Head First EJB™ by Kathy Sierra and Bert Bates Copyright © 2003 O’Reilly Media, Inc. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (safari.oreilly.com). For more information, contact our corporate/institutional sales department: (800) 998-9938 or
[email protected]. Editor:
Mike Loukides
Cover Designer:
Edie Freedman
Interior Decorators: Kathy Sierra and Bert Bates Anthropomorphizer: Bert Bates Bean Wrangler:
Kathy Sierra
Printing History: October 2003: First Edition.
The O’Reilly logo is a registered trademark of O’Reilly Media, Inc. Java and all Java-based trademarks and logos are trademarks or registered trademarks of Sun Microsystems, Inc., in the United States and other countries. O’Reilly Media, Inc. is independent of Sun Microsystems. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and O’Reilly was aware of a trademark claim, the designations have been printed in caps or initial caps. While every precaution has been taken in the preparation of this book, the publisher and the authors assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. In other words, if you use anything in Head First EJB™ to, say, run a nuclear power plant or air traffic control system, you’re on your own. And although some people have been able to pass the exam simply by placing this book under their pillow each night for three consecutive weeks, we generally don’t recommend it. Most people find it helpful to actually read the book or at least look at the pictures. ISBN-10: 0-596-00571-7 ISBN-13: 978-0-596-00571-9 [M]
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Table of Contents (summary) Intro
xix
1
Welcome to EJB: an introduction
1
2
EJB Architecture: architectural overview
3
Exposing Yourself: the client view
111
4
Being a Session Bean: session bean lifecycle
173
5
Entities are Persistent: entity bean intro
259
6
Being an Entity Bean: bean/entity synchronization
295
7
When Beans Relate: entity bean relationships
373
8
Getting the Message: message-driven beans
437
9
The Atomic Age: EJB transactions
469
10
When Beans Go Bad: exceptions in EJB
525
11
Protect Your Secrets: security in EJB
569
12
The Joy of Deployment: a bean’s environment
599
A
Appendix A: Final Mock Exam
637
61
Table of Contents (the real thing)
i
Intro Your brain on EJB.
Here you are trying to learn something, while here your brain
is doing you a favor by making sure the learning doesn’t stick. Your brain’s thinking, “Better leave room for more important things, like which wild animals to avoid and whether naked snowboarding is a bad idea.” So how do you trick your brain into thinking that your life depends on knowing EJB? Who is this book for?
xviii
We know what your brain is thinking
xix
Metacognition
xxi
Bend your brain into submission
xxiii
What you need for this book
xxiv
Passing the certification exam
xxvi
Technical reviewers
xxviii
Acknowledgements
xxix
ix
1
Welcome to EJB Enterprise JavaBeans are easy. Well, at least when you compare EJB to what you’d have to do to write your own scalable, transactional, secure, persistent, concurrent enterprise component server. In this chapter, we’ll develop, deploy, and run an EJB application, and then dive into the details. Before we’re done, we’ll look at the use, benefits, and characteristics of EJB, and we’ll look (briefly) at how EJB containers work.
t EJB obj e c
En
an
services
biz interface
Server
terp se be ri
EJB Container
biz logic separate from data DB
2
Exam objectives
2
What is EJB all about?
3
No more vendor lock-in!
5
How does it all work?
7
Behind the scenes...
8
Beans come in three flavors
11
The Advice Guy bean
15
Five things you do to build a bean
16
EJB Roles and Responsibilities
26
Tutorial
28
Coffee Cram
59
EJB Architecture EJB is about infrastructure. Your components are the building blocks. With EJB, you can build big applications. The kind of applications that could run everything from the Victoria’s Secret back-end to document-handling systems at CERN. But an architecture with this much flexibility, power, and scalability isn’t simple. It all begins with a distributed programming model...
(J2SE API)
<
> Remote
(J2EE API)
no methods
no methods
(J2EE API)
<> EJBObject // several methods
YOU write this interface (the remote component interface)
<> BookCart addBook() removeBook() showBooksInCart() doCheckout()
<> EnterpriseBean
(J2EE API)
<> SessionBean // several methods
BookCartBean
YOU write this class addBook() removeBook() (the bean class) showBooksInCart() doCheckout() // other methods
x
Exam objectives
62
Making a Remote method call
64
What about arguments and return values?
67
The client calls business methods through the Remote interface
79
EJB uses RMI
81
The Remote object is not the bean, it’s the bean’s bodyguard
82
Architectural overview: Session beans
98
Architectural overview: Entity beans
99
Architectural overview: Creating a Stateful Session bean
100
Architectural overview: Creating a Stateless Session bean
101
Architectural overview: Message-driven beans
106
Organize your beans
108
3
Exposing Yourself You can’t keep your bean private. Clients need to see what you’ve got. (Except for message-driven beans, which don’t have a client view). The Advice Bean exposes the getAdvice() method in its Component interface—the place where you declare business methods. But that’s not all the client sees. Remember, the Advice interface extends EJBObject, an interface with methods of its own. Methods the client can see. Methods the client can call. And it works the same way with the Home interface.
Stateless beans
These beans are all identical
bean
bean bean
For stateless session beans from the same home, isIdentical() always returns true, even for different beans.
4
Exam objectives
112
What the client really wants
113
What’s JNDI?
116
PortableRemoteObject.narrow() (exotic casting)
121
Writing the Remote home interface for a session bean
125
Thankfully, we’ve got handles (online shopping takes time)
139
Which methods make sense for the local client interfaces?
148
Why so many remove methods?
151
Comparing Remote vs. Local interfaces
154
Arguments to Remote vs. local methods
163
Coffee Cram
168
Being a Session Bean Session beans are created and removed. If you’re lucky, you’re a stateless bean. Because the life of a stateful bean is tied to the whims of a heartless client. Stateful beans are created at the client’s insistence, and live and die only to serve that one client. But ahhhh, the life of a stateless bean is fabulous! Pools, those little umbrella drinks, and no boredom since you get to meet so many different clients.
For me? This is such a special moment! Once in a lifetime...
Exam objectives
174
Container callbacks, for the special moments in a bean’s life
181
Bean Creation
188
Bean things you can do within business methods
199
Passivation: a stateful bean’s chance at scalability
200
Bean Removal
208
Writing a Session Bean: your job as Bean Provider
230
SessionContext: you need it more than it needs you
240
Coffee Cram
244
xi
5
Entities are Persistent Entity beans persist. Entity beans exist. Entity beans are. They are object representations of something in an underlying persistent store. (Think: database, because most entity beans represent something from a relational database.) If you have a Customer entity bean, then one bean might represent the entity Tyler Durden, ID #343,
If you’ve got any last words, you better do it in your ejbRemove()...
while another is the entity Donny Darko, ID #42. Three beans, representing three real entities. An entity bean is simply a realization of something that already exists.
No, Please, No! I’ll give you whatever you want, just don’t call remove()!
6 If I’m a bean I say to a method, “Don’t call me, call my bodyguard, and here’s his contact information...”
Instead of:
260
What’s an entity bean?
261
Entity beans from the client’s point of view
265
A very simple Customer entity bean
268
Entity bean Remote component interface
270
Entity bean Remote home interface
273
What does the client really want from an entity bean home?
274
Home business methods to the rescue
278
Session bean create() vs. entity bean create()
281
Session bean remove() vs. entity bean remove()
282
Entity/bean/instance death
285
Coffee Cram
288
Being an Entity Bean Entity beans are actors. As long as they’re alive, they’re either in the pool or they’re being somebody. Somebody from the underlying persistent store (an entity from the database). When a bean is playing a part, the bean and the underlying entity have to stay in sync. Imagine the horror if the bean is pretending to be, say, Audrey Leone, and someone lowers Audrey’s credit limit in the database... but forgets to tell the bean.
bean
doStuff(this); EJB object
Use: doStuff(myContext.getEJBObject());
xii
Exam objectives
Exam objectives
296
The real power of entity beans is synchronization
298
Container-managed vs. bean-managed persistence
303
The EntityBean interface adds new container callbacks
310
Writing a CMP entity bean
313
Object identity: the primary key
332
Finder methods
339
Home business methods
345
Coffee Cram
362
7
When Beans Relate Entity beans need relationships. An Order needs a Customer. A LineItem needs an Order. An Order needs LineItems. Entity beans can have container-managed relationships (CMR) and the Container takes care of virtually everything. Make a new LineItem that’s related to an Order? If you ask the Customer to show you his Orders, you’ll see the new LineItem. Best of all, you can use EJB-QL to write portable queries.
Multiplicity: many
Multiplicity: one Director
Movie
Collection getMovies()
Director getDirector()
0..*
1
one Director. Each Movie has y Movies. man A Director has
8 <> EJBContext
getCallerPrincipal() getEJBHome() isCallerInRole(String s) getRollbackOnly() getEJBLocalHome() getUserTransaction() setRollbackOnly()
<> MessageDrivenContext
Exam objectives
374
Relationships
378
Multiplicity
380
CMP and CMR fields
383
Cascade delete can propagate
393
EJB-QL for the MovieBean
402
SELECT and FROM are the mandatory!
409
The WHERE clause
411
Collections don’t bark()!
414
The BETWEEN, IN, IS EMPTY, and LIKE expression
416
Relationship assignments
421
Coffee cram
425
Getting the Message It’s fun to receive messages. Not as much fun as, say, getting that eBay package with the genuine Smurf™ lamp, but fun and efficient nonetheless. Imagine if you sent your order to eBay, and you couldn’t leave your house until the package was delivered. That’s what it’s like with Session and Entity beans. But with message-driven beans, the client can send a message and walk away.
My life is sad. I have no home, I have no clients... I can use my context ONLY for transactions... Oh well, at least I get a pool.
Exam objectives
438
Writing a message-driven bean: your job as Bean Provider
447
Complete DD for a message-driven bean
449
Topics and Queues
450
MessageDrivenContext
455
Message acknowledgement
458
Coffee Cram
463
// this interface adds no // new methods
xiii
9
The Atomic Age Transactions protect you. With transactions, you can try something knowing that if anything goes wrong along the way, you can just pretend the whole thing didn’t happen. Everything goes back to the way it was before. Transactions in EJB are a thing of beauty—you can deploy a bean with customized transaction behavior without touching the bean’s source code! But you can write transaction code, if you need to.
������������� CMT beans ru n transactions unknown, while BMT be ans use only their own. OK, not our be st work, we kn ow. So why don’t you tr y it. Memor y de vices can help, but they work much be tter when you create th em yourself.
10
Oh sh**! A system exception. Nothing I can do about it. There goes my stateful bean. I’ll have to start over...
Exam objectives
470
The ACID test
472
How it works in EJB
474
Transaction propagation
475
How do I make (or get) a transaction?
476
setRollbackOnly() lives in TWO interfaces
487
BMT can be a really BAD idea.
490
BMT hurts bean reuse
Container-managed transactions
491
How attributes work
492
Methods you MUST mark with an attribute (for a CMT bean)
498
“Unspecified Transaction Context”
499
DD example for CMT
503
SessionSynchronization “special moments”
512
Coffee cram
516
When Beans Go Bad Expect the unexpected. Despite your best efforts, things can go wrong. Terribly, tragically, wrong. You need to protect yourself. You can’t let your entire program collapse, just because one bean in the family throws an exception. The application must go on. You can’t prevent tragedy, but you can prepare for it. You need to know what is and is not recoverable, and who is responsible when a problem occurs.
Gotta love application exceptions... I can recover from this if I put in a different value for the argument to the create() method...
xiv
Exam objectives
526
In EJB, exceptions come in two flavors
532
With an Application Exception, the Container will...
533
With a System Exception, the Container will...
534
RemoteException vs. EJBException
539
Bean Provider’s responsibilities
541
The five standard EJB application exceptions
548
Common system exceptions
551
Coffee cram
563
11
Protect Your Secrets Keep your secrets. Security is about authentication and authorization. First, you have to prove your identity, and then we’ll tell you what you’re allowed to do. Security is easy in EJB, because you’re only dealing with authorization. You decide who gets to call which methods on your beans. Except one problem... if you’re a Bean Provider or App Assembler, you probably don’t know who the users are going to be! In a vendorspecific way
In the EJB Deployment Descriptor
users and groups
In a companyspecific way
real people
Exam objectives
570
How to do security in EJB
573
The Application Assembler’s job: access control
574
Defining the method permissions
578
The Deployer’s job: mapping actual humans to abstract roles 583
12
Class-level vs. instance-level security
586
Using programmatic security to custom-tailor a method
587
Use security identity to pretend someone else is calling...
591
Security context propagation with
592
Coffee cram
593
The Joy of Deployment You worked hard on that bean. You coded, you compiled, you tested. About a hundred zillion times. The last thing you want to touch is already-tested source code, just because something simple changed in the deployment configuration. And what if you don’t even have the source code? EJB supports bean reuse through the customizable Deployment Descriptor and a bean’s special environment.
JAR 1
ejb-jar META-INF
com
headfirst
ejb-jar.xml 011 0 1 1100 1 0 100 0 0 1 1 1 0111 0 11 00011 01
011 0 1 1100 1 0 100 0 0 1 1 1 0111 0 11 00011 01
011 0 1 1100 1 0 100 0 0 1 1 1 0111 0 11 00011 01
AdviceBean.class
Advice.class AdviceHome.class
Exam objectives
600
A bean’s special place- java:comp/env
602
Creating and using a subcontext
609
Bean Provider and Application Assembler responsibility
617
Deployer responsibility
618
Remembering who does what
619
Which APIs does EJB 2.0 guarantee?
