRANSACTION SCOPE SPECIlED #HOOSE ALL THAT APPLY
R! 0 1HYHU
0 6XSSRUWV
0 5HTXLUHG
0 5HTXLUHV1HZ
R" 0 5HTXLUHG
0 6XSSRUWV
0 0DQGDWRU\
0 5HTXLUHV1HZ
R# 0 5HTXLUHV1HZ
0 5HTXLUHV1HZ
0 6XSSRUWV
0 5HTXLUHV1HZ
R$ 0 5HTXLUHG
60
0 0DQGDWRU\
0 6XSSRUWV
0 6XSSRUWV
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R! SGLVFRXQW 25SGLVFRXQW! R" SGLVFRXQW 25SGLVFRXQW! R# SGLVFRXQW 25SGLVFRXQW! R$ SGLVFRXQW 25SGLVFRXQW!
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HEN A BUSINESS METHOD IN AN ENTITY BEAN CALLS THE JHW5ROOEDFN2QO\ METHOD WHICH TRANSACTION ATTRIBUTE SETTINGS COULD CAUSE THE CONTAINER TO THROW AN EXCEPTION #HOOSE ALL THAT APPLY
R! .OT3UPPORTED R" 2EQUIRED R# 3UPPORTS R$ 2EQUIRES.EW R% -ANDATORY R& .EVER
62
7HICH OF THE FOLLOWING IS PERFORMED BY THE CONTAINER IF A MESSAGE DRIVEN BEAN DOES NOT COMPLETE ITS TRANSACTION BEFORE THE END OF THE ON-ESSAGE METHOD #HOOSE ALL THAT APPLY
R! ,OG AN APPLICATION ERROR R" 2OLL BACK THE STARTED TRANSACTION R# $ISCARD THE INSTANCE OF THE BEAN R$ 4HROW AN EXCEPTION
63
&ROM WHICH CLASSES CAN APPLICATION EXCEPTIONS EXTEND #HOOSE ALL THAT AP PLY
R! MDYDODQJ([FHSWLRQ R" MDYDODQJ5XQWLPH([FHSWLRQ R# MDYDUPL5HPRWH([FHSWLRQ R$ MDYD[HME&UHDWH([FHSWLRQ
64
7HATS TRUE ABOUT APPLICATION EXCEPTIONS #HOOSE ALL THAT APPLY
R! 4HEY ARE INTENDED TO BE HANDLED BY THE SYSTEM ADMINISTRATOR R" 4HEY SHOULD REPORT SYSTEM LEVEL PROBLEMS R# 4HEY CAUSE AUTOMATIC MARKING OF TRANSACTIONS FOR ROLLBACK R$ 4HEY MUST NOT EXTEND MDYDODQJ5XQWLPH([FHSWLRQ R% 4HEY MAY EXTENDMDYDUPL5HPRWH([FHSWLRQ
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HICH CASES CAN CAUSE A SESSION BEAN INSTANCE TO BE DESTROYED WITHOUT THE CONTAINER CALLING HME5HPRYH #HOOSE ALL THAT APPLY
R! ! TRANSACTION IS ROLLED BACK ON A STATEFUL SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCATION
R" ! SYSTEM EXCEPTION IS THROWN FROM A BUSINESS METHOD R# !N INACTIVE CLIENT IS TIMED OUT WHILE THE BEAN IS IN A PASSIVATED STATE R$ 4HE CLIENT INVOKES THE REMOVE METHOD WHILE THE BEAN IS IN A TRANSAC TION
66
7HICH DEPLOYMENT DESCRIPTOR ELEMENTS ARE USED TO SPECIFY A #OLLECTION INTERFACE #HOOSE ALL THAT APPLY
R! HMEQDPH! R" FPU¿HOG! R# HMEUHODWLRQ! R$ FPU¿HOGW\SH! R% DEVWUDFWVFKHPDQDPH!
67
)F A BEAN CATCHES A CHECKED EXCEPTION FROM WHICH IT CANNOT RECOVER WHAT SHOULD IT DO #HOOSE ALL THAT APPLY
R! )F THE CLIENT IS REMOTE THROW A MDYDUPL5HPRWH([FHSWLRQ R" 0RINT A STACK TRACE R# 2EGARDLESS OF THE CLIENT THROW A MDYD[HME(-%([FHSWLRQ R$ 2EGARDLESS OF THE CLIENT PROPAGATE THE SAME EXCEPTION TO THE CONTAIN ER
68
7HICH ARE REQUIREMENTS FOR A #-0 ENTITY BEAN CLASS #HOOSE ALL THAT APPLY
R! !LL HME6HOHFW METHODS MUST BE DECLARED AS ABSTRACT R" 4HE CLASS MUST ./4 DElNE AN HME&UHDWH METHOD R# 4HE HME3RVW&UHDWH METHODS ARE IMPLEMENTED BY THE CONTAINER R$ (ELPER METHODS MUST ./4 BE IMPLEMENTED IN THE BEAN CLASS R% -ETHODS STARTING WITH @HME)LQG MUST NOT BE IMPLEMENTED
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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7HICH ARE VALID DEPLOYMENT DESCRIPTOR SEGMENTS TO DElNE A CMR lELD #HOOSE ALL THAT APPLY
R! HMEUHODWLRQVKLSUROH!
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FPU¿HOG!
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R# UHODWLRQVKLSUROHVRXUFH!
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R$ UHODWLRQVKLSUROHVRXUFH!