621
What MUST be in an ejb-jar?
624
Programming restrictions
625
Coffee cram
627
xv
A
Appendix A
The final Coffee Cram Mock Exam. This is it.
70 questions. The tone, topics,
and difficulty level are virtually identical to the real exam. We know. Final Mock Exam
i
xvi
Index
637
685
Intro to EJB
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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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A:
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
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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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(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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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
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,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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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$SSOLFDWLRQ
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.O 7ITH A *%% SERVER THE WEB COMPONENTS AND %*" COMPONENTS ARE MORE TIGHTLY INTEGRATED WHICH MEANS YOU CAN HAVE ALL OF THE COMPONENTS RESPECT ONE ANOTHERS TRANSAC TIONS AND SECURITY "UT YOURE ALWAYS FREE TO USE A SERVLET AS A CLIENT TO AN ENTERPRISE BEAN EVEN IF THAT BEAN ISNT RUNNING IN THE SAME APPLICATION SERVER OR EVEN THE SAME PHYSICAL MACHINE !NOTHER ADVANTAGE OF A *%% SERVER IS THE EASE WITH WHICH YOU CAN DEPLOY BOTH COMPONENT TYPES AS PART OF ONE ENTERPRISE APPLICATION (AVING SAID ALL THIS CHANCES ARE EXTREMELY HIGH THAT IF YOURE DO ING %*" APPLICATIONS YOU ARE RUNNING THEM IN A *%% SERVER 2EMEMBER THERE ARE VERY FEW STANDALONE %*" CONTAINERS TODAY 6IRTUALLY ALL SIGNIFICANT VENDORS RUN THEIR %*" CONTAINERS WITHIN A *%% SERVER
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6IUMIVL[I^M\PMVM_IXXTQKI\QWV 4HIS PARTS A LITTLE AWKWARD 9OU CAN USE THE "ROWSE BUTTON TO NAVIGATE THROUGH YOUR OWN DIRECTORY TREE BUT THE EASIEST WAY TO NAME AND SAVE THE APPLICATION IS TO TYPE THE COMPLETE PATH TO THE lLE YOURE ABOUT TO CREATE 4HE THING WERE MAKING IS NOT THE BEAN ITSELFYOU CAN THINK OF IT MORE LIKE A DOCUMENT THAT HOLDS ALL THE INFORMATION ABOUT THE APPLICATION !S A CONVENTION WE SAVE THE APPLICATION IN THE PROJECTS;WHATEVER= DIRECTORYTHE DIRECTORY CORRESPONDING TO THAT PARTICULAR PROJECT &OR THE !DVICE BEAN THAT MEANS THE PROJECTS ADVICE DIRECTORY )F YOU STARTED THE SERVER FROM THE PROJECTSADVICE DIRECTORY IN OTHER WORDS IF ADVICE IS YOUR CURRENT WORKING DIRECTORY THEN YOULL GET THE RIGHT NAME AND LOCATION BY DEFAULT 1DPHWKHDSSOLFDWLRQ$GYLFH$SS ,IQHHGHGLQFOXGHWKHIXOOSDWKWRSURMHFWVDGYLFH$GYLFH$SS &OLFN2.
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6W__M¼ZMQV\PMZMITTaKWWT 6M_-V\MZXZQ[M*MIV?QbIZL 4HIS PART OF THE DEPLOYTOOL IS WHERE ALMOST EVERYTHING HAPPENS 4HE KEY THINGS WELL DO ARE 5 #REATE THE EJB JAR 5 0UT THE BEAN CLASS AND THE TWO INTERFACES INTO THE EJB JAR 5 #REATE THE DEPLOYMENT DESCRIPTOR THAT DESCRIBES THE BEAN
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+ZMI\M\PMVM_MRJRIZ &OR NOW JUST ACCEPT THE DEFAULTS 4HE RADIO BUTTON ON THE TOP LEFT OF THE SCREEN SHOWS THAT YOURE MAKING A NEW *!2 WITHIN THE !DVICE!PP APPLICATION .OTICE THAT THE !DVICE!PP IS PART OF A DROP DOWN LISTIF THERE WERE OTHER EJB JARS ALREADY IN THE APPLICATION WE COULD HAVE CHOSEN TO PUT THE NEW BEAN IN A PRE EXISTING *!2 4HE TOOL PICKS AN ESPECIALLY HELPFUL DISPLAY NAME h%JBv AND YOULL SEE THIS BACK ON THE MAIN DEPLOYTOOL SCREEN WHEN WERE DONE 4HAT NAME ISNT USED ANYWHERE IN YOUR REAL APPLICATION SO ITS NO BIG DEAL BUT IF YOU HAVE MORE THAN ONE *!2 IN AN APPLICATION YOU MIGHT WANT TO GIVE IT A MORE DESCRIPTIVE NAME #ART *!2 !CCOUNT *!2 ETC
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)LL\PM\PZMMKTI[[NQTM[QVKT]LQVO\PMQZ XIKSIOMLQZMK\WZa\W\PM2): 4HIS IS THE MOST IMPORTANT PART OF THE WHOLE PROCESS )N OTHER WORDS DONT SCREW IT UP 4HE KEY IS TO GET THE CORRECT CLASSES INTO THE *!2 IN THEIR PACKAGE DIRECTORY STRUCTURE AND ONLY THEIR PACKAGE DIRECTORY STRUCTURE )N OTHER WORDS IF YOU PUT THE THREE CLASS lLES INTO THE *!2 WITHOUT THE HEADlRST DIRECTORY YOUR BEAN WONT DEPLOY /R IF YOU INCLUDE THE CLASSES DIRECTORY AS WELL AS THE HEADlRST DIRECTORY YOUR BEANS WONT DEPLOY 2EMEMBER THE EJB JAR IS STILL A *!2 lLE SO THE USUAL *!2 RULES ABOUT PACKAGE STRUCTURES APPLY HERE 1DYLJDWHWRWKH$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 direc rie s. Then select the headto Þr st directory. You donÕt to expand it... we didhave it so that you could see whatÕs in there.
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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
DonÕt click the Next button!! We have way more to do on this screen .
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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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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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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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:]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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+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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?PM_ 6WNIQTML\M[\[ )F EVERYTHING VERIlES YOU SEE A NICE LITTLE MESSAGE IN THE $ETAILS BOX AT THE BOTTOM OF THE VERIlER WINDOW )F THERE ARE FAILURES YOULL SEE THEM IN THE 2ESULTS BOX 9OU CAN CLICK ON A @FAILURE MESSAGE TO GET MORE DETAILS ABOUT WHAT WENT WRONG $ONT PANIC IF YOU SEE A MILLION FAILURES USUALLY YOU CAN lX ONE THING AND THEY ALL GO AWAY 5NLIKE COMPILER ERROR MESSAGES WHICH ARE SOMETIMES ABOUT AS HELPFUL AS 6#2 INSTRUCTIONS THE VERIlER FAILURE MESSAGES ARE PRETTY EXPLICIT 9OU CAN USUALLY lGURE OUT EXACTLY WHERE YOU WENT WRONG 3OMETIMES YOU CAN lX THE PROBLEM BACK IN THE MAIN DEPLOYTOOL WINDOW BY CLICKING ON ONE OF THE TABBED PANELS AND CHANGING SOMETHING &OR EXAMPLE IF YOU FORGOT TO SPECIFY A TRANSACTION ATTRIBUTE FOR AN ENTITY BEAN METHOD YOU CAN GO TO THE 4RANSACTIONS TABBED PANEL IN THE DEPLOYTOOL WINDOW AND SET THE ATTRIBUTE WITHOUT STARTING OVER IN THE BEAN WIZARD "UT IF YOU HAVE PROBLEMS WITH YOUR ACTUAL CLASS lLES YOULL HAVE TO MODIFY THEM RECOMPILE THEM AND THEN UPDATE YOUR EJB JAR /R IF THE PROBLEM IS THAT YOU MADE A SETTING IN THE BEAN WIZARD THAT CANT BE CHANGED LIKE SELECTING THE BEAN CLASS WHEN THE TOOL ASKS FOR THE HOME INTERFACE YOULL HAVE TO DELETE THE EJB JAR AND START OVER WITH THE BEAN WIZARD %HKDSS\DERXWWKHZRQGHUIXOPHVVDJHDWWKHERWWRP &OLFN&ORVH
Click Close to put away the window. If you click OK, youÕll just run the veriÞer again.
4O UPDATE YOUR EJB JAR lLE CHOOSE THE @4OOLS THEN @5PDATE &ILES MENU OPTIONS
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5ISMQ\:M\]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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/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$GYLVRU &OLFN)LQLVK 7DNHDGHHSEUHDWKDQGKROGLWXQWLOWKHGHSOR\SURFHVVFRPSOHWHV
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?I\KP\PMXZWOZM[[JIZ[OW]X\PMVKMTMJZI\M 7AIT FOR IT WAIT FOR IT WAIT FOR IT 7HEN THE BEANS DEPLOYED SUCCESSFULLY YOULL SEE THE LINE h$EPLOYMENT OF !DVICE!PP IS COMPLETEv IN THE WINDOW !T THAT POINT CLIENTS CAN ACCESS THE BEAN 9OU DID IT &OLFN2.
ItÕs a miracle ! It worked !
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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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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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&OR A DISTRIBUTED PROGRAMMING MODEL THATS A PRETTY PERMANENT DECISION WITH NO CHANCE TO CHANGE YOUR MIND LATER WITHOUT REWRITING CODE /N THE OTHER HAND IF YOU DO USE 2-) YOU CAN DECIDE LATER TO SPLIT YOUR PROGRAM UP INTO DIFFERENT NODES ON YOUR SYSTEM WITH LITTLE OR USUALLY NO CODE CHANGES
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3O THE TRADEOFF IS FLEXIBILITY FOR PERFORMANCE BUT FOR MOST DISTRIBUTED ENTERPRISE APPS THE OVERHEAD OF A REMOTE CALL IS NOT YOUR BIGGEST PROBLEM )TS USUALLY YOUR BANDWIDTH ANDOR CONCURRENCY THAT HURTS THE MOST /VERALL YOU PROBABLY HAVE BIGGER PERFORMANCE FISH TO FRY IN AREAS OTHER THAN WHETHER YOUR CALLS ARE REMOTE OR LOCAL "UT THE STORY ISNT ALWAYS THAT SIMPLE SO WELL EXPLORE THIS AGAIN LATER IN THE BOOK
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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
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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
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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:
7HEN ARE WE GOING TO TALK ABOUT THE (OME
A: Q:
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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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?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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Dumb Questions
Q:
(ERES SOMETHING THAT IS 2%!,,9 STARTING TO ANNOY ME WHY DO YOU HAVE A #OMPONENT INTERFACE AND A (OME INTERFACE WHEN THE 2EMOTE OBJECTS ARE CALLED THE (OME AND THE %*"/BJECT 7HY ISNT IT JUST THE %*"/BJECT INTERFACE AND THE (OME/BJECT INTERFACE /R THE (OME AND THE %*" INTERFACES 7HY THE INCONSISTENCY
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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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Dumb Questions
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(OW DOES THIS WORK )S THERE ONE BEAN POOL FOR ALL BEANS OR ONE BEAN POOL FOR A PARTICULAR TYPE OF BEAN
A:
)N REALITY WE DONT KNOW WHAT THE CONTAINER IMPLEMENTATION IS BUT CONCEPTUALLY THERES ONE POOL FOR EVERY BEAN TYPE 3O IF YOU DEPLOY AN !DVICE"EAN AND A 7EATHER"EAN AND BOTH ARE STATELESS SESSION BEANS THEYLL EACH GET THEIR OWN POOL
Q:
$OES EACH STATELESS SESSION BEAN HAVE ITS OWN %*"/BJECT
A:
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
Q:
7HY DONT STATEFUL SESSION BEANS HAVE A POOL
A:
(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
Q:
(OW LONG DOES A STATEFUL BEAN KEEP CLIENT SPECIlC STATE
A:
/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
Q:
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The client sends a message to a JMS messaging service.
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?PI\\PMKTQMV\ZMITTa_IV\[ 4HE CLIENT HAS A GOAL ! VISION ! QUEST 3HE WANTS TO CALL A BUSINESS METHOD ON THE BEAN 3OMETHING EXPOSED IN THE COMPONENT INTERFACE .EVER FORGET THAT ULTIMATE GOAL IT IS EASY TO GET BOGGED DOWN IN ALL THE DETAILS "UT IF YOU KEEP FOCUSED ON THE CLIENTS DRIVING NEED YOULL HAVE A MUCH EASIER TIME REMEMBERING THINGS LIKE SAY THE RETURN TYPE OF A SESSION BEANS HOME CREATE METHOD
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1\ITT[\IZ\[_Q\P\PMPWUMQV\MZNIKM 4HE CLIENT WANTS THE BEAN 7ELL TOO BAD 4HE CLIENT WILL NEVER GET THE BEAN BECAUSE NOBODY TALKS TO THE BEAN EXCEPT THE CONTAINER 4HE BEST THE CLIENT CAN HOPE FOR IS A REFERENCE TO THE BEANS BODYGUARDTHE COMPONENT INTERFACE !ND THE CLIENT GETS A REFERENCE TO THE BEANS COMPONENT INTERFACE BY CALLING A METHOD ON THE BEANS HOME INTERFACE
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(OW COME YOU SAID h!ND THE CLIENT GETS A REFERENCE TO THE BEANS COMPONENT INTERFACEv 9OU CANT HAVE A REFERENCE TO AN INTERFACE IN *AVAYOU CAN REFERENCE AN OBJECT BUT YOU CANT REFERENCE AN INTERFACE 4HE REFERENCE VARIABLE CAN BE DECLARED AS AN INTERFACE TYPE BUT THATS NOT THE SAME THING
A:
7ELL ACTUALLY IT IS THE SAME THING )N THIS BOOK AND IN THE SPEC AND IN THE EXAM EVERYWHERE YOU SEE THE PHRASE hREFERENCE TO AN INTERFACEv DO A MENTAL SEARCH AND REPLACE TO MAKE IT hREFERENCE TO AN OBJECT THAT IMPLEMENTS THE INTERFACEv )T CAN FEEL A LITTLE STRANGE IF YOU HAVENT READ DOCUMENTS THAT USE THIS CONVENTION BUT YOU BETTER GET USED TO IT "UT DONT WORRY BY #HAPTER YOULL WONDER HOW ANYONE EVER SAID IT DIFFERENTLY
Q:
9OU SAID THE CLIENTS ULTIMATE GOAL IS TO CALL METHODS ON THE BEAN /+ THE COMPONENT INTERFACE BUT YOU KNOW WHAT ) MEAN "UT WITH ENTITY BEANS YOU CAN HAVE BUSINESS METHODS IN THE HOME RIGHT 3O WITH ENTITY BEANS ISNT IT TRUE THAT SOMETIMES THE CLIENTS GOAL IS *534 TO USE THE HOME
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9ES YOURE RIGHT 4HEYRE CALLED hHOME BUSINESS METHODSv AS OPPOSED TO PLAIN OLD hHOME METHODSv OR PLAIN OLD hBUSINESS METHODSv "UT THEYRE A SPECIAL CASE WELL LOOK AT LATER IN THE BOOK 4HERE ARE OTHER REASONS TOO FOR WHY YOU MIGHT NEED ONLY THE HOME OF AN ENTITY BEAN &OR EXAMPLE IF YOU WANT TO CREATE A BUNCH OF NEW CUSTOMERS IN A DATABASE BUT YOU DONT WANT TO DO ANY OTHER OPERATIONS ON REFERENCES TO THOSE ENTITY CUSTOMERS
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?PI\¼[26,1' *.$) STANDS FOR *AVA .AMING AND $IRECTORY )NTERFACE AND ITS AN !0) FOR ACCESSING NAMING AND DIRECTORY SERVICES !LTHOUGH *.$) IS QUITE POWERFUL THERE ARE ONLY A FEW PIECES OF IT YOU NEED TO KNOW FOR %*"HOW CLIENTS lND IT HOW CLIENTS USE IT HOW BEANS USE IT AND HOW TO PUT THINGS INTO IT 4HE *.$) !0) CAN WORK WITH MANY DIFFERENT SERVICES AS LONG AS THAT REM SERVICE HAS A *.$) DRIVER CALLED A 3ERVICE 0ROVIDER )TS A LOT LIKE *$"# WHERE YOU THE DEVELOPER USE THE *$"# !0) TO SEND 31, STATEMENTS TO A VARIETY OF DIFFERENT DATABASES 4HE *.$) DRIVER TRANSLATES THE METHOD CALLS YOU MAKE ON THE *.$) !0) INTO SOMETHING THE UNDERLYING NAMINGDIRECTORY SERVICE UNDERSTANDS
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7ERE CHEATING A LITTLE BECAUSE THE CODE WERE USING WORKS ONLY BECAUSE WERE USING THE 2EFERENCE )MPLEMENTATION AND EVEN THEN ONLY BECAUSE WERE RUNNING THE SERVER ON THE SAME PHYSICAL MACHINE AS THE CLIENT 3O WERE TAKING ADVANTAGE OF DEFAULT SETTINGS THAT ARE IN PLACE AUTOMATICALLY BECAUSE WERE RUNNING THE 2EFERENCE )MPLEMENTATION
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7E LIED A LITTLE IN POINT NUMBER ABOVE BECAUSE THIS CODE COULD BE CORRECT IF IT WERE INSIDE A BEAN 7ELL GET TO THAT IN THE "EAN %NVIRONMENT CHAPTER
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A:
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A:
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A:
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Q:
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:
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Q:
7HY CANT YOU SERIALIZE THE STUB 7HY DO WE NEED HANDLES
A:
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Q: A:
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,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
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,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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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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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
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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:
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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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7HICH CAPABILITIES ARE PROVIDED BY BOTH REMOTE AND LOCAL HOME INTERFACES FOR SESSION BEANS #HOOSE ALL THAT APPLY
R! #REATING A SESSION OBJECT R" 2EMOVING A SESSION OBJECT R# 'ETTING A SESSION OBJECTS %*"-ETA$ATA R$ 'ETTING A SESSION OBJECTS HANDLE
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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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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session beanlos cacal home interface becausye ket y R! #REATING A SESSION OBJECT through a ove() that takes a primar a rem R" 2EMOVING A SESSION OBJECT - only R# 'ETTING A SESSION OBJECTS %*"-ETA$ATA - not in a local home R$ 'ETTING A SESSION OBJECTS HANDLE - not in a local home
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
is
(spec: 57)
R! 4HE SESSION CONTEXT MUST BE NARROWED AND THE NARROWED RESULT CAST R" 4HE RESULT OF THE *.$) LOOKUP MUST BE NARROWED AND THE NARROWED RESULT CAST
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3
'IVEN A REMOTE CLIENT @2 THAT HAS VALID REFERENCES TO SESSION BEANS @! AND @" AND GIVEN THAT ! IS A LOCAL CLIENT TO " WHICH STATEMENTS ARE TRUE #HOOSE ALL THAT APPLY
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7HEN COMPARING TWO SESSION OBJECTS WHAT IS TRUE #HOOSE ALL THAT APPLY
(spec: 65-66)
R! 5SING THE IS)DENTICAL METHOD STATELESS SESSION BEANS FROM THE SAME HOME WILL ALWAYS RETURN TRUE
R" 5SING THE IS)DENTICAL METHOD STATEFUL SESSION BEANS FROM THE SAME HOME WILL ALWAYS RETURN TRUE
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of R$ 5SING THE EQUALS METHOD STATELESS SESSION BEANS FROM THE SAME HOME The behavior iÞed
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ARE GUARANTEED TO RETURN TRUE
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7HICH STATEMENTS ABOUT SESSION BEANS ARE TRUE #HOOSE ALL THAT APPLY
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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 )$% THAT PUTS THE METHODS IN FOR YOU ANYWAY 3TILL IT MIGHT BE HANDY TO MAKE YOURSELF A GENERIC BEAN THAT YOU TYPICALLY EXTEND FROM THAT HAS ALL OF THE METHODS FROM 3ESSION"EAN 7ITH STATELESS BEANS ESPECIALLY YOU HAVE TO IMPLEMENT EJB!CTIVATE AND EJB0ASSIVATE EVEN THOUGH THEYLL NEVER BE CALLED 3TATELESS BEANS ARE NEVER PASSIVATED YOULL SEE MORE ON THAT LATER IN THE CHAPTER
Q:
) JUST REMEMBERED THAT ) READ SOMEWHERE THAT ENTERPRISE BEANS DONT SUPPORT INHERITANCE 7HATS THAT ABOUT
A:
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7HY DO YOU CARE ABOUT CREATION DETAILS "ECAUSE SOMEWHERE BETWEEN THE CONSTRUCTOR AND THE CREATE METHOD THE BEAN IS IN A 3CHROEDINGERS BEAN STATE 9OU MIGHT HAVE BEAN INITIALIZATION CODE LIKE GETTING A *$"# #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
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'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
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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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Q:
7HAT IF ) HAVE A NON 3ERIALIZABLE VALUE THAT ) REALLY NEED TO MAINTAIN DURING PASSIVATION )F ) CANT SAVE IT HOW WILL ) KNOW WHAT TO SET IT BACK TO IN EJB!CTIVATE
A:
4HIS IS A CLASSIC SERIALIZATION ISSUE NOT SPECIFIC TO PASSIVATION 4HE USUAL TRICK IS TO INTERROGATE THE NON 3ERIALIZABLE OBJECT TO GET ALL THE IMPORTANT STATE OUT OF IT AND STICK THAT STATE INTO INSTANCE VARIABLES THAT ARE 3ERIALIZABLE 4HEN DURING EJB!CTIVATE USE THE VALUES YOU WERE ABLE TO SAVE TO RECONSTRUCT THE NON 3ERIALIZABLE OBJECT SO THAT ITS IDENTICAL TO THE ONE YOU HAD BEFORE PASSIVATION &OR EXAMPLE IMAGINE YOU HAVE A $OG BEAN WITH A #OLLAR VARIABLE AND THE #OLLAR ISNT 3ERIALIZABLE )N EJB0ASSIVATE CALL GETTERS ON THE #OLLAR TO RETRIEVE THE VALUES THAT MATTER LIKE GET#OLOR GET3IZE ETC 3AVE THOSE VALUES IN INSTANCE VARIABLES IN THE BEAN THEN IN EJB!CTIVATE INSTANTIATE A NEW #OLLAR AND USE THE #OLLAR ATTRIBUTES YOU SAVED AS ARGUMENTS TO SETTERS ON THE NEW #OLLAR OBJECT
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'IVEN 0\%HDQFUHDWH 6WULQJQDPH WKURZV&UHDWH([FHSWLRQ 5HPRWH([FHSWLRQ 7HICH SESSION BEAN INTERFACE CAN CONTAIN THIS METHOD
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7HAT IS TRUE ABOUT A SESSION BEANS LIFECYCLE #HOOSE ALL THAT APPLY
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R" ! PASSIVATED BEAN MUST BE ACTIVATED BEFORE IT CAN BE REMOVED R# ! STATELESS SESSION BEANS REMOVAL MUST BE INITIATED BY THE CLIENT NOT THE CONTAINER
R$ 3TATELESS SESSION BEANS CANNOT IMPLEMENT THE 3ESSION3YNCHRONIZATION INTERFACE
8
7HICH ARE REQUIRED OF THE BEAN PROVIDER TO ENSURE THAT A SESSION BEAN IS SUCCESSFULLY PASSIVATED #HOOSE ALL THAT APPLY
R! 4HE PROVIDER MUST CALLHME3DVVLYDWH R" 4HE PROVIDER MUST ALWAYS ADD BUSINESS LOGIC TO THEHME3DVVLYDWH METHOD IF THE BEAN IS STATEFUL
R# 4HE PROVIDER MUST CLOSE ANY DATABASE CONNECTIONS BEFORE HME3DVVLYDWH COMPLETES
R$ 4HE PROVIDER MUST ASSUME THAT ANY STATE STORED IN INSTANCE lELDS MARKED TRANSIENT WILL BE LOST
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
9
'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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10
.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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7HAT IS TRUE ABOUT A SESSION BEANS LIFECYCLE #HOOSE ALL THAT APPLY
R! 4HE CONTAINER WILL ALWAYS CREATE A NEW SESSION BEAN INSTANCE WHEN THE CLIENT INVOKES THE FUHDWH METHOD ON THE HOME INTERFACE OF A STATELESS BEAN
R" 4HE CONTAINER WILL ALWAYS CALL HME5HPRYH WHEN THE CLIENT INVOKES THE UHPRYH METHOD ON A STATELESS BEANS HOME INTERFACE
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12
7HICH OF THE FOLLOWING METHODS ARE CONTAINER CALLBACK METHODS #HOOSE ALL THAT APPLY
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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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14
7HICH METHODS ALLOW BOTH STATEFUL AND STATELESS SESSION BEANS WITH BEAN MANAGED TRANSACTION DEMARCATION TO ACCESS 5SER4RANSACTION METHODS #HOOSE ALL THAT APPLY
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15
&OR WHICH TYPE OF BEAN CAN THE CONTAINER PASSIVATE AN INSTANCE THAT IS IN A TRANSACTION
R! ONLY STATEFUL SESSION BEANS R" ONLY STATELESS SESSION BEANS R# BOTH STATEFUL AND STATELESS SESSION BEANS R$ NEITHER STATEFUL NOR STATELESS SESSION BEANS
16
&OR SESSION BEANS WHICH ARE THE RESPONSIBILITY OF THE #ONTAINER #HOOSE ALL THAT APPLY
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17
&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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18