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7HATS TRUE ABOUT A REMOTE CLIENTS VIEW OF EXCEPTIONS RECEIVED FROM AN ENTITY BEAN #HOOSE ALL THAT APPLY
R! )F THE CONTAINER MARKS A TRANSACTION FOR ROLLBACK THE CONTAINER WILL ALWAYS ISSUE A MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5ROOHGEDFN([FH SWLRQ EXCEPTION
R" )F THE CLIENT RECEIVES A MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5ROOHG %DFN([FHSWLRQ THE CONTAINER GUARANTEES THAT THAT TRANSACTION WILL NEVER COMMIT
R# ! MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5HTXLUHG([FHSWLRQ EXCEP TION INFORMS THE CLIENT THAT THE BEAN NEEDED TO BE CALLED WITHIN THE CONTEXT OF A TRANSACTION
R$ )F THE CONTAINER DISCOVERS THAT A REQUESTED BEAN NO LONGER EXISTS IT WILL ALWAYS THROW THE MDYD[HME1R6XFK2EMHFW(QWLW\([FHSWLRQ
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 24
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7HICH ARE BENElTS OF %*" #HOOSE ALL THAT APPLY
(spec: 108)
R! -$"S SURVIVE SERVER CRASHES R" 2EPRESENTATIONS OF A SINGLE ENTITY CAN BE SHARED AMONG MULTIPLE CLI ENTS
R# 3UPPORT FOR NESTED TRANSACTIONS R$ $YNAMIC SERVICE DISCOVERY - ThatÕs a Jini thing R% $ECLARATIVE ISOLATION LEVEL SETTINGS
2
7HICH METHODS ARE DIRECTLY INVOKED BY THE CLIENT #HOOSE ALL THAT APPLY
3
7HICH METHODS CAN BE FOUND IN THE %*"(OME INTERFACE #HOOSE ALL THAT APPLY
R! HME3DVVLYDWH - invoked by the Container R" BUSINESS METHODS R# VHW6HVVLRQ&RQWH[W R$ QHZ,QVWDQFH - invoked by the Container R% FUHDWH
(API docs)
R! REMOVE(ANDLE HANDLE R" REMOVE/BJECT PRIMARY+EY R# GET(ANDLE - this is in EJBObject R$ NONE OF THE ABOVE
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DSSHQGL[$ILQDOPRFNH[DP
4
7HICH METHODS CAN BE RUN BY A #-0 BEAN IN THE POOLED STATE #HOOSE ALL THAT APPLY
R! HME/RDG R" HME)LQG R# HME6WRUH R$ HME&UHDWH R% "USINESS METHOD R& HME+RPH
5
(spec: 168)
- The bean doesnÕt leave the pool for home and Þnder methods
(spec: 314, 316,
7HATS TRUE ABOUT MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
324)
R! !LL CALLS TO A MESSAGE DRIVEN BEAN INSTANCE MUST BE SERIALIZED R" 4HE CONTAINER GUARANTEES THAT MESSAGES WILL BE PROCESSED IN THE ORDER IN WHICH THEY ARE RECEIVED
must have a no-arg create, R# 4HE BEANS HME&UHDWH METHOD MUST TAKE A SINGLE ARGUMENT OF TYPE onMessag e takes the MDYD[MPV0HVVDJH
message as its argument
R$ 4HE BEAN PROVIDER USES THE DEPLOYMENT DESCRIPTOR TO INDICATE WHETHER INSTANCES OF THE BEAN CLASS ARE INTENDED FOR TOPICS OR QUEUES
6
7HATS TRUE ABOUT AN ENTERPRISE BEANS ENVIRONMENT #HOOSE ALL THAT APPLY
(spec: 412-413)
R! "EFORE A BEAN CAN ACCESS ITS ENVIRONMENT ENTRIES THE BEAN MUST lRST
the Deployer or typically seAtssbyembler R" /NLY THE BEAN PROVIDER CAN SET AN ENVIRONMENT ENTRY VALUE Application R# ! BEANS ENVIRONMENT ENTRIES CAN BE STORED ONLY IN - donÕt confuse a JNDI context and an µMDYD FRPSHQY¶OR ONE OF ITS SUBCONTEXTS EJBContext (like SessionContext) OBTAIN THE NAMING CONTEXT USING A 6HVVLRQ&RQWH[W OBJECT
R$ %VERY ENVIRONMENT ENTRY LOOKUP IN A BEANS CODE MUST HAVE A MATCHING HQYHQWU\! ELEMENT IN THE BEANS DEPLOYMENT DESCRIPTOR
7
- otherwise the code would have nothing to look up!
7HATS TRUE ABOUT SECURITY ROLES IN %*"S #HOOSE ALL THAT APPLY
R! 3ECURITY ROLES ARE DElNED IN THE DEPLOYMENT DESCRIPTOR USING SECURITY
3)
(spec: 440-44
ROLE ELEMENTS
R" 3ECURITY ROLES ARE SCOPED TO THE INSTANCE LEVEL R# -ANY METHODS CAN BE MAPPED TO A SINGLE SECURITY ROLE R$ ! METHOD CAN APPEAR IN ONLY ONE SECURITY ROLE
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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PRFNH[DPDQVZHUV
8
!N %*" CONTAINER MUST SUPPORT AT LEAST A SUBSET OF WHICH !0)S #HOOSE ALL THAT APPLY
) (spec: 493-493
R! *4! R" *$"# R# *-3 R$ *!8 2#0
9
7HICH STATEMENTS CONCERNING STATELESS SESSION BEANS ARE TRUE #HOOSE ALL THAT APPLY
(spec: 95)
R! 4HEY CAN USE BEAN MANAGED TRANSACTION DEMARCATION R" 4HEY MUST HAVE ONE NO ARGUMENT CREATE METHOD R# ! SINGLE INSTANCE CAN SUPPORT CONCURRENT CALLS R$ 4HEY MUST EXTEND JAVAXEJB3ESSION"EAN - implements : )
10
7HAT CAPABILITY EXISTS IN /.,9 /.% OF THE TWO BUT NOT BOTH AN ENTITY OBJECTS REMOTE COMPONENT INTERFACE AN ENTITY OBJECTS LOCAL COMPONENT INTERFACE #HOOSE ALL THAT APPLY
R! 2EMOVING THE OBJECT R" /BTAINING THE OBJECTS HANDLE not for local interfaces R# )NVOKING BUSINESS METHODS R$ /BTAINING THE OBJECTS PRIMARY KEY
11
7HEN CREATING A #-0 ENTITY BEAN WHICH METHODS ARE OPTIONAL #HOOSE ALL THAT APPLY
(spec: 171-174)