7HICH CAN BE CALLED BY THE CONTAINER DURING THE LIFECYCLE OF A SESSION BEAN #HOOSE ALL THAT APPLY
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19
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7HICH STATEMENTS ABOUT A SESSION BEAN CLASS ARE TRUE #HOOSE ALL THAT APPLY
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7HICH STATEMENTS ARE TRUE FOR STATELESS SESSION BEAN INSTANCES #HOOSE ALL THAT APPLY
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2
(spec: 77)
7HICH LISTS CORRECTLY SEQUENCE SOME OF THE STEPS IN A SESSION BEANS LIFECYCLE #HOOSE ALL THAT APPLY
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(spec: 71)
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7HICH ARE VALID REMOTE COMPONENT INTERFACES FOR A SESSION BEAN #HOOSE ALL THAT APPLY
(spec: 97)
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(spec: 79)
)F A CLIENT MAKES A CALL TO A SESSION OBJECT THAT HAS BEEN REMOVED BY THE CONTAINER WHICH EXCEPTIONS CAN BE THROWN #HOOSE ALL THAT APPLY
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(spec: 98)
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7HAT IS TRUE ABOUT A SESSION BEANS LIFECYCLE #HOOSE ALL THAT APPLY
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(spec: 79, 88) killed - no, the bean is
PASSIVATED
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8
7HICH ARE REQUIRED OF THE BEAN PROVIDER TO ENSURE THAT A SESSION BEAN IS SUCCESSFULLY PASSIVATED #HOOSE ALL THAT APPLY
(spec: 71-72)
R! 4HE PROVIDER MUST CALLHME3DVVLYDWH R" 4HE PROVIDER MUST ALWAYS ADD BUSINESS LOGIC TO THEHME3DVVLYDWH METHOD IF THE BEAN IS STATEFUL
R# 4HE PROVIDER MUST NOT CLOSE ANY DATABASE CONNECTIONS BEFORE HME3DVVLYDWH COMPLETES
R$ 4HE PROVIDER MUST ASSUME THAT ANY STATE STORED IN INSTANCE lELDS MARKED TRANSIENT WILL BE LOST
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Container MUST passivate your context
9
'IVEN A STATELESS SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCATION FROM WHICH METHODS CAN YOU ACCESS ANOTHER BEAN #HOOSE ALL THAT APPLY
(spec: 90)
R! HME&UHDWH R" HME5HPRYH R# A BUSINESS METHOD - also true for stateless BMT beans R$ VHW6HVVLRQ&RQWH[W
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(API docs)
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3ESSION3YNCHRONIZATION
(spec: 70)
7HAT IS TRUE ABOUT A SESSION BEANS LIFECYCLE #HOOSE ALL THAT APPLY
R! 4HE CONTAINER WILL ALWAYS CREATE A NEW SESSION BEAN INSTANCE WHEN THE CLIENT INVOKES THE FUHDWH METHOD ON THE HOME INTERFACE OF A STATELESS BEAN - Container makes stateless beans whenever it wants
R" 4HE CONTAINER WILL ALWAYS CALL HME5HPRYH WHEN THE CLIENT INVOKES - Container remove THE UHPRYH METHOD ON A STATELESS BEANS HOME INTERFACE
s stateless bean ONLYa when it wants to shrink the pool
R# ! SESSION BEAN CANNOT BE PASSIVATED WHILE IT IS IN A TRANSACTION R$ 4HE VHW6HVVLRQ&RQWH[W METHOD IS NOT INVOKED DURING A STATELESS BEANS LIFECYCLE
12
7HICH OF THE FOLLOWING METHODS ARE CONTAINER CALLBACK METHODS #HOOSE ALL THAT APPLY
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)N WHAT CASES WILL THE CONTAINER FAIL TO CALL EJB2EMOVE ON A SESSION BEAN #HOOSE ALL THAT APPLY
(spec: 82)
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14
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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15
&OR WHICH TYPE OF BEAN CAN THE CONTAINER PASSIVATE AN INSTANCE THAT IS IN A TRANSACTION
(spec: 70)
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16
&OR SESSION BEANS WHICH ARE THE RESPONSIBILITY OF THE #ONTAINER #HOOSE ALL THAT APPLY
it
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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
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18
7HICH CAN BE CALLED BY THE CONTAINER DURING THE LIFECYCLE OF A SESSION BEAN #HOOSE ALL THAT APPLY
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19
20
7HICH STATEMENTS ABOUT A SESSION BEAN CLASS ARE TRUE #HOOSE ALL THAT APPLY
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(spec: 95)
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7HICH STATEMENTS ARE TRUE FOR STATELESS SESSION BEAN INSTANCES #HOOSE ALL THAT APPLY
(spec: 88)
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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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7ITH SESSION BEANS THAT WAS EASYA REFERENCE TO THE COMPONENT INTERFACE !ND THATS EXACTLY WHAT THE CREATE METHODS HAVE TO GIVE BACK 7ITH ENTITY BEANS ITS THE SAME FOR CREATE METHODSTHEY MUST GIVE BACK A REFERENCE TO THE COMPONENT INTERFACE IN THIS CASE THE COMPONENT INTERFACE FOR THE ENTITY JUST CREATED "UT WHAT IF YOU WANT TO l ND AN EXISTING ENTITY BEAN INSTEAD OF MAKING A NEW ONE 4HATS WHAT THE MANDATORY l ND"Y0RIMARY+EY METHOD IS FOR AND IT TOO MUST GIVE BACK A REFERENCE TO THE COMPONENT INTERFACE FOR THE BEAN MATCHING THAT KEY "UT WHAT IF THERE ISNT A MATCHING ENTITY )F THERES NO ENTITY WITH THAT KEY IN THE DATABASE THE CLIENT GETS A JAVAXEJB/BJECT .OT&OUND%XCEPTION 3O THE RETURN TYPE OF l ND"Y0RIMARY+EY IS ALWAYS THE SAME AS IT IS FOR CREATE THE COMPONENT INTERFACE FOR THAT BEAN TYPE !ND OF COURSE THE RULES FOR SESSION BEAN CLIENT INTERFACES APPLIES HERE AS WELLA 2EMOTE HOME INTERFACE MUST GIVE BACK THE 2EMOTE COMPONENT INTERFACE AND THE LOCAL HOME INTERFACE MUST GIVE BACK THE LOCAL COMPONENT INTERFACE 4HIS STILL LEAVES US WITH A METHOD THAT CANNOT RETURN THE COMPONENT INTERFACE A MULTIPLE ENTITY l NDER LIKE OUR l ND"Y#ITY METHOD 7ELL THE CLIENTS GOAL DOESNT CHANGE WITH MULTIPLE ENTITY l NDERS THE CLIENT STILL WANTS A REFERENCE TO THE COMPONENT INTERFACE ONLY THIS TIME IT MIGHT BE A WHOLE COLLECTION OF THEM /NE FOR EVERY CUSTOMER ENTITY IN THE CITY NAMED IN THE METHODS ARGUMENT .OTE A CLIENT WILL NOT GET AN EXCEPTION IF A MULTI ENTITY l NDER CANT l ND ANY MATCHES )NSTEAD THE CLIENT WILL STILL GET A #OLLECTION BUT IT WILL SIMPLY BE EMPTY ! #OLLECTION WITH NO ELEMENTS /NLY SINGLE ENTITY l NDERS THROW EXCEPTIONS WHEN NOTHING MATCHES THE l ND CRITERIA
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7AIT ) THOUGHT IT WAS BAD DESIGN TO MAKE ALL THOSE METHOD CALLS FROM THE CLIENT !.97!9 7OULDNT THE CLIENT USUALLY GO THROUGH A SESSION BEAN !ND THE SESSION BEAN WOULD THEN TALK TO THE ENTITY BEAN
A:
+IND OF 9OURE THINKING OF THE 3ES SION &ACADE *%% DESIGN PATTERN "UT EVEN IF YOU DO PUT A SESSION BEAN IN FRONT OF AN ENTITY BEAN THE SESSION BEAN IS STILL A CLIENT )T MIGHT BE A LOT MORE EFFICIENT BECAUSE THE SESSION BEAN MIGHT NOT HAVE AS FAR TO GO ON THE NETWORK AND MIGHT EVEN BE ON THE SAME SERVER AS THE ENTITY "UT IF YOURE KEEPING LOCATION INDEPENDENCE THEN YOUR SESSION BEAN IS STILL USING THE ENTITY BEANS 2EMOTE INTERFACES SO THERES STILL A LOT OF OVERHEAD
Q:
#OULDNT YOU JUST HAVE A BUSINESS METHOD IN THE COMPONENT INTERFACE THAT RETURNS DATA ,IKE RETURN A COLLECTION OF 3TRINGS
A:
9OURE GETTING WARMER 9ES THATS THE WAY YOU MIGHT HAVE DONE IT IN %*" "UT THATS KLUDGEY BECAUSE YOU HAVE TO FIRST GET A REFERENCE TO SOME CUSTOMER JUST SO YOU CAN ASK THAT CUSTOMER TO GIVE YOU BACK THE DATA FOR ALL CUSTOMERS \RXDUHKHUH
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0WUMJ][QVM[[UM\PWL[\W\PMZM[K]M 4HATS RIGHT BUSINESS METHODS ARENT JUST FOR THE COMPONENT INTERFACE WHEN YOURE TALKING ABOUT ENTITY BEANS !S OF %*" AN ENTITY BEAN HOME CAN HAVE METHODS THATDRUM ROLLDONT HAVE TO RETURN COMPONENT INTERFACES (OME BUSINESS METHODS CAN RETURN ANYTHING WITH THE ONE RESTRICTION OF COURSE THAT 2EMOTE HOME METHODS RETURN VALUES THAT ARE 2-) ))/0 COMPLIANT (OME BUSINESS METHODS ARE GREAT FOR BATCH OPERATIONS OR FOR QUERY METHODS WHERE THE CLIENT DOESNT NEEDOR WANT%*" OBJECT REFERENCES BUT SIMPLY WANTS THE ENTITYS DATA IN OTHER WORDS THE DATA FOR ONE OR MORE OF THE ENTITYS PERSISTENT lELDS &OR EXAMPLE WE MIGHT PUT A HOME BUSINESS METHOD IN THE #USTOMER BEAN LIKE GET!LL#USTOMER)NFO THAT RETURNS A COLLECTION OF 3TRINGS WITH WHATEVER PIECES OF DATA YOUVE DECIDED MAKE UP THE CUSTOMERS INFO "ETTER YET YOU CAN SEND BACK A COLLECTION OF #USTOMER)NFO OBJECTS WHERE #USTOMER)NFO IS A CLASS THAT SIMPLY HOLDS THE DATA AND GETTERS FOR THE #USTOMERS PERSISTENT STATE 4HAT WAY THE CLIENT CAN MAKE LOCAL CALLS TO GET THE DATA IT NEEDS OUT OF THE #USTOMER)NFO OBJECTS WITHOUT HAVING THOSE CALLS BE REMOTE CALLS ON THE COMPONENT INTERFACE ! #USTOMER)NFO CLASS IS AN EXAMPLE OF A 6ALUE /BJECT CLASS WHICH IS IN A NUTSHELL JUST A CLASS WITH GETTERS AND POSSIBLY SETTERS DEPENDING ON THE DESIGN REPRESENTING THE ENTITYS PERSISTENT lELDS !ND IT TOO HAS A DARK SIDETHE DATA STARTS TO BECOME STALE THE MOMENT AFTER THE 6ALUE /BJECT IS CREATED 7E COULD TELL YOU NOW BUT THEN WED BE ROBBING YOU OF SUCH A VALUABLE OPPORTUNITY TO APPLY A LITTLE NEURAL EFFORT 3O FOR NOW WHY DONT YOU THINK OF WHY SENDING BACK #USTOMER)NFO OBJECTS THAT THE CLIENT COULD THEN INTERROGATE IE CALL METHODS ON AT ITS LEISURE COULD HAVE A DOWNSIDE 7ELL USE 6ALUE /BJECTS A LOT BUT YOU HAVE TO BE AWARE OF THE TRADEOFFS WHEN CHOOSING BETWEEN USING A HOME lNDER METHOD THAT RETURNS %*" OBJECT REFERENCES ESPECIALLY WHEN THE REFERENCES ARE 2EMOTE VS A HOME BUSINESS METHOD THAT RETURNS 6ALUE /BJECTS
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%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
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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
Q:
"UT COULDNT OPTION ! REALLY KILL ME IF ) WANT TO KEEP THE ENTITIES UNLOCKED IN THE DATABASE WHEN THEYRE NOT BEING USED BY THE BEAN
A:
&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
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!H NOW WE COME TO THE DIFFERENCE BETWEEN THE hCONCEPTUALv VIEW OF THE ARCHITECTURE AND THE hACTUALv IMPLEMENTATION !CCORDING TO THE SPEC YOURE
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7HICH OF THE THREE COMMIT OPTIONS DO YOU THINK IS MOST USED
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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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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
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4HEN SHOULDNT YOUR GOAL BE TO HAVE THE LONGEST TRANSACTIONS
A:
9OU ARENT BEING SERIOUS RIGHT *UST FOR FUN WELL PRETEND YOU ARE AND SAY ./ ./ ./ ./ 4HINK ABOUT YOUR CONCURRENCY ! GOOD RULE OF THUMB WITH A ZILLION EXCEPTIONS OF COURSE SO ALL RULE OF THUMB DISCLAIMERS APPLY IS THAT TRANSACTIONS SHOULD BE NO LONGER THAN ABSOLUTELY NECESSARY 4HE LONGER YOUR BEAN IS IN A TRANSACTION THE MORE LIKELY IT IS THAT OTHERS ARE WAITING IN LINE TO GET TO THAT ENTITY /F COURSE ITS ALSO POSSIBLE TO HAVE TRANSACTIONS WHICH ARE TOO SHORT WHICH MEANS
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/NE MORE THING DOESNT THIS MEAN THAT EJB0ASSIVATE AND EJB!CTIVATE MIGHT NOT EVER BE CALLED ON A BEAN IF THE CONTAINER USES OPTION ! OR " !ND DOESNT THIS MEAN THAT ) SHOULDNT RELY ON EJB!CTIVATE OR EJB0ASSIVATE IN MY DESIGN
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r t Þelds, by calling ourence en ist rs pe r ou t se we refe Here e must NOT try toTha t has to abstract setters. WRE . PS HI ATIONS L t en ist rs pe n happens ow at our en inserted, and th be ve ha E W l ti un it wa e() completes. only AFTER ejbCreat
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 `
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We have FIVE virtual Þelds: four CMP Þelds and one CMR Þeld for Director.