R! HME/RDG nts have to allow clie R" HME&UHDWH - you donÕtnew entities to insert R# HME5HPRYH R$ HME6HOHFW R% HME3DVVLYDWH R& VHW(QWLW\&RQWH[W
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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DSSHQGL[$ILQDOPRFNH[DP
12
R! HME)LQG R" HME/RDG R# HME6WRUH R$ HME6HOHFW R% HME3DVVLYDWH
13
(spec: 168)
7HICH METHODS CAN BE CALLED ON A BEAN IN THE POOLED STATE #HOOSE ALL THAT APPLY
Þnder and seenleÕtctspeciÞc methods arty to one enti
(spec: 318-320)
7HATS TRUE ABOUT THE LIFECYCLE OF A MESSAGE DRIVEN BEAN #HOOSE ALL THAT AP PLY
R! 7HEN THE THE OQ0HVVDJH METHOD COMPLETES THE CONTAINER WILL TYPI CALLY CALL EJB2EMOVE
- bean just goes back to the pool
R" 4HE ON0HVVDJH METHOD CAN THROW APPLICATION EXCEPTIONS - to whom ? R# -ESSAGE DRIVEN BEANS CAN RUN ONLY WITH #-4 DEMARCATION R$ 4HE JHW5ROOEDFN2QO\ METHOD CAN BE CALLED ONLY FROM THE ON-ESSAGE METHOD
14
7HICH STATEMENTS CONCERNING MESSAGE DRIVEN BEAN CLASSES ARE TRUE #HOOSE ALL THAT APPLY
(spec: 323)
R! 4HEY MUST IMPLEMENT DIRECTLY OR INDIRECTLY MDYD[MPV0HVVDJH - itÕs MessageListener R" 4HEY MUST HAVE A PUBLIC CONSTRUCTOR THAT TAKES A SINGLE ARGUMENT OF TYPE MDYD[MPV0HVVDJH
R# )MPLEMENTING THE ¿QDOL]H METHOD IS ALLOWED -No! not in any bean R$ )MPLEMENTING THE HME&UHDWH METHOD IS OPTIONAL R% 4HE CLASS MUST NOT BE DECLARED @lNAL- the Container might want to dep
loy a subclass of your bean
15
7ITHIN THE DEPLOYMENT DESCRIPTORS HMEORFDOUHI! ELEMENT WHICH ELE (spec: MENTS ARE OPTIONAL #HOOSE ALL THAT APPLY
466)
R! ORFDO! R" HMEOLQN! R# ORFDOKRPH! R$ GHVFULSWLRQ! R% HMEUHIQDPH! R& HMEUHIW\SH! \RXDUHKHUH
Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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PRFNH[DPDQVZHUV
16
7HATS TRUE ABOUT RESOURCE MANAGER CONNECTION FACTORIES #HOOSE ALL THAT APPLY
)
(spec: 423, 481
R4HE UHVVKDULQJVFRSH! DEPLOYMENT DESCRIPTOR ELEMENT IS USED TO INDICATE WHETHER CONNECTIONS TO A RESOURCE MANAGER ARE SHAREABLE ACROSS MULTIPLE %*"S IN AN APPLICATION
R" 4HE UHVVKDULQJVFRSH! DEPLOYMENT DESCRIPTOR ELEMENT CONTAINS - backwards THE UHVRXUFHUHI! ELEMENT
R# !LL OF A BEANS RESOURCE MANAGER CONNECTION FACTORY REFERENCES ARE - each must be individually DECLARED IN A SINGLE UHVRXUFHUHI! ELEMENT USING UHVUHIQDPH! ELEMENTS TO DISTINGUISH THEM
speciÞed with a
R$ "Y DEFAULT CONNECTIONS TO A GIVEN RESOURCE MANAGER ARE SHAREABLE ACROSS MULTIPLE BEANS IN AN APPLICATION
17
7HATS TRUE ABOUT SECURITY ROLES REFERENCED FROM AN %*"S CODE #HOOSE ALL THAT APPLY
(spec: 439-441,
446)
R! )N THE DEPLOYMENT DESCRIPTOR SUCH REFERENCES ARE CONTAINED IN THE VHFXULW\UROHUHI! ELEMENT
R" 4HE VHFXULW\UROH! ELEMENT INCLUDES THE
VHFXULW\UROHUHI! ELEMENT
is NOT the same as a real R# 7ITHIN THE VHFXULW\UROHUHI! ELEMENT THE UROHQDPH! - this role name ELEMENTS VALUE IS THE SAME AS THE ARGUMENT FOR THE BEANS INVOCATION OF THE LV&DOOHU,Q5ROH METHOD
R$ 4HE UROHOLQN! ELEMENT IS USED TO LINK TWO - no, it links a to a VHFXULW\UROHUHI! ELEMENTS
18
7HATS TRUE ABOUT THE CLIENTS VIEW OF SECURITY #HOOSE ALL THAT APPLY
(spec: 450)
R! ! TRANSACTIONAL CLIENT CANNOT CHANGE ITS PRINCIPAL ASSOCIATION WITHIN A TRANSACTION
R" ! SESSION BEANS CLIENT CANNOT CHANGE ITS PRINCIPAL ASSOCIATION FOR THE DURATION OF THE COMMUNICATION WITH THE SESSION OBJECT
R# 4RANSACTIONAL REQUESTS WITHIN A SINGLE TRANSACTION CANNOT ARRIVE FROM MULTIPLE CLIENTS
R$ .ONE OF THE ABOVE
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 29
DSSHQGL[$ILQDOPRFNH[DP
19
7HEN PROGRAMMING AN ENTITY BEAN CLASS WHICH TECHNIQUES SHOULD BE !6/)$%$ TO ENSURE BEAN PORTABILITY ACROSS ALL %*" CONTAINERS #HOOSE ALL THAT APPLY
) (spec: 494-495
R! #HANGING A THREADS PRIORITY R" 5SING THE REmECTION !0) R# 5SING WRAPPER CLASSES R$ 5SING STATIC NESTED CLASSES
20
7HEN PROGRAMMING A MESSAGE DRIVEN BEAN CLASS WHICH TECHNIQUES SHOULD BE AVOIDED TO ENSURE BEAN PORTABILITY ACROSS ALL %*" CONTAINERS #HOOSE ALL THAT APPLY
)
(spec: 494-495
R! 5SING 3WING !0)S FOR A '5) R" 5SING THE @TRANSIENT MODIlER R# 5SING NATIVE LIBRARIES R$ 2EADING lLE DESCRIPTORS
21
7HAT IS REQUIRED OF THE CONTAINER WHEN IT PASSIVATES A STATEFUL SESSION BEAN
(spec: 71)
R! 4HE BEANS INSTANCE STATE WILL ALWAYS UNDERGO *AVA PROGRAMMING LAN GUAGE 3ERIALIZATION
- it might be something similar
R" )T MUST SAVE ALL OF THE BEANS INSTANCE lELD STATE REGARDLESS OF THE lELDS MODIlERS
R# )T MUST SAVE ANY REFERENCES TO THE BEANS 3ESSION#ONTEXT OBJECT R$ )T MUST SAVE ALL NON NULL TRANSIENT VARIABLES - no, it wonÕt save transient variables, but
it might not reset them to default values...