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there are no
Dumb Questions
Q:
(OW DOES *-3 lT INTO ALL THIS !ND IF ) HAVE A MESSAGE DRIVEN BEAN WHERE DO ) GET THE MESSAGING SERVICE
A:
*-3 IS THE *AVA -ESSAGING 3ERVICE !0) THATS REQUIRED BY %*" 4HAT MEANS YOUR %*" CONTAINER MUST HAVE SOME KIND OF MESSAGING SERVICE INCLUDED ALTHOUGH MANY VENDORS CAN WORK WITH MULTIPLE MESSAGING SERVICES AS LONG AS THOSE SERVICES SUPPORT THE *-3 !0) 4HE *-3 !0) WORKS MUCH LIKE *$"# YOU HAVE A DRIVER THAT KNOWS HOW TO TAKE YOUR STANDARD *-3 !0) CALLS AND TRANSLATE THEM INTO SOMETHING THE UNDERLYING MESSAGING SYSTEM UNDERSTANDS
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
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Q:
7HY DOESNT THE -ESSAGE$RIVEN"EAN JUST EXTEND THE -ESSAGE,ISTENER INTERFACE 4HAT WAY YOU WOULDNT HAVE TO IMPLEMENT BOTH INTERFACES
A:
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
A:
.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:
)F ITS A TOPIC DOES THAT MEAN ALL BEANS IN A PARTICULAR SUBSCRIBER POOL WILL GET THE MESSAGE
A:
.O 2EMEMBER ONE BEAN CAN STAND IN FOR ALL THE OTHER BEANS 4HE #ONTAINER WILL DELIVER THE MESSAGE TO JUST /.% BEAN IN THE POOL 5NLESS NO NEVER MIND
Q: A:
5NLESS WHAT 4ELL ME
/+ /+ "UT THIS ISNT ON THE EXAM SO RELAX ,ETS SAY YOUR SERVER IS RUNNING AS A CLUSTERED CONFIGURATION WHERE YOU COULD HAVE MULTIPLE INSTANCES OF YOUR SERVER RUNNING )N THAT CASE THERE IS NO GUARANTEE ABOUT HOW THE #ONTAINER WILL REPRESENT ITSELF TO THE MESSAGING SERVICE 4HE QUESTION BECOMES DOES THE MESSAGING SERVICE SEE THE WHOLE CLUSTER AS /.% VERSION OF YOUR APPLICATION NO MATTER HOW MANY *6-S ITS RUNNING ON OR DOES THE MESSAGING SERVICE SEE EACH CLUSTER WITH ITS OWN DUPLICATED POOL FOR EACH BEAN TYPE AS A SEPARATE LISTENER
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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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?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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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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9OU KEEP SAYING THAT MESSAGE DRIVEN BEANS DONT HAVE CLIENTS "UT 3/-%"/$9 HAS TO CALL THE BEANS METHODS RIGHT 4HEY DONT CALL THEMSELVES
A:
4ECHNICALLY YES THE BEANS METHODS ARE CALLED "UT WE DONT CONSIDER THE #ONTAINER TO BE A CLIENT )TS THE BOSS NOT THE CUSTOMER 3O IN THE *AVA SENSE THE #ONTAINER IS THE BEANS CALLER BUT NOT A CLIENT !ND AS FOR GETTING SECURITY INFO IF THE BEAN DOESNT TRUST ITS OWN #ONTAINER YOU HAVE WAAAAY BIGGER PROBLEMS 7ERE TALKING ONE SERIOUSLY PARANOID BEAN
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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
7KHPHWKRGFRPSOHWLRQ -ESSAGE ACKNOWLEDGEMENT IS TIED TO WHETHER THE METHOD COMPLETES SUCCESSFULLY )F THE METHOD THROWS A RUNTIME EXCEPTION THE MESSAGE GOES BACK ON THE QUEUE 9OU GET THIS BEHAVIOR FOR BEANS THAT USE BEAN MANAGED TRANSACTION DEMARCATION
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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 $UPS OK ACKNOWLEDGE YOURE TELLING THE #ONTAINER THAT YOU DONT MIND IF ITS KIND OF SLOW WITH THE ACKNOWLEDGEMENT TO THE MESSAGE SERVICE THAT YOU DONT MIND IF YOU GET DUPLICATE MESSAGES hDUPS OKv 4HIS LETS THE #ONTAINER TAKE WHATEVER TIME IT WANTS TO DO THE ACKNOWLEDGEMENT AND IT MIGHT MAKE THE SERVER MORE EFlCIENT BUT AT THE RISK OF DUPLICATE MESSAGES BECAUSE THE POOR MESSAGING SERVICE DIDNT GET AN ACKNOWLEDGEMENT QUICKLY ENOUGH
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7HATS TRUE ABOUT MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
R! ! MESSAGE DRIVEN BEAN HAS A HOME INTERFACE BUT NO COMPONENT INTERFACE
R" ! CLIENT NEVER KNOWS A MESSAGE DRIVEN BEANS IDENTITY R# ! CLIENT SEES A MESSAGE DRIVEN BEAN AS A *AVA-AIL MESSAGE CONSUMER R$ 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
R! MDYD[MPV0HVVDJH R" MDYD[MPV0HVVDJH/LVWHQHU R# MDYD[MPV0HVVDJH&RQVXPHU R$ MDYD[HME0HVVDJH'ULYHQ%HDQ R% MDYD[HME0HVVDJH'ULYHQ&RQWH[W
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7HICH LIST PROPERLY SEQUENCES THE METHODS CALLED IN THE LIFECYCLE OF A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
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7HICH ARE VALID SIGNATURES FOR METHODS IN A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
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7HEN IS A MESSAGE DRIVEN BEAN ABLE TO ACCESS JAVACOMPENV VIA *.$)
6
7HICH MESSAGE DRIVEN BEAN METHODS TAKE AN ARGUMENT #HOOSE ALL THAT APPLY
R! HME&UHDWH R" HME5HPRYH R# VHW0HVVDJH'ULYHQ&RQWH[W R$ .ONE OF THE ABOVE
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7
7HEN IS A MESSAGE DRIVEN BEAN ABLE TO ACCESS OTHER ENTERPRISE BEANS
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8
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
7HEN IS A MESSAGE DRIVEN BEAN WITH "-4 DEMARCATION ABLE TO ACCESS RESOURCE MANAGERS
R! HME&UHDWH R" HME5HPRYH R# RQ0HVVDJH R$ VHW0HVVDJH'ULYHQ&RQWH[W R% .ONE OF THE ABOVE
10
7HATS TRUE ABOUT MESSAGE ACKNOWLEDGMENT FOR MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
R! -ESSAGE ACKNOWLEDGEMENT MODES CANNOT BE DElNED DECLARATIVELY R" 4HE *-3 !0) SHOULD BE USED FOR MESSAGE ACKNOWLEDGMENT R# &OR "-4 BEANS THE #ONTAINER USES THE ACKNOWLEDGE MODE DEPLOYMENT DESCRIPTOR ELEMENT
R$ &OR #-4 BEANS THE #ONTAINER USES THE ACKNOWLEDGE MODE DEPLOYMENT DESCRIPTOR ELEMENT
11
7HATS TRUE ABOUT THE DEPLOYMENT DESCRIPTOR FOR MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
R! 4HE BEAN PROVIDER MUST GUARANTEE THAT THE BEAN IS ASSOCIATED WITH A SPECIlC QUEUE OR TOPIC
R" 4HE DEPLOYMENT DESCRIPTOR CAN INDICATE WHETHER A BEAN IS INTENDED FOR A TOPIC OR A QUEUE
R# )T CAN INDICATE WHETHER A 1UEUE TYPE BEAN SHOULD SUPPORT DURABLE SUBSCRIPTION OR NOT
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7HATS TRUE ABOUT MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
R! ! MESSAGE DRIVEN BEAN HAS A HOME INTERFACE BUT NO COMPONENT INTERFACE
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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)
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7HICH LIST PROPERLY SEQUENCES THE METHODS CALLED IN THE LIFECYCLE OF A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
(spec: 319)
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7HICH ARE VALID SIGNATURES FOR METHODS IN A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
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7HEN IS A MESSAGE DRIVEN BEAN ABLE TO ACCESS OTHER ENTERPRISE BEANS
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R! HME&UHDWH ful R" HME5HPRYH d with a Ômeaning ho et m a in ly on R# RQ0HVVDJH -transaction contextÕ R$ VHW0HVVDJH'ULYHQ&RQWH[W R% .ONE OF THE ABOVE
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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
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7HEN IS A MESSAGE DRIVEN BEAN WITH "-4 DEMARCATION ABLE TO ACCESS RESOURCE MANAGERS
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R! HME&UHDWH R" HME5HPRYH R# RQ0HVVDJH - when there is a Ômeaningful transaction contextÕ R$ VHW0HVVDJH'ULYHQ&RQWH[W R% .ONE OF THE ABOVE
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(spec: 317)
7HATS TRUE ABOUT MESSAGE ACKNOWLEDGMENT FOR MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
R! -ESSAGE ACKNOWLEDGEMENT MODES CANNOT BE DElNED DECLARATIVELY R" 4HE *-3 !0) SHOULD BE USED FOR MESSAGE ACKNOWLEDGMENT R# &OR "-4 BEANS THE #ONTAINER USES THE ACKNOWLEDGE MODE DEPLOYMENT DESCRIPTOR ELEMENT
R$ &OR #-4 BEANS THE #ONTAINER USES THE ACKNOWLEDGE MODE
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DEPLOYMENT DESCRIPTOR ELEMENT
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(spec: 317)
7HATS TRUE ABOUT THE DEPLOYMENT DESCRIPTOR FOR MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
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) JUST REALIZED SOMETHING THE CONTAINER CALLBACKS DECLARED IN THE 3ESSION"EAN AND %NTITY"EAN INTERFACES DONT DECLARE CHECKED EXCEPTIONS RIGHT 3O DOESNT THIS MEAN THAT YOU CANT THROW AN APPLICATION EXCEPTION FROM SAY EJB!CTIVATE
9OU SAID THE INTERFACES DONT DECLARE ANY CHECKED EXCEPTIONS 4(!4 9/5 #!. 53% 7HAT DOES THAT MEAN 7HATS AN EXAMPLE OF A DECLARED CHECKED EXCEPTION THAT YOU CANT USE
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)F YOU GO TO THE *%% !0) WELL WAIT WHILE YOU DO THAT STILL WAITING WAITING WAITING YOU CAN SEE THAT ALL OF THE METHODS DECLARE A 2EMOTE%XCEPTION 9ES A "IG &AT #HECKED EXCEPTION 4HEY ALSO DECLARE %*"%XCEPTION AS A NICE GESTURE BUT NOT A REQUIREMENT SINCE %*"%XCEPTION IS A SUBCLASS OF 2UNTIME%XCEPTION $OES THIS MEAN YOU CAN THROW A 2EMOTE%XCEPTION YOURSELF ,IKE IF YOU CAUGHT ONE WHILE YOUR BEAN IS BEING A CLIENT TO ANOTHER BEAN FOR EXAMPLE ./ ./ ! TIMES ./
4HATS RIGHT 9OU CAN THROW ONLY UNCHECKED EXCEPTIONS FROM A CONTAINER CALLBACK THAT IS NOT PART OF YOUR CLIENT VIEW 4HIS IS JUST PLAIN OLD *AVA YOU CANT THROW A CHECKED EXCEPTION FROM A METHOD THAT DOESNT DECLARE THE EXCEPTION AND SINCE THOSE INTERFACES DONT DECLARE ANY CHECKED EXCEPTIONS THAT YOU CAN USE YOURE STUCK WITH RUNTIME EXCEPTIONS 4HE ONLY THING YOU SHOULD THROW FROM ONE OF THE CONTAINER CALLBACKS OF 3ESSION"EAN %NTITY"EAN OR -ESSAGE$RIVEN"EAN IS AN %*"%XCEPTION
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5HPRYH([FHSWLRQ 4HE CLIENT DOES NOT KNOW FOR CERTAIN WHETHER THE BEAN WAS ACTUALLY REMOVED 4HE BEAN PROVIDER MIGHT SIMPLY HAVE REJECTED THE CLIENTS REQUEST AS IN h9OU CAN ASK ALL DAY LONG BUT THERE IS NO 7!9 THAT )M GOING TO REMOVE THAT ENTITY FROM THE DATABASEv /R THE ENTITY MIGHT HAVE BEEN REMOVED FROM THE DATABASE BUT THEN SOMETHING ELSE WENT WRONG THAT TRIGGERED THE 2EMOVE%XCEPTION \RXDUHKHUH
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A:
2EMEMBER THERES NOTHING IN THE BEAN CLASS THAT CAN TELL YOU WHETHER THE BEAN IS DEFINITELY STATELESS 9OU CAN TELL IF A BEAN IS STATEFUL OF COURSE BECAUSE ANY BEAN WITH OVERLOADED CREATES OR ITS ONLY CREATE HAS ARGS MUST BE STATEFUL "UT EVEN IF A SESSION BEAN HAS ONLY A SINGLE NO ARG CREATE METHOD YOU STILL DONT KNOW WHETHER THAT BEAN IS GOING TO BE MARKED STATELESS OR STATEFUL AT DEPLOYTIME 4HIS WOULD ALL BE DIFFERENT IF THERE WERE A SEPARATE INTERFACE FOR 3TATELESS3ESSION"EAN AND 3TATEFUL3ESSION"EAN THAT YOUR BEAN HAD TO IMPLEMENT INSTEAD OF JUST 3ESSION"EAN BUT THATS NOT HOW IT WORKS
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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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+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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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
4HE #ONTAINER THROWS THIS TO THE CALLER WHEN THE #ONTAINER CANT COMMIT THE TRANSACTION AND THE CALLER INVOKED THE METHOD WITHIN AN EXISTING TRANSACTION CONTEXT "UT THE #ONTAINER WILL NOT THROW THIS EXCEPTION IF THE FAILURE TO COMMIT IS BECAUSE THE BEAN EXPLICITLY CALLED THE SET2OLLBACK/NLY METHOD )N THAT CASE THE #ONTAINER WILL ROLLBACK THE TRANSACTION AND PASS THE BUSINESS METHOD RESULT BACK TO THE CLIENT UNLESS THE BEAN ALSO THROWS AN APPLICATION EXCEPTION
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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 $OESNT MATTER !S FAR AS THE CLIENTS CONCERNED THE PHONE HAS BEEN DISCONNECTED OVER AT THE SERVER SIDE .O3UCH/BJECT,OCAL%XCEPTION WAS ADDED WHEN LOCAL CLIENT VIEWS WERE ADDED IN %*" 4HE CONCEPT IS SLIGHTLY DIFFERENT BECAUSE THE LOCAL CLIENT IS USING NOT A STUB BUT A REAL *AVA OBJECT REFERENCE "UT FROM THE CLIENTS PERSPECTIVE IT REALLY DOESNT MATTER WHETHER ITS LOCAL OR 2EMOTEA .O3UCH/BJECT WHATEVER EXCEPTION MEANS YOU CANT USE YOUR %*" OBJECT REFERENCE TO GET TO A BEAN 9OU HAVE TO GO BACK THROUGH THE HOME AND START OVER \RXDUHKHUH
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7HICH SCENARIO WILL CAUSE A JAVARMI.O3UCH/BJECT%XCEPTION TO BE THROWN #HOOSE ALL THAT APPLY
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R" ! REMOTE CLIENT INVOKES A METHOD ON AN ENTITY BEAN WHICH HAS BEEN REMOVED
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7HICH OF THE FOLLOWING ARE %*" SPECIlCATION GUIDELINES REGARDING SYSTEM EXCEPTIONS #HOOSE ALL THAT APPLY
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7HICH IS A SUBCLASS OF JAVAXEJB&INDER%XCEPTION #HOOSE ALL THAT APPLY
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&ROM WHICH METHODS CAN -$"S WITH #-4 DEMARCATION THROW APPLICATION EXCEPTIONS #HOOSE ALL THAT APPLY