22
7HICH CAPABILITIES ARE DElNED IN THE MDYD[HME(-%/RFDO2EMHFW INTER FACE #HOOSE ALL THAT APPLY
R! 2EMOVE AN ENTITY OBJECT R" /BTAIN AN ENTITY OBJECTS PRIMARY KEY R# /BTAIN A LOCAL HOME INTERFACE FOR THE ENTITY OBJECT R$ /BTAIN A REMOTE COMPONENT INTERFACE FOR THE ENTITY OBJECT R% %XPOSE THE METHODS OF THE MDYD[HME(QWLW\%HDQ INTERFACE TO THE CLIENT
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 30
PRFNH[DPDQVZHUV
23
7HATS TRUE ABOUT EJB3ELECT METHODS #HOOSE ALL THAT APPLY
(spec: 183)
R! 4HEY CAN BE EXPOSED TO THE CLIENT R" 4HEY CAN RETURN ONLY %*"/BJECTS OR %*",OCAL/BJECTS - They can return almost anything R# 4HEY CAN BE INVOKED ONLY BY A BEAN IN THE READY STATE - No, theyÕre good for home biz methods R$ 4HEY MUST BE ASSOCIATED WITH A QUERY ELEMENT IN THE DEPLOYMENT DE SCRIPTOR
24
7HICH METHODS CAN .%6%2 BE SUCCESSFULLY INVOKED FROM A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
R! LV&DOOHU,Q5ROH R" JHW(-%+RPH R# JHW5ROOEDFN2QO\ R$ VHW5ROOEDFN2QO\ R% JHW&DOOHU3ULQFLSDO
25
(spec: 320-321)
ient MDBs haveeynohaclve no th so , view curity home or clien nt se io informat
7HICH ROLE IS TYPICALLY RESPONSIBLE FOR ADDING EJB LINK ELEMENTS TO AN %*"S DEPLOYMENT DESCRIPTOR
(spec: 418)
R! BEAN PROVIDER R" APPLICATION ASSEMBLER - linking one bean that refers to another R# DEPLOYER R$ CONTAINER PROVIDER R% SYSTEM ADMINISTRATOR
26
)N WHICH OF THE FOLLOWING METHODS CAN A STATELESS SESSION BEAN INVOKE THE LV&DOOHU,Q5ROH METHOD IN ORDER TO PERFORM A SECURITY CHECK #HOOSE ALL THAT APPLY
R! HME&UHDWH R" HME5HPRYH R# VHW6HVVLRQ&RQWH[W R$ .ONE OF THE ABOVE
(spec: 90)
- isCallerInRole() can be called from business methods only
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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27
7HICH TWO ARE TYPICALLY RESPONSIBLE FOR CREATING EJB JAR lLES #HOOSE TWO
28
7HICH OF THE FOLLOWING STATELESS SESSION BEAN CONTAINER CALLBACK METHODS TAKES AN ARGUMENT #HOOSE ALL THAT APPLY
(spec: 487)
R! 4HE BEAN PROVIDER R" 4HE APPLICATION ASSEMBLER R# 4HE DEPLOYER R$ 4HE SYSTEM ADMINISTRATOR
(spec: 77)
R! HME5HPRYH R" HME&UHDWH R# HME&UHDWH R$ HME3DVVLYDWH object a SessionContext R% VHW6HVVLRQ&RQWH[W - takes
29
(spec: 74)
7HICH OF THESE CAN NEVER BE CALLED ON A 3ESSION#ONTEXT INTERFACE #HOOSE ALL THAT APPLY
R! JHW(-%+RPH R" JHW(-%2EMHFW R# JHW(-%7UDQVDFWLRQ - no such method : ) R$ LV&DOOHU,Q5ROH R% JHW8VHU7UDQVDFWLRQ
30
(spec: 190)
7HATS TRUE ABOUT AN ENTITY BEANS REMOTE COMPONENT INTERFACE #HOOSE ALL THAT APPLY
R! )F A CLIENT ATTEMPTS TO INVOKE A METHOD ON AN ENTITY THAT DOES NOT EXIST A MDYDUPL1R6XFK5HPRWH2EMHFW([FHSWLRQ WILL BE THROWN
- itÕs NoSuchObjectException
R" )T MUST EXTEND MDYD[HME(-%+RPH - itÕs EJBObject R# )TS METHODS MUST DECLAREMDYDUPL5HPRWH([FHSWLRQ R$ )T DElNES AUHPRYH +DQGOHKDQGOH METHOD - This is only in the hom
e
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 32
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31
7HICH ARE TRUE ABOUT lNDER METHODS IN AN ENTITY BEANS LOCAL HOME INTERFACE #HOOSE ALL THAT APPLY
(spec: 196)
R! 4HEY CAN HAVE ANY LEGAL *AVA NAME - must start with ÒÞndÓ R" 4HEY MUST ALL DECLARE MDYD[HME)LQGHU([FHSWLRQ R# 4HEY CAN OPTIONALLY DECLARE MDYDUPL5HPRWH([FHSWLRQ - not in a local interface! R$ 4HE ¿QG%\3ULPDU\.H\ METHOD CAN BE OVERLOADED R% 4HE ¿QG%\3ULPDU\.H\ METHODS RETURN TYPE MUST BE THE BEANS LOCAL COMPONENT INTERFACE
R& ! METHOD CALLED hlND888v MUST HAVE THE BEANS LOCAL COMPONENT INTERFACE AS ITS DECLARED RETURN TYPE
32
- it could also be a Collection
7HICH ARE TRUE FOR A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
(spec: 324-325,
317)
R! 4HE $EPLOYER USES THE DEPLOYMENT DESCRIPTOR TO DETERMINE WHETHER A BEAN IS INTENDED FOR A 1UEUE OR A 4OPIC
R" 4HE CLASS MUST BE DECLARED lNAL R# 4HE CLASS MUST DElNE ONE HME5HPRYH METHOD R$ 4HE CLASS CAN HAVE OVERLOADED HME&UHDWH METHODS - thereÕs no client R% 4HE CLASS MUST DElNE A NO ARGUMENT ON-ESSAGE METHOD - onMessage takes a message
33
'IVEN THE FOLLOWING SUBSET OF A DEPLOYMENT DESCRIPTOR HQWLW\!
(spec: 440)
HMEQDPH!3D\UROO HMEQDPH! VHFXULW\UROHUHI! UROHQDPH!FOHUN UROHQDPH! VHFXULW\UROHUHI! HQWLW\! 7HICH CODE SNIPPETS MAKES A LEGAL SECURITY CHECK #HOOSE ALL THAT APPLY
R! FRQWH[WLV&DOOHU,Q5ROH ³3D\UROO´ R" FRQWH[WLV&DOOHU,Q5ROH ³FOHUN´ R# FRQWH[WLV&DOOHU,Q5ROH ³3D\UROOFOHUN´ R$ FRQWH[WLV&DOOHU,Q5ROH ³3D\UROOFOHUN´
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 33
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34
7HICH ARE VALID LOCAL HOME INTERFACES FOR A STATEFUL SESSION BEAN #HOOSE ALL THAT APPLY
(spec: 98)
R! SXEOLFLQWHUIDFH7HVW%HDQLPSOHPHQWV MDYD[HME(-%/RFDO+RPH^ Y RLGFUHDWH WKURZV&UHDWH([FHSWLRQ `
R" SXEOLFLQWHUIDFH7HVW%HDQH[WHQGV
Must: - throw CreateException - return local interface type - start with ÒcreateÓ - NOT throw RemoteException
MDYD[HME(-%/RFDO+RPH^ 7 HVW%HDQ/RFDOHME&UHDWH WKURZV&UHDWH([FHSWLRQ `
R# SXEOLFLQWHUIDFH7HVW%HDQH[WHQGV MDYD[HME(-%/RFDO+RPH^
7HVW%HDQ/RFDOFUHDWH WKURZV&UHDWH([FHSWLRQ
`
R$ SXEOLFLQWHUIDFH7HVW%HDQH[WHQGV MDYD[HME(-%/RFDO+RPH^ 7 HVW%HDQ/RFDOFUHDWH WKURZV&UHDWH([FHSWLRQ 5HPRWH([FHSWLRQ `
R% SXEOLFLQWHUIDFH7HVW%HDQH[WHQGV MDYD[HME(-%/RFDO+RPH^ 7 HVW%HDQ/RFDOFUHDWH WKURZV/RFDO([FHSWLRQ `
35
7HICH METHODS CAN BE CALLED BY A BEAN PROVIDER #HOOSE ALL THAT APPLY
R! UHPRYH - the callback is ejbRemove R" HME&UHDWH R# DIWHU%HJLQ The others caarllbe acks Container R$ JHW&DOOHU3ULQFLSDO R% HME3DVVLYDWH
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 34
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36
7HO WILL TYPICALLY SPECIFY WHETHER A BEAN IS RE ENTRANT IN THE BEANS DEPLOY MENT DESCRIPTOR
(spec: 457)
R! 4HE BEAN PROVIDER R" 4HE APPLICATION ASSEMBLER R# 4HE DEPLOYER R$ 4HE SYSTEM ADMINISTRATOR
37
7HICH STATEMENTS ABOUT STATEFUL AND STATELESS SESSION BEANS ARE TRUE #HOOSE ALL THAT APPLY
R! /NLY STATEFUL SESSION BEANS SUPPORT TRANSACTIONS R" /NLY STATEFUL SESSION BEANS CAN BE PASSIVATED R# /NLY STATEFUL SESSION BEANS HAVE A µVHW6HVVLRQ&RQWH[W¶ METHOD single, eless must have a R$ "OTH STATEFUL AND STATELESS SESSION BEANS CAN SUPPORT OVERLOADED - statrg ejbCreate µHME&UHDWH¶METHODS
no-a
R% "OTH STATEFUL AND STATELESS SESSION BEANS CAN IMPLEMENT THE- only stateful
38
have state, - stateless iecantn -s peciÞc R& "OTH STATEFUL AND STATELESS SESSION BEANS CAN HAVE INSTANCE VARIABLE STATE just not cl e at st ) 7HICH MUST BE INCLUDED IN EVERY EJB JAR lLE #HOOSE ALL THAT APPLY (spec: 488-490
39
7HICH METHODS ARE DECLARED IN THE JAVAXEJB%*"(OME INTERFACE #HOOSE ALL THAT APPLY
MDYD[HME6HVVLRQ6\QFKURQL]DWLRQ INTERFACE
R! 4HE STUB FOR THE %*"(OME INTERFACE EITHER DIRECTLY OR BY REFERENCE - This is the ContainerÕs jo R" 4HE *!2 -ANIFEST lLE - not ne b eded as of EJ B 2.0 R# ! DEPLOYMENT DESCRIPTOR R$ 4HE *.$) CONTEXT R% 4HE %*"S HOME INTERFACE EITHER DIRECTLY OR BY REFERENCE
(API docs)
R! FUHDWH R" ORRNXS R# JHW+DQGOH R$ JHW+RPH+DQGOH R% VHW6HVVLRQ&RQWH[W
DSSHQGL[$
Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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Page 35
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40
(OW MANY JAVAXEJB%*",OCAL(OME INTERFACE METHODS CAN BE CALLED WITHOUT AN EXCEPTION FROM A SESSION BEAN CLIENT
R! R" R# R$ R%
41
(spec: 60)
The only method in EJBLocalHome is remove that takes a primary key
7HICH OF THE FOLLOWING IF CALLED ALWAYS HAVE THE SAME TRANSACTION CONTEXT AS A SESSION BEANS BUSINESS METHODS #HOOSE ALL THAT APPLY
(spec: 76)
R! CONSTRUCTOR R" VHW6HVVLRQ&RQWH[W R# DIWHU%HJLQ R$ DIWHU&RPSOHWLRQ - transaction is over R% EHIRUH&RPSOHWLRQ
42
'IVEN A STATEFUL SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCATION FROM WHICH METHODS CAN YOU ACCESS ANOTHER BEAN #HOOSE ALL THAT APPLY
R! VHW6HVVLRQ&RQWH[W R" HME&UHDWH R# DIWHU%HJLQ R$ EHIRUH&RPSOHWLRQ R% DIWHU&RPSOHWLRQ
43
(spec: 80)
setSessionContext and afterCompletion have NO meaningful tx context
7HICH DEPLOYMENT DESCRIPTOR ELEMENTS CAN OPTIONALLY SPECIFY CASCADE DELETE FUNCTIONALITY #HOOSE ALL THAT APPLY
(spec: 468)
R! HMEUHODWLRQ! R" DEVWUDFWVFKHPDQDPH! R# HMEUHODWLRQVKLSUROH! R$ UHODWLRQVKLSUROHVRXUFH!