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7HATS TRUE FOR A LOCAL CLIENT THAT RECEIVES AN EXCEPTION FROM AN %*" INVOCATION #HOOSE ALL THAT APPLY
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7HICH ACTIONS WILL THE CONTAINER TAKE IF A MESSAGE DRIVEN BEAN WITH "-4 DEMARCATION THROWS A SYSTEM EXCEPTION #HOOSE ALL THAT APPLY
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&ROM WHICH TYPES OF BEANS CAN CLIENTS RECEIVE SYSTEM EXCEPTIONS #HOOSE ALL THAT APPLY
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2
(spec: 374)
(spec: 374)
7HICH SCENARIO WILL CAUSE A JAVARMI.O3UCH/BJECT%XCEPTION TO BE THROWN #HOOSE ALL THAT APPLY
R! ! REMOTE CLIENT INVOKES A METHOD ON A STATEFUL SESSION BEAN WHICH HAS BEEN REMOVED
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7HICH IS A SUBCLASS OF JAVALANG2UNTIME%XCEPTION #HOOSE ALL THAT APPLY
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7HICH OF THE FOLLOWING ARE %*" SPECIlCATION GUIDELINES REGARDING SYSTEM EXCEPTIONS #HOOSE ALL THAT APPLY
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(spec: 373-374
R! "EAN METHODS SHOULD CATCH 2UNTIME%XCEPTION EXCEPTIONS R" "EAN METHODS SHOULD WRAP UNRECOVERABLE CHECKED EXCEPTIONS IN A MDYD[HME(-%([FHSWLRQ EXCEPTION
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)F A BUSINESS METHOD OF A #-4 DEMARCATED BEAN THROWS A SYSTEM EXCEPTION IN WHICH CASE WILL THE CONTAINER ALWAYS THROW A MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5ROOHGEDFN([FHSWLRQ #HOOSE ALL THAT APPLY
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(spec: 375-376)
The others are wrong because they indicate that the callerÕs tx was not the active tx when the exception occurred. ThereÕs no need to tell a caller (through an exception) unless itÕs the callerÕs transaction that is rolled back!
6
7HICH IS A SUBCLASS OF JAVAXEJB&INDER%XCEPTION #HOOSE ALL THAT APPLY
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&ROM WHICH METHODS CAN -$"S WITH #-4 DEMARCATION THROW APPLICATION EXCEPTIONS #HOOSE ALL THAT APPLY
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(spec: 263-264
R! #REATE%XCEPTION R" .O3UCH%NTITY%XCEPTION R# 2EMOVE%XCEPTION R$ $UPLICATE+EY%XCEPTION - subclass of CreateException R% /BJECT.OT&OUND%XCEPTION
(spec: 377)
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7HATS TRUE FOR A LOCAL CLIENT THAT RECEIVES AN EXCEPTION FROM AN %*" INVOCATION #HOOSE ALL THAT APPLY
(spec: 381-382)
R! 4HE EXCEPTION MIGHT BE FROM THE JAVARMI PACKAGE R" 4HE EXCEPTION MIGHT BE AN APPLICATION EXCEPTION R# 4HE EXCEPTION MIGHT BE A SYSTEM EXCEPTION R$ .ONE OF THE ABOVE
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7HICH ACTIONS WILL THE CONTAINER TAKE IF A MESSAGE DRIVEN BEAN WITH "-4 DEMARCATION THROWS A SYSTEM EXCEPTION #HOOSE ALL THAT APPLY
(spec: 378)
R! ,OG THE EXCEPTION R" $ISCARD THE INSTANCE R# -ARK THE TRANSACTION FOR ROLLBACK R$ #OMMIT THE TRANSACTION UNLESS THE BEAN HAS INVOKED VHW5ROOEDFN2QO\
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&ROM WHICH TYPES OF BEANS CAN CLIENTS RECEIVE SYSTEM EXCEPTIONS #HOOSE ALL THAT APPLY
R! 3ESSION BEANS WITH #-4 DEMARCATION R" 3ESSION BEANS WITH "-4 DEMARCATION R# -ESSAGE DRIVEN BEANS WITH #-4 DEMARCATION - MDBs have no clients! R$ -ESSAGE DRIVEN BEANS WITH "-4 DEMARCATION R% %NTITY BEANS WITH #-4 DEMARCATION
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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
R! BEAN PROVIDER R" APPLICATION ASSEMBLER R# DEPLOYER R$ CONTAINER PROVIDER R% SYSTEM ADMINISTRATOR
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(spec: 422)
Appendix A:
Final Mock Exam
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7HICH ARE BENElTS OF %*" #HOOSE ALL THAT APPLY
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 R% $ECLARATIVE ISOLATION LEVEL SETTINGS
2
7HICH METHODS ARE DIRECTLY INVOKED BY THE CLIENT #HOOSE ALL THAT APPLY
3
7HICH METHODS CAN BE FOUND IN THE %*"(OME INTERFACE #HOOSE ALL THAT APPLY
R! HME3DVVLYDWH R" BUSINESS METHODS R# VHW6HVVLRQ&RQWH[W R$ QHZ,QVWDQFH R% FUHDWH
R! REMOVE(ANDLE HANDLE R" REMOVE/BJECT PRIMARY+EY R# GET(ANDLE R$ NONE OF THE ABOVE
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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
5
7HATS TRUE ABOUT MESSAGE DRIVEN BEANS #HOOSE ALL THAT APPLY
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
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
6
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
R" /NLY THE BEAN PROVIDER CAN SET AN ENVIRONMENT ENTRY VALUE R# ! BEANS ENVIRONMENT ENTRIES CAN BE STORED ONLY IN µMDYD FRPSHQY¶OR ONE OF ITS SUBCONTEXTS
R$ %VERY ENVIRONMENT ENTRY LOOKUP IN A BEANS CODE MUST HAVE A MATCHING HQYHQWU\! ELEMENT IN THE BEANS DEPLOYMENT DESCRIPTOR
7
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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!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
9
7HICH STATEMENTS CONCERNING STATELESS SESSION BEANS ARE TRUE #HOOSE ALL THAT APPLY
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
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
11
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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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
15
7ITHIN THE DEPLOYMENT DESCRIPTORS HMEORFDOUHI! ELEMENT WHICH ELE MENTS ARE OPTIONAL #HOOSE ALL THAT APPLY
R! ORFDO! R" HMEOLQN! R# ORFDOKRPH! R$ GHVFULSWLRQ! R% HMEUHIQDPH! R& HMEUHIW\SH! \RXDUHKHUH
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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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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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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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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
R! JHW(-%+RPH R" JHW(-%2EMHFW R# JHW(-%7UDQVDFWLRQ R$ LV&DOOHU,Q5ROH R% JHW8VHU7UDQVDFWLRQ
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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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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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7HICH ARE VALID LOCAL HOME INTERFACES FOR A STATEFUL SESSION BEAN #HOOSE ALL THAT APPLY
R! SXEOLFLQWHUIDFH7HVW%HDQLPSOHPHQWV MDYD[HME(-%/RFDO+RPH^ Y RLGFUHDWH WKURZV&UHDWH([FHSWLRQ `
R" SXEOLFLQWHUIDFH7HVW%HDQH[WHQGV 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
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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 `
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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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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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(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
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'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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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
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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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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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)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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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
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R! 3%,%#4 #USTOMER
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7(%2% CCUSTNUM OCUSTNUM
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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
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60
0 0DQGDWRU\
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R! SGLVFRXQW 25SGLVFRXQW! R" SGLVFRXQW 25SGLVFRXQW! R# SGLVFRXQW 25SGLVFRXQW! R$ SGLVFRXQW 25SGLVFRXQW!
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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
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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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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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7HICH ARE VALID DEPLOYMENT DESCRIPTOR SEGMENTS TO DElNE A CMR lELD #HOOSE ALL THAT APPLY
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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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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
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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(API docs)
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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
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 onMessa ge 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 by t se ly al ic yp t R" /NLY THE BEAN PROVIDER CAN SET AN ENVIRONMENT ENTRY VALUE Application Assembler 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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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
R! HME/RDG s ve to allow client ha Õt on d u yo R" HME&UHDWH tities to insert new en R# HME5HPRYH R$ HME6HOHFW R% HME3DVVLYDWH R& VHW(QWLW\&RQWH[W
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(spec: 171-174)
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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 arity to one ent
(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
- bean just goes back to the pool R" 4HE ON0HVVDJH METHOD CAN THROW APPLICATION EXCEPTIONS - to whom ? CALLY CALL EJB2EMOVE
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
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
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
DSSHQGL[$
(spec: 450)
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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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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 have ynohaclve no view, so theient security home or cl n informatio
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
DSSHQGL[$
- isCallerInRole() can be called from business methods only
(spec: 90)
DSSHQGL[$ILQDOPRFNH[DP
27
7HICH TWO ARE TYPICALLY RESPONSIBLE FOR CREATING EJB JAR lLES #HOOSE TWO
28
7HICH OF THE FOLLOWING STATELESS SESSION BEAN CONTAINER CALLBACK METHODS TAKES AN ARGUMENT #HOOSE ALL THAT APPLY
(spec: 487)
R! 4HE BEAN PROVIDER R" 4HE APPLICATION ASSEMBLER R# 4HE DEPLOYER R$ 4HE SYSTEM ADMINISTRATOR
(spec: 77)
R! HME5HPRYH R" HME&UHDWH R# HME&UHDWH R$ HME3DVVLYDWH Context object on si es S a es ak t R% VHW6HVVLRQ&RQWH[W -
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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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
- it could also be a Collection
, 317)
32
7HICH ARE TRUE FOR A MESSAGE DRIVEN BEAN #HOOSE ALL THAT APPLY
(spec: 324-325
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\! 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´
DSSHQGL[$
(spec: 440)
DSSHQGL[$ILQDOPRFNH[DP
34
7HICH ARE VALID LOCAL HOME INTERFACES FOR A STATEFUL SESSION BEAN #HOOSE ALL THAT APPLY
(spec: 98)
R! SXEOLFLQWHUIDFH7HVW%HDQLPSOHPHQWV MDYD[HME(-%/RFDO+RPH^ Y RLGFUHDWH WKURZV&UHDWH([FHSWLRQ `
R" SXEOLFLQWHUIDFH7HVW%HDQH[WHQGV
Must: - throw CreateException - return local interface type - start with ÒcreateÓ - NOT throw RemoteException
MDYD[HME(-%/RFDO+RPH^ 7 HVW%HDQ/RFDOHME&UHDWH WKURZV&UHDWH([FHSWLRQ `
R# SXEOLFLQWHUIDFH7HVW%HDQH[WHQGV MDYD[HME(-%/RFDO+RPH^
7HVW%HDQ/RFDOFUHDWH WKURZV&UHDWH([FHSWLRQ
`
R$ 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
\RXDUHKHUH
PRFNH[DPDQVZHUV
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 le, s must have a sing es el at st R$ "OTH STATEFUL AND STATELESS SESSION BEANS CAN SUPPORT OVERLOADED arg ejbCreate µHME&UHDWH¶METHODS
no-
R% "OTH STATEFUL AND STATELESS SESSION BEANS CAN IMPLEMENT THE- only stateful
38
ve state, - stateless iecantn -haspeciÞc R& "OTH STATEFUL AND STATELESS SESSION BEANS CAN HAVE INSTANCE VARIABLE STATE just not cl state ) 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 n b eeded as of E J B 2 .0 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
DSSHQGL[$
(API docs)
DSSHQGL[$ILQDOPRFNH[DP
40
(OW MANY JAVAXEJB%*",OCAL(OME INTERFACE METHODS CAN BE CALLED WITHOUT AN EXCEPTION FROM A SESSION BEAN CLIENT
R! R" R# R$ 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!