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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PRFNH[DPDQVZHUV
44
7HATS TRUE ABOUT CASCADE DELETE #HOOSE ALL THAT APPLY
(spec: 133)
R! )T IS DECLARED IN THE HME5HPRYH METHOD - cascade-delete says Òdelete R" 7HEN A CASCADE DELETE ENABLED BEAN IS DELETED IT CAUSES ALL OF THE ME if my partner is removedÓ BEANS WITH RELATIONSHIPS TO IT TO BE AUTOMATICALLY DELETED TOO
R# )T CAN BE SPECIlED FOR ONE TO ONE ONE TO MANY OR MANY TO MANY RELA - not for many-to-many TIONSHIPS
R$ ! CASCADE DELETE ENABLED BEAN IS AUTOMATICALLY REMOVED WHEN ANY hMULTIPLICITY OF ONEv BEAN WITH WHICH IT IS RELATED IS REMOVED
45
7HICH METHODS FROM THE %NTITY#ONTEXT INTERFACE CAN BE INVOKED REGARDLESS OF TRANSACTION CONTEXT #HOOSE ALL THAT APPLY
(spec: 180)
R! JHW(-%+RPH R" JHW(-%2EMHFW R# VHW5ROOEDFN2QO\ R$ JHW5ROOEDFN2QO\
46
7HATS TRUE ABOUT AN ENTITY BEANS PRIMARY KEY #HOOSE ALL THAT APPLY
(spec: 120, 130)
R! 0RIMARY KEY lELDS MUST BE CMP lELDS - you can use a compound key R" 3ETTER METHODS FOR lELDS ASSOCIATED WITH A PRIMARY KEY MUST NOT BE EXPOSED THROUGH A CLIENT VIEW
R# )F TWO ENTITY OBJECTS HAVE THE SAME HOME AND THE SAME PRIMARY KEY THEY ARE CONSIDERED IDENTICAL
R$ 4HE JHW3ULPDU\.H\ METHOD CAN BE INVOKED ON REFERENCES TO ONLY REMOTE HOME INTERFACES NOT LOCAL HOME INTERFACES
47
7HICH INTERFACES ARE USED BY THE BEAN PROVIDER TO PERFORM "-4 DEMARCA TION #HOOSE ALL THAT APPLY
(spec: 332)
R! MDYD[WUDQVDFWLRQ7UDQVDFWLRQ R" MDYD[WUDQVDFWLRQ8VHU7UDQVDFWLRQ R# MDYD[WUDQVDFWLRQ6\QFKURQL]DWLRQ R$ MDYD[WUDQVDFWLRQ7UDQVDFWLRQ0DQDJHU
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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DSSHQGL[$ILQDOPRFNH[DP
48
7HICH OF THE FOLLOWING ARE LEGAL %*" 1, QUERIES #HOOSE ALL THAT APPLY
(spec: 236)
R! 3%,%#4 C -needs Object (c) or a path
&2/- #USTOMER C
R" 3%,%#4 /"*%#4 CNAME - Just all wrong! must be OBJECT(c) or
&2/- #USTOMER C
R# 3%,%#4 /"*%#4 C
7(%2% #USTOMER C
c.name (see answers D and E)
- must have a FROM, and (c)
R$ 3%,%#4 /"*%#4 C
&2/- #USTOMER C
R% 3%,%#4 CNAME
49
&2/- #USTOMER C
7HICH ARE TRUE ABOUT TRANSACTIONS IN %*" #HOOSE ALL THAT APPLY
(spec: 339, 348)
- This would elinimate a key R! /NLY ONE DATABASE CAN BE UPDATED WITHIN A SINGLE TRANSACTION EJB 2.0 feature of R" %NTITY BEANS WITH "-4 DEMARCATION MUST USE THE SET3TATUS METHOD distributed transactions INSTEAD OF THE VHW5ROOEDFN2QO\ METHOD
R# %NTITY BEANS WITH "-4 DEMARCATION MUST USE THE GET3TATUS METHOD INSTEAD OF THE JHW5ROOEDFN2QO\ METHOD
R$ "-4 DEMARCATION SHOULD BE USED WHEN BEANS ACCESS RESOURCE MANAG - use CMT ERS THAT DO NOT SUPPORT TRANSACTIONS
with ÒNotSuppo
rtedÓ
R% 4HE @3ESSION3YNCHRONIZATION INTERFACE CAN BE USED ONLY BY STATEFUL SESSION BEANS
50
4O ENSURE BEAN PORTABILITY WHICH TRANSACTION ATTRIBUTES SHOULD BE USED ON THE BUSINESS METHODS IN THE COMPONENT INTERFACE OF AN ENTITY BEAN USING #-0 #HOOSE ALL THAT APPLY
(spec: 352)
R! .OT3UPPORTED R" 2EQUIRED R# 3UPPORTS R$ 2EQUIRES.EW R% -ANDATORY R& .EVER
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51
7HICH OF THE FOLLOWING EXCEPTIONS WOULD CAUSE A BEAN TO BE DISCARDED BY THE CONTAINER #HOOSE ALL THAT APPLY
R! MDYD[HME2EMHFW1RW)RXQG([FHSWLRQ R" MDYD[HME&UHDWH([FHSWLRQ R# MDYD[HME1R6XFK(QWLW\([FHSWLRQ R$ MDYD[HME)LQGHU([FHSWLRQ R% MDYD[HME5HPRYH([FHSWLRQ
52
)
(spec: 372-374
The others are recoverable application exceptions
)N WHICH CASES SHOULD THE CONTAINER LOG AN EXCEPTION THROWN BY A BUSINESS METHOD OF A #-4 DEMARCATED BEAN #HOOSE ALL THAT APPLY
(spec: 376)
R! )F THE METHOD RUNS WITH AN UNSPECIlED TRANSACTION CONTEXT AND THROWS A SYSTEM EXCEPTION
R" )F THE METHOD RUNS WITH AN UNSPECIlED TRANSACTION CONTEXT AND THROWS
- system exceptions are always logged
AN APPLICATION EXCEPTION
R# )F THE METHOD RUNS WITH A 2EQUIRES.EW CONTEXT AND THROWS A SYSTEM EXCEPTION
R$ )F THE METHOD RUNS WITH A 2EQUIRED CONTEXT AND THROWS A SYSTEM EXCEP TION
R% )F THE METHOD RUNS WITH A 2EQUIRES.EW CONTEXT AND THROWS AN APPLICA TION EXCEPTION
R& )F THE METHOD RUNS WITH A 2EQUIRED CONTEXT AND THROWS AN APPLICATION EXCEPTION
53
7HICH SESSION BEAN COMPONENT INTERFACE METHODS CAN BE CALLED SUCCESSFULLY BY A LOCAL CLIENT #HOOSE ALL THAT APPLY
R! UHPRYH R" JHW+DQGOH - local client views donÕt have handles R# LV,GHQWLFDO R$ JHW(-%+RPH - should
be getEJBLoc alHome()
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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54
)N WHAT SCENARIOS CAN A BEANS BUSINESS METHOD CALL THE LV&DOOHU,Q5ROH METHOD OF THE 3ESSION#ONTEXT INTERFACE #HOOSE ALL THAT APPLY
Transaction demarcation
R! ! STATEFUL SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCA doesnÕt matter here TION
R" ! STATELESS SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCA TION
R# ! STATEFUL SESSION BEAN WITH BEAN MANAGED TRANSACTION DEMARCATION R$ ! STATELESS SESSION BEAN WITH BEAN MANAGED TRANSACTION DEMARCATION R% .ONE OF THE ABOVE
55
7HEN CREATING AN ENTITY BEAN USING CONTAINER MANAGED PERSISTENCE WHICH CAN BE ACCESSED THROUGH THE BEANS REMOTE COMPONENT INTERFACE #HOOSE ALL THAT APPLY
(spec: 130)
R! !CCESSOR METHODS FOR THE RELATIONSHIP lELDS R" 4HE LOCAL INTERFACE OF THE ENTITY BEAN R# 4HE BEANS BUSINESS METHODS R$ 4HE COLLECTION CLASSES USED FOR CONTAINER MANAGED RELATIONSHIPS idea... R% !CCESSOR METHODS FOR THE PERSISTENT lELDS - legal, just not a good
56
'IVEN THE CONTAINER MANAGED ONE TO ONE BIDIRECTIONAL RELATIONSHIP
(spec: 138)
)RR !%DU !ND THE OBJECT RELATIONS I !E I !E 7HICH BOOLEAN EXPRESSION WILL BE TRUE AFTER THE FOLLOWING CODE RUNS E VHW)RR EJHW)RR #HOOSE ALL THAT APPLY
R!IJHW%DU QXOO R" EJHW)RR QXOO R# IJHW%DU QXOO R$ NONE OF THE ABOVE
When b2 took b1Õs Foo, he replaced his own foo2 with foo1. So now, foo2 has no bar. I E IE
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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57
7HATS TRUE ABOUT AN ENTITY BEANS IDENTITY #HOOSE ALL THAT APPLY
R! )F TWO ENTITY OBJECT REFERENCES ARE COMPARED USING THE OPERATOR THE
(spec: 121)
CONTAINER PROVIDER IS NOT REQUIRED TO PRODUCE CONSISTENT RESULTS
R" )F TWO ENTITY OBJECT REFERENCES ARE COMPARED USING THE HTXDOV METHOD THE CONTAINER WILL RETURN TRUE IF THE TWO ENTITY OBJECTS HAVE THE SAME PRIMARY KEY - not guaranteed
R# )F TWO ENTITY OBJECT REFERENCES ARE COMPARED USING THE LV,GHQWLFDO METHOD THE CONTAINER WILL RETURN TRUE IF THE TWO ENTITY OBJECTS HAVE THE SAME PRIMARY KEY
R$ .ONE OF THE ABOVE STATEMENTS ARE TRUE
58
'IVEN #-0 BEANS #USTOMER"EAN /RDER"EAN AND ,INE)TEMS"EAN WITH THE FOLLOWING RELATIONSHIPS
(spec: 232)
#USTOMER"EAN
/RDER"EAN N /RDER"EAN
,INE)TEMS"EAN N 7HICH WILL RETURN A SET OF CUSTOMERS THAT HAVE ORDERS #HOOSE ALL THAT APPLY
R! 3%,%#4 #USTOMER - need OBJECT or path
&2/- /RDER
R" 3%,%#4 $)34).#4 #USTOMER
- need OBJECT or path
&2/- /RDER
R# 3%,%#4 OCUSTNUM
&2/- /RDER O #USTOMER C
7(%2% CCUSTNUM OCUSTNUM
R$ 3%,%#4 /"*%#4 C
&2/- #USTOMER C /RDER O
7(%2% CCUSTNUM OCUSTNUM
- not a Customer type - doesnÕt guarantee you wonÕt get duplicates
R% 3%,%#4 $)34).#4 /"*%#4 C
&2/- #USTOMER C /RDER O
7(%2% CCUSTNUM OCUSTNUM
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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DSSHQGL[$ILQDOPRFNH[DP
59
'IVEN 0 HWKRG 7[ !0HWKRG 7[ !0HWKRG 7[
(spec: 357-359)
?!0HWKRG 7[ )F THE CALLING METHOD IS ON THE LEFT SIDE OF AN ARROW AND THE CALLED METHOD ON THE RIGHT WHICH SET OF TRANSACTION ATTRIBUTES WILL SUPPORT THE TRANSACTION SCOPE SPECIlED #HOOSE ALL THAT APPLY
R! 0 1HYHU
0 6XSSRUWV
0 5HTXLUHG
0 5HTXLUHV1HZ
d not be in a R. Method tr1 ibcoutule was Never E V E N ... ns ea m - Never n if its transaction at transactio
R" 0 5HTXLUHG
0 6XSSRUWV
0 0DQGDWRU\
0 5HTXLUHV1HZ
R# 0 5HTXLUHV1HZ
0 5HTXLUHV1HZ
0 6XSSRUWV
0 5HTXLUHV1HZ
R$ 0 5HTXLUHG
60
0 0DQGDWRU\
0 6XSSRUWV
0 6XSSRUWV
ion, but 1Õs transactan saction g in method be in nn tr ru w is ne 2 a d ho d - met RequiresNew, it woul d if it ha
- method 4 starts a does not have Supportsnew transaction, so it obviously as an attribute
(spec: 229)
'IVEN THE %*" 1, EXPRESSION SGLVFRXQW127%(7:((1$1' 7HICH EXPRESSION IS EQUIVALENT
- 10 and 15 ar e EXCLUDED
R! SGLVFRXQW 25SGLVFRXQW! R" SGLVFRXQW 25SGLVFRXQW! R# SGLVFRXQW 25SGLVFRXQW! R$ SGLVFRXQW 25SGLVFRXQW!
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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61
7HEN A BUSINESS METHOD IN AN ENTITY BEAN CALLS THE JHW5ROOEDFN2QO\ METHOD WHICH TRANSACTION ATTRIBUTE SETTINGS COULD CAUSE THE CONTAINER TO THROW AN EXCEPTION #HOOSE ALL THAT APPLY
(spec: 361)
R! .OT3UPPORTED R" 2EQUIRED R# 3UPPORTS - because there might not be one R$ 2EQUIRES.EW R% -ANDATORY R& .EVER
62
7HICH OF THE FOLLOWING IS PERFORMED BY THE CONTAINER IF A MESSAGE DRIVEN BEAN DOES NOT COMPLETE ITS TRANSACTION BEFORE THE END OF THE ON-ESSAGE METHOD #HOOSE ALL THAT APPLY
(spec: 356)
R! ,OG AN APPLICATION ERROR R" 2OLL BACK THE STARTED TRANSACTION R# $ISCARD THE INSTANCE OF THE BEAN R$ 4HROW AN EXCEPTION - to whom?