\RXDUHKHUH
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
R! MDYD[WUDQVDFWLRQ7UDQVDFWLRQ R" MDYD[WUDQVDFWLRQ8VHU7UDQVDFWLRQ R# MDYD[WUDQVDFWLRQ6\QFKURQL]DWLRQ R$ MDYD[WUDQVDFWLRQ7UDQVDFWLRQ0DQDJHU
DSSHQGL[$
(spec: 332)
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
\RXDUHKHUH
PRFNH[DPDQVZHUV
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 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 getEJBLo
calHome()
DSSHQGL[$
- system exceptions are always logged
DSSHQGL[$ILQDOPRFNH[DP
54
)N WHAT SCENARIOS CAN A BEANS BUSINESS METHOD CALL THE LV&DOOHU,Q5ROH METHOD OF THE 3ESSION#ONTEXT INTERFACE #HOOSE ALL THAT APPLY
Transaction demarcation
R! ! STATEFUL SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCA doesnÕt matter here TION
R" ! STATELESS SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCA TION
R# ! STATEFUL SESSION BEAN WITH BEAN MANAGED TRANSACTION DEMARCATION R$ ! 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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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 #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
R% 3%,%#4 $)34).#4 /"*%#4 C
&2/- #USTOMER C /RDER O
7(%2% CCUSTNUM OCUSTNUM
DSSHQGL[$
- not a Customer type - doesnÕt guarantee you wonÕt get duplicates
(spec: 232)
DSSHQGL[$ILQDOPRFNH[DP
59
'IVEN 0 HWKRG 7[ !0HWKRG 7[ !0HWKRG 7[
(spec: 357-359)
?!0HWKRG 7[ )F THE CALLING METHOD IS ON THE LEFT SIDE OF AN ARROW AND THE CALLED METHOD ON THE RIGHT WHICH SET OF TRANSACTION ATTRIBUTES WILL SUPPORT THE TRANSACTION SCOPE SPECIlED #HOOSE ALL THAT APPLY
R! 0 1HYHU
0 6XSSRUWV
0 5HTXLUHG
0 5HTXLUHV1HZ
a 1 could not Nbeeviner d ho et M . R E V E as N w - Never meannsif...its transaction attribute io t ac trans
R" 0 5HTXLUHG
0 6XSSRUWV
0 0DQGDWRU\
0 5HTXLUHV1HZ
R# 0 5HTXLUHV1HZ
0 5HTXLUHV1HZ
0 6XSSRUWV
0 5HTXLUHV1HZ
R$ 0 5HTXLUHG
60
0 0DQGDWRU\
0 6XSSRUWV
0 6XSSRUWV
tion, but 1Õs transacra d ho et m in g in nn t nsaction - method 2Reqis uiruresNew, it would be a new if it had
- method 4 starts a does not have Supportsnew transaction, so it obviously as an attribute
(spec: 229)
'IVEN THE %*" 1, EXPRESSION SGLVFRXQW127%(7:((1$1' 7HICH EXPRESSION IS EQUIVALENT
- 10 and 15 a
re EXCLUDE
D
R! SGLVFRXQW 25SGLVFRXQW! R" SGLVFRXQW 25SGLVFRXQW! R# SGLVFRXQW 25SGLVFRXQW! R$ SGLVFRXQW 25SGLVFRXQW!
\RXDUHKHUH
PRFNH[DPDQVZHUV
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
DSSHQGL[$
(spec: 372-373) They are intended to be handled by the client
DSSHQGL[$ILQDOPRFNH[DP
65
7HICH CASES CAN CAUSE A SESSION BEAN INSTANCE TO BE DESTROYED WITHOUT THE CONTAINER CALLING HME5HPRYH #HOOSE ALL THAT APPLY
(spec: 79)
R! ! TRANSACTION IS ROLLED BACK ON A STATEFUL SESSION BEAN WITH CONTAINER MANAGED TRANSACTION DEMARCATION
R" ! SYSTEM EXCEPTION IS THROWN FROM A BUSINESS METHOD R# !N INACTIVE CLIENT IS TIMED OUT WHILE THE BEAN IS IN A PASSIVATED STATE R$ 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
\RXDUHKHUH
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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
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FPU¿HOG!
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FPU¿HOG!
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R# UHODWLRQVKLSUROHVRXUFH!
DVVXPHPDQGDWRU\UHODWLRQVKLSUROHVRXUFHHOH PHQWVLQVHUWHGKHUH!
FPU¿HOG!
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!
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le source
-canÕt be in a ro
DSSHQGL[$ILQDOPRFNH[DP
70
(spec: 383)
7HATS TRUE ABOUT A REMOTE CLIENTS VIEW OF EXCEPTIONS RECEIVED FROM AN ENTITY BEAN #HOOSE ALL THAT APPLY
- only if the callerÕs tion was rolled ALWAYS ISSUE A MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5ROOHGEDFN([FH transac opposed to (as back SWLRQ EXCEPTION suspended)
R! )F THE CONTAINER MARKS A TRANSACTION FOR ROLLBACK THE CONTAINER WILL
R" )F THE CLIENT RECEIVES A MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5ROOHG
%DFN([FHSWLRQ THE CONTAINER GUARANTEES THAT THAT TRANSACTION WILL NEVER COMMIT
the
happens with R# ! MDYD[WUDQVDFWLRQ7UDQVDFWLRQ5HTXLUHG([FHSWLRQ EXCEP -Mandat ory tx attribute TION INFORMS THE CLIENT THAT THE BEAN NEEDED TO BE CALLED WITHIN THE CONTEXT OF A TRANSACTION
R$ )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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Index Symbols
607 574
384, 394, 406
449
460
449
503
582
393
505
384
505, 579
388
574, 578
388
504, 579
388
388, 422
502
385
449
395
615
610, 611
614
610
613
610
613
610
613
616
388
610
388
589
388
574
607
591, 592
607
591
607
589 this is a new appendix 685
the index
574
architectural overview 63
476, 502, 504
arguments 67
476, 502
Atomic 472
574, 581
attributes. See transaction attributes authentication 572 authorization 572
A
Auto-acknowledge 460
abstract getter and setter 313
B
abstract persistence schema 384, 387
Bean-managed transactions. See BMT
abstract schema type 408
beanness 188, 191, 196
ACID test 472
beans 11. See also entity beans; See also message-driven beans; See also session beans
abstract 313 abstract getters and setters 315, 383
acknowledgement. See message acknowledgement actor playing an entity 350 administered object 616 Advice Guy bean 15 afterBegin() 512 afterCompletion() 512 Application 33 making a new J2EE app in the deploytool 33
bean inheritance 186 five things you do to build a bean 16 overview 98 bean creation 188, 192, 194, 196. See also entity beans bean getting shot 283 Bean Provider 26 exception responsibilities 541
Application Assembler 26
passivation responsibility for stateful session beans 203
Application Assembler’s responsibility
responsibility for the Deployment Descriptor 617
615
security responsibilities 589
deployment descriptor 617
writing a CMP entity bean 313
security 574, 588
writing a message-driven bean 447
Application exceptions 532
beat box. See also appendix A
application exceptions 500, 548
beforeCompletion() 512
686
index
the index begin() 476, 478 Being John Entity Bean 350 BETWEEN 416. See EJB-QL BMP 303 BMT 476, 478, 482, 485, 487, 490, 502, 508 getStatus() 489 restrictions 481 summary of bean-managed demarcation 508 bodyguard 94 bullet points 166 architectural overview 97 client view 131 EJB-QL 420 entity client view 287 entity relationships 420 exceptions 555 local interfaces 166 overview 14 Remote interfaces 144 RMI 76 session bean lifecycle 221 business interface 79 business methods 199, 226
C cascade-delete 387, 388 cast 120 narrow before cast 120 client 55 client Code 57, 219 client view 111 component interface 136 exceptions 159 local 145 code example 119 creating a test client 55 InitialContext 117 local client code 160 lookup 116 Client before and after message-driven beans 441 client Jar 51 client view 111, 131 EJBHome methods 129 EJBObject methods 137 entity bean 287 exceptions 159 local 145 local interface code 156 CMP 302 vs. BMP 303 CMR 383, 396. See also cascade-delete cmr-field 387 you are here4
687
the index
CMR field 383, 386
chapter 4: session beans 244
CMT 476, 482, 485, 487, 499, 502, 509
chapter 5: entity bean client view 288
summary of container-managed transactions 509
chapter 6: entity bean synchronization 362
CMT. 491
chapter 7: entity relationships and EJB-QL 425
code examples
chapter 8: message-driven beans 463
AdviceStatefulBean code 218 client 119
chapter 9: transactions 516 commit 471, 473
AdviceStatefulBean client 219
commit() 478
exceptions in client interfaces 538
commit options 356
CMP entity bean complete 318 CustomerBeanCMP 318
equals() vs. isIdentical() 150
Customer BMT entity bean 268
Remote vs. local interfaces 154
Customer CMT entity bean 316
compiling a bean 30
entity bean Remote home interface 275
component-based development 3
exceptions in client interfaces 538
component interface 87, 133, 234, 271, 272
local client code 160
implementing 87
local client interfaces 156
confusingly-named exceptions 554
message-driven beans 446
Consistent 472
MovieBean CMP code 396
constructor 195, 196
MovieHomeRemote interface 398
container 6
Remote home interface 126
container-managed persistence. See CMP
WelcomeBean 446
container-managed relationship. See CMR
Coffee Cram appendix A: final mock exam 637
Container-managed transactions. See CMT container callbacks 181, 310
chapter 1: overview 59
ejbActivate() 183
chapter 10: exceptions 563
ejbCreate() 181
chapter 11: security 593
ejbPassivate() 183
chapter 12: environment and programming restrictions 627
ejbRemove() 183
chapter 3: client view 168 688
compare
index
implementing in a session bean 183 setSessionContext() 183
the index Container responsibilities
abstract persistence schema 384
exceptions 546
abstract schema 394
create() 123, 232, 237
intro 23
entity vs. session bean 281
message-driven bean 449
CreateException 125, 548
resource manager connection factories 610
create methods 159, 181
transactions 502, 503, 504
creation
method parameters 505
entity beans 329
wildcard 579
entity vs. session bean 281
deploytool 32
session beans 188, 192
deserializing 71 Director 378
D database 301 database to entity mapping 400 DataSource 602, 610
Director talking to entity bean 284 distributed transactions 473 two-phase commit 473 DuplicateKeyException 548 Dups-ok-acknowledge 460 Durable 472 durable subscription 450
dead bean 284 entity vs. instance death 285
DELETE 265
E
deploy-time customization 602, 618
EJB
declarative security 572 declarative transactions. See CMT
Deployer 27
and RMI 81
deployment descriptor responsibilities 618
architectural overview 63
responsibilities for mapping abstract roles to people 583
EJBObject 82
deployment descriptor 615
ejb-jar 24, 620, 624 requirements 24 ejb-jar.xml 624 you are here4
689
the index
EJB-QL 401, 402, 411
EJBLocalObject 145, 156
AND 405
EJBMetaData 149
BETWEEN 416
EJBObject 82, 94, 133, 137
Collection types 413
ejbPassivate() 183, 200, 204, 207, 308, 314, 355
FROM clause 403
ejbPostCreate() 334, 396
identifiers 410
ejbRemove() 183, 210, 213, 214, 216, 314
IN operator for the FROM clause 415
missed ejbRemove() in session beans 213
IN with the WHERE clause 417
ejbStore() 314, 355
IS EMPTY 418
EJB 2.0 guarantees
IS NOT EMPTY 418
services and behavior 623
LIKE expression 419
supported APIs 621
parameters 405 path navigation 404 reserved words 410
EJB references 613 614 EJB Roles and Responsibilities 26
SELECT clause 403, 406
Application Assembler 26
String literals 417
Bean Provider 26
topics and queues 450
Deployer 27
using collections in a path 414
EJB security mapping 590
WHERE 412
EntityBean 312, 314
WHERE clause 403, 411
entity beans 99
ejb-relation 387
activation 352, 354
ejb-relationship-role 387
actor playing an entity 350
ejbActivate() 183, 200, 204, 207, 308, 314, 354
business method 348
EJBContext 477
client view 287
ejbCreate() 181, 195, 196, 237, 331, 333
CMP bean construction 326, 327
EJBException 537, 539, 552, 558
CMP bean creation 328, 338
EJBHome 128 methods 129
ejbCreate() 331, 333 ejbPostCreate() 334
ejbLoad() 314, 354
OID for bean creation 329
EJBLocalHome 145
CMP class example 316
690
index
the index CMP complete class code 318
exam objectives
container callbacks 310, 312
bean environment 600
ejbActivate() 308
client view 112
ejbPassivate() 308
EJB overview 2
ejbPostCreate() 396
entity bean client view 260
entity realization (how a bean becomes an entity) 306
entity bean lifecycle 296
entity vs. instance death 285 finder methods 276, 339, 341 home business method 345 home interface 273, 275 lifecycle 320 mapping from abstract schema to a real database 400
entity relationships: CMP and CMR 374 exceptions 526 message-driven beans 438 security 570 session beans 174 transactions 470 exceptions 555
overview 268
application exceptions 533, 548
passivation 308, 355
client interfaces 159
relationships 378
common system exceptions 551
unidirectional 391
CreateException 548
relationship assignments 421
DuplicateKeyException 548
remove() 282, 283, 284