63
&ROM WHICH CLASSES CAN APPLICATION EXCEPTIONS EXTEND #HOOSE ALL THAT AP PLY
(spec: 373)
R! MDYDODQJ([FHSWLRQ R" MDYDODQJ5XQWLPH([FHSWLRQ - they must be checked R# MDYDUPL5HPRWH([FHSWLRQ - you just canÕt do this, even though it IS a checked exception... itÕs Bean Law R$ MDYD[HME&UHDWH([FHSWLRQ
64
7HATS TRUE ABOUT APPLICATION EXCEPTIONS #HOOSE ALL THAT APPLY
R! 4HEY ARE INTENDED TO BE HANDLED BY THE SYSTEM ADMINISTRATOR R" 4HEY SHOULD REPORT SYSTEM LEVEL PROBLEMS R# 4HEY CAUSE AUTOMATIC MARKING OF TRANSACTIONS FOR ROLLBACK R$ 4HEY MUST NOT EXTEND MDYDODQJ5XQWLPH([FHSWLRQ R% 4HEY MAY EXTENDMDYDUPL5HPRWH([FHSWLRQ - NO
(spec: 372-373) They are intended to be handled by the client
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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65
7HICH CASES CAN CAUSE A SESSION BEAN INSTANCE TO BE DESTROYED WITHOUT THE CONTAINER CALLING HME5HPRYH #HOOSE ALL THAT APPLY
(spec: 79)
R! ! TRANSACTION IS ROLLED BACK ON A STATEFUL SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCATION
R" ! SYSTEM EXCEPTION IS THROWN FROM A BUSINESS METHOD R# !N INACTIVE CLIENT IS TIMED OUT WHILE THE BEAN IS IN A PASSIVATED STATE R$ 4HE CLIENT INVOKES THE REMOVE METHOD WHILE THE BEAN IS IN A TRANSAC TION
66
- client gets exception, bean survives
7HICH DEPLOYMENT DESCRIPTOR ELEMENTS ARE USED TO SPECIFY A #OLLECTION INTERFACE #HOOSE ALL THAT APPLY
(spec: 462)
R! HMEQDPH! R" FPU¿HOG! R# HMEUHODWLRQ! multiplicity, to indicate R$ FPU¿HOGW\SH! - fororÒmanyÓ Set Collection R% DEVWUDFWVFKHPDQDPH!
67
)F A BEAN CATCHES A CHECKED EXCEPTION FROM WHICH IT CANNOT RECOVER WHAT SHOULD IT DO #HOOSE ALL THAT APPLY
(spec: 373)
R! )F THE CLIENT IS REMOTE THROW A MDYDUPL5HPRWH([FHSWLRQ - a bean must NEVER throw RemoteException. Only the R" 0RINT A STACK TRACE Container can do it. R# 2EGARDLESS OF THE CLIENT THROW A MDYD[HME(-%([FHSWLRQ R$ 2EGARDLESS OF THE CLIENT PROPAGATE THE SAME EXCEPTION TO THE CONTAIN ER
68
7HICH ARE REQUIREMENTS FOR A #-0 ENTITY BEAN CLASS #HOOSE ALL THAT APPLY
(spec: 190-191)
R! !LL HME6HOHFW METHODS MUST BE DECLARED AS ABSTRACT R" 4HE CLASS MUST ./4 DElNE AN HME&UHDWH METHOD R# 4HE HME3RVW&UHDWH METHODS ARE IMPLEMENTED BY THE CONTAINER R$ (ELPER METHODS MUST ./4 BE IMPLEMENTED IN THE BEAN CLASS R% -ETHODS STARTING WITH @HME)LQG MUST NOT BE IMPLEMENTED
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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PRFNH[DPDQVZHUV
69
7HICH ARE VALID DEPLOYMENT DESCRIPTOR SEGMENTS TO DElNE A CMR lELD #HOOSE ALL THAT APPLY
(spec: 162, 463)
R! HMEUHODWLRQVKLSUROH!
DVVXPHPDQGDWRU\HMEUHODWLRQVKLSUROHHOHPHQWV LQVHUWHGKHUH!
FPU¿HOG!
FPU¿HOG!
FPU¿HOGW\SH!MDYDXWLO&ROOHFWLRQ FPU¿HOGW\SH!
me
-missing Þeld na
HMEUHODWLRQVKLSUROH!
R" HMEUHODWLRQVKLSUROH!
DVVXPHPDQGDWRU\HMEUHODWLRQVKLSUROHHOHPHQWV LQVHUWHGKHUH!
FPU¿HOG!
FPU¿HOGQDPH!OLQH,WHPV FPU¿HOGQDPH!
FPU¿HOGW\SH!MDYDXWLO&ROOHFWLRQ FPU¿HOGW\SH!
FPU¿HOG!
HMEUHODWLRQVKLSUROH!
R# UHODWLRQVKLSUROHVRXUFH!
DVVXPHPDQGDWRU\UHODWLRQVKLSUROHVRXUFHHOH PHQWVLQVHUWHGKHUH!
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FPU¿HOG!
FPU¿HOGW\SH!MDYDXWLO&ROOHFWLRQ FPU¿HOGW\SH!
- missing name, and in role source, as opposed to role
UHODWLRQVKLSUROHVRXUFH!
R$ UHODWLRQVKLSUROHVRXUFH!
DVVXPHPDQGDWRU\UHODWLRQVKLSUROHVRXUFHHOH PHQWVLQVHUWHGKHUH!
FPU¿HOG!
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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DSSHQGL[$ILQDOPRFNH[DP
70
(spec: 383)
7HATS TRUE ABOUT A REMOTE CLIENTS VIEW OF EXCEPTIONS RECEIVED FROM AN ENTITY BEAN #HOOSE ALL THAT APPLY
R! )F THE CONTAINER MARKS A TRANSACTION FOR ROLLBACK THE CONTAINER WILL ALWAYS ISSUE A MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5ROOHGEDFN([FH SWLRQ EXCEPTION
R" )F THE CLIENT RECEIVES A MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5ROOHG
- only if the callerÕs transaction was rolled back (as opposed to suspended)
%DFN([FHSWLRQ THE CONTAINER GUARANTEES THAT THAT TRANSACTION WILL NEVER COMMIT
the
happens with R# ! MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5HTXLUHG([FHSWLRQ EXCEP -Mandator y tx attribute TION INFORMS THE CLIENT THAT THE BEAN NEEDED TO BE CALLED WITHIN THE CONTEXT OF A TRANSACTION
R$ )F THE CONTAINER DISCOVERS THAT A REQUESTED BEAN NO LONGER EXISTS IT WILL ALWAYS THROW THE MDYD[HME1R6XFK2EMHFW(QWLW\([FHSWLRQ
- java.rmi.NoS
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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This isnÕt goodbye 'RQ·W\RXNQRZWKHUH·VPRUHRQWKH
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
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We were the wholethhainndking this might play up do you think? s-on approach... wha t -K & B
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Hey, is this what you had in mind by Òemphasize the Head?Ó -K&B >XPQRPDUNHWLQJ@
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\ WasnÕt this the one we agreed on last week? - K & B
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Appendix A. Final Mock Exam Head First EJB™ By Bert Bates, Kathy Sierra ISBN: 0596005717 Publisher: O'Reilly Prepared for Linda Martin, Safari ID: [email protected] Print Publication Date: 2003/10/01 User number: 896963 Copyright 2008, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.