EJBException 537, 539
session remove vs. entity remove 282
FinderException 538, 548
synchronization 298, 301
logging system exceptions 535
environment
ObjectNotFoundException 548
creating a subcontext 609
RemoteException 78, 133, 537
resource mapping 612
RemoveException 548
subcontexts 604
scenarios 556
environment entries 607
system exceptions 534
scope 608
exception pathways 530
types 608
exception scenarios 556
equals() 150
Exercise. See Sharpen your pencil exotic casting 122. See narrow you are here4
691
the index
F
H
findByPrimaryKey() 274
Handle 139, 149
FinderException 538, 548, 559
handle 149
finder methods 274, 276, 339, 341
home 91
Container writes all the code 342
business methods 278
FROM 411
create() 123 EJBHome 128 home interface 114
G
methods 129 home business method 278, 345 home interface 273
getCallerPrincipal() 241, 587
EJBHome 128
getEJBHome() 137, 241
entity bean Remote home interface 273, 279
getEJBLocalHome() 241
methods 129
getEJBLocalObject() 241 getEJBMetaData() 129
rules 125 home object 91
getEJBObject() 241 getHandle() 137
getRollbackOnly() 241, 488, 500
I
getStatus() 489
IIOP 90
getUserTransaction() 241, 476, 477, 478
IllegalStateException 551, 552, 558, 560
getHomeHandle() 129 getPrimaryKey() 137
IN. See EJB-QL inheritance 186 InitialContext 117 input parameters 412. See EJB-QL INSERT 265 692
index
the index instance-level security 586 interface business interface 79 comparing Remote vs. local 154, 163 component interface 82, 133, 271 EJBHome 129 EJBObject 137 extending 85 home interface 91, 114, 125, 273 javax.ejb.EntityBean 182 javax.ejb.EntityContext 182 javax.ejb.MessageDrivenBean 182 javax.ejb.MessageDrivenContext 182 javax.ejb.SessionBean 182 javax.ejb.SessionContext 182 local client interfaces 145, 166 exceptions 159 Remote 78 squeamish about not implementing 86 isCallerInRole 587 isCallerInRole() 587 isCallerInRole(String s) 241 isIdentical 141 isIdentical() 142 isIdentical(Object o) 137 Isolated 472 IS EMPTY. See EJB-QL IS NOT EMPTY. See EJB-QL
J J2EE Reference Implementation (RI) Client Jar 51 deploytool 32 JNDI name 52 New Enterprise Bean Wizard 37 server 31 verifier 47 java.net.Socket 625 java:comp/env 602, 603 subcontexts 604 JavaMail 621 javax.ejb.EJBContext 477 javax.ejb.EntityBean 312. See also EntityBean javax.ejb.SessionBean 182. See also SessionBean javax.ejb.SessionSynchronization 511 javax.jms.QueueConnectionFactory 611 javax.jms.Topic 449 javax.jms.TopicConnectionFactory 611 javax.mail.Session 611 javax.transaction.UserTransaction 471, 477 JAXP 621 JDBC 621 JMS 452, 621 JNDI 92, 602 bean’s special context 189, 602 InitialContext 117, 602 lookup 116 you are here4
693
the index
narrow the result 120
JMS 452
JNDI API 1.2 621
lifecycle 445
JNDI name 52
MessageDrivenContext 455, 456
JTA 621
MessageListener 452
JTS 471
message acknowledgement 458, 460 queues 454 rules for writing the class 448
L
topics 453 transaction attribute 500 MessageDrivenContext 455, 456
LIKE expression EJB-QL. See EJB-QL local client view 145 local interface 148, 156 exceptions 159 vs. Remote interface 154 locking (database) 301 logging 535 lookup 116
MessageListener 452 message acknowledgement 458 methods afterBegin() 512 afterCompletion() 512 beforeCompletion() 512 begin() 476 create() 128, 274 create methods 159 ejbActivate() 183, 200, 204, 207, 309, 354
M
ejbCreate() 183, 195, 331, 333
Mandatory 492
ejbPostCreate() 334
Many-to-Many 380
ejbRemove() 213, 214, 216
message-driven beans 106, 437, 442
findByPrimaryKey() 274
ejbLoad() 354 ejbPassivate() 183, 200, 204, 207, 309
BMT 460
getCallerPrincipal() 587
CMT 460, 500
getEJBHome() 137
concurrent processing 444
getEJBMetaData() 129 getHandle() 137
694
index
the index getHomeHandle() 129 getPrimaryKey() 137 getRollbackOnly() 488 getStatus() 489 getUserTransaction() 476 isIdentical(Object o) 137, 141 remove() 137, 282 remove(Handle h) 129 remove(Object key) 129 remove methods 159 setRollbackOnly() 485 setSessionContext() 183
N narrow 120 PortableRemoteObject.narrow() 121 network transparency 65, 66 Never 492, 495 NoSuchEntityException 551, 552 NoSuchObjectException 551, 553 NoSuchObjectLocalException 551, 552, 553 NotSupported 492, 495 NOT IN. See EJB-QL
setSessionContext(SessionContext sc) 195 method permissions 578 581 union 580
O
missed ejbRemove() in session beans 213, 215
objectives. See exam objectives
mock exam. See Coffee cram
ObjectNotFoundException 548, 553, 559
Movie 378
ome business method 346
MovieBean code 396
One-to-Many 380
MovieHomeRemote interface 398
One-to-One 380
MovieSchema 408 multiplicity 380, 387, 422 affects return type 382 Many-to-Many 380 One-to-Many 380 One-to-One 380
P passing objects remotely 68 passivation stateful session bean 200 transactions 206 you are here4
695
the index
pass by copy 69 pass by reference 68 path navigation 404 persistent field 313 virtual 315 point-to-point 451. See also queue; See also topic PortableRemoteObject.narrow() 121 primary key 332, 333 Principal 584 programmatic security 586, 589 programmatic transactions. See BMT programming restrictions 625 propagation transactions 474, 482 proxy. See stub publish/subscribe 451
R relationships 378, 394 unidirectional 391 relationship assignments 421 Remote 65 arguments 67, 72 Serializable 72 business interface 79 component interface 82 home interface 125 interface 78 PortableRemoteObject.narrow() 121 RemoteException 78 return values 67, 72 Serializable 72 vs. local interface 154
Q
RemoteException 78, 133, 537, 559
queries 406. See EJB-QL
Remote interface 78, 144
Remote home interface 125, 279 EJBHome 128
queues 450, 454
component interface 82, 137, 271 home interface 125 EJBHome 128 vs. local interface 154 Remote Method Invocation 63, 64 Remote object 65, 67 EJBObject 82 remove 129, 151, 159, 282
696
index
the index entity beans 284
rollback() 478
entity vs. session bean 282, 283
RPC 67
remove() 137, 151, 208, 282, 286 entity vs. session bean 283
run-as 591 RuntimeException 545
remove(Handle h) 129 remove(Object key) 129 RemoveException 548, 559 remove methods 159 Required 492 RequiresNew 492 resource manager connection factory 610 resource authorization 611 return values 67 Serializable 72 RMI 63 arguments 67 how its used by EJB 81 IIOP 90 PortableRemoteObject.narrow() 121 RemoteException 78 Remote object 65 return values 67 RMI-IIOP 90 rmic 90 skeleton 65, 67 stub 64 rmic 90 Role 584 role reference 589 rollback 473
S scalable stateless session beans 103 security App Assembler 574, 576 authentication 572 authorization 572 context propagation 592 declarative security 572 Deployer 583 identity 591 instance-level security 586 isCallerInRole() 587 Principal 584 programmatic security 586 roles 574 role definition 576 security identity 592 security mapping 590 security roles 574, 576 578 SELECT 265, 402, 406 you are here4
697
the index
Serializable 67, 72
setSessionContext(SessionContext sc) 195
server 31
Sharpen your pencil
Server dude at the pool 441
APIs 621
SessionBean 182, 183
architectural overview 107
SessionContext 189, 199, 240, 241
bean table 108
SessionSynchronization 511, 512
bean types 13
callbacks 512 session beans 182
client view exercise 165 CMP entity creation 359
bean lifecycle 180, 184
compiler checked? 447
container callbacks 182
EJB-QL 407
implementing 183
EJB architecture 10, 80
missed ejbRemove() calls 215
EJB Lifecycle 96
overview 98, 100
EntityBean interface 323
passivation 200, 207
entity bean 280
removal 208, 210
entity bean callbacks 353
scalability 103
entity bean class methods 361
SessionBean interface 182
entity bean relationships (Director-to-Movie) 390
stateful session beans 178, 184
entity business method 360
creation 179, 192, 196 OID for bean creation 194
entity CMP code annotation 319 entity lifecycle activity 324
passivation/activation 207
environment 626
removal 210
exceptions 561
stateless session bean 102, 222 creation OID for bean creation 227
exception exercise 562 exception scenarios 557 home interface 132
session context 240
local and Remote client interfaces 155
setEntityContext(EntityContext ec) 314
local clients 158
setRollbackOnly() 485, 487
local client view 147
setRollbackOnly(boolean b) 241
message-driven bean 461
setSessionContext(SessionContext ctx) 183
message-driven bean context methods 455
698
index
the index Multiplicity and Assignments 423
supported APIs 621
package name 119
Supports 492, 495
security roles 575
suspended transactions 483
SessionBean interface 186
synchronization 298
session bean overview 104
system exceptions 500, 551
stateful session bean state diagram 187
logging 535
stateless to stateful 220 transactions 480 transactions puzzle 514 transaction attributes 496, 497, 507 UserTransaction 484 write an entity bean 317 skeleton 65, 67 squeamish 86 stateful session bean 178 creation 179, 194, 196 Object Interaction Diagram (OID) for bean creation 194
T The Advice Guy 15 Tikibean Lounge BMT/CMT 501 EJBObject/bean 89 session bean/bartender 14 topics 450, 453 durable subscription 450
removal 210
topics and queues 450
SessionSynchronization 512
TransactionRequiredException 551, 552
stateless session transactions in 481 stateless session bean 102, 222 business methods 226 creation 224 Object Interaction Diagram (OID) for bean creation 227
TransactionRequiredLocalException 551, 552 TransactionRolledbackException 551, 552 TransactionRolledbackLocalException 551, 552 transactions 471, 473. See also commit; See also rollback; See also setRollbackOnly() Bean-managed transactions 476 begin() 476
String literals. See EJB-QL
BMT 476, 481
stub 64, 67
call stack example 479
subcontexts 604
database locking 301
you are here4
699
the index
deployment descriptor 503 getRollbackOnly() 488, 500
UserTransaction 476, 477 getStatus() 489
message-driven beans 460, 500 propagation 474, 482 SessionSynchronization 512 stateful session bean passivation 206 suspension 475, 483 transaction attributes 492 two-phase commit 473 unspecified transaction context 499
V vendor lock-in 5 verifier 47 virtual persistent fields 315
transaction attributes 492, 493, 498 attributes that require a transaction 494
Never 492, 495
W
NotSupported 492, 495
WHERE 403, 411, 412
Required 492
wildcard
Mandatory 492
RequiresNew 492
method elements 504
Supports 492, 495
transaction attributes 504
Tutorial 28 two-phase commit 473
U unidirectional 391 unsetEntityContext() 314 unspecified transaction context 499 UPDATE 265 Users 584 700
index
Interface summary javax.ejb.EJBContext getCallerPrincipal() getEJBHome() getEJBLocalHome() getRollbackOnly() getUserTransaction() isCallerInRole(String role) setRollbackOnly()
javax.ejb.EntityContext
javax.ejb.SessionContext getEJBLocalObject() getEJBObject()
getEJBLocalObject() getEJBObject() getPrimaryKey()
javax.ejb.MessageDrivenContext // adds no methods
java.rmi.Remote // no methods declared
javax.ejb.EJBHome getEJBMetaData() getHomeHandle() remove(Handle h) remove(Object PK)
javax.ejb.EJBObject getEJBHome() getHandle() getPrimaryKey() isIdentical(EJBObject o) remove()
javax.ejb.EJBLocalHome
javax.ejb.EJBLocalObject
remove(Object PK)
getEJBLocalHome() getPrimaryKey() isIdentical(EJBLocalObject o)
Interface summary java.io.Serializable // no methods declared
javax.ejb.Handle
javax.ejb.EnterpriseBean // no methods declared
getEJBObject()
javax.ejb.EntityBean ejbActivate() ejbLoad() ejbPassivate() ejbRemove() ejbStore() setEntityContext (EntityContext ctx) unsetEntityContext()
javax.ejb.HomeHandle getEJBHome()
javax.ejb.MessageDrivenBean
javax.ejb.SessionBean ejbActivate() ejbPassivate() ejbRemove() setSessionContext (SessionContext ctx)
ejbRemove() setMessageDrivenContext (MessageDrivenContext ctx)
Interface summary
javax.ejb.SessionSynchronization
javax.transaction.UserTransaction begin() commit() getStatus() rollback() setRollbackOnly() setTransactionTimeout(int seconds)
am... ut() is not on thfoereexthe eo im T on ti ac ns ra tT se e elapsed time be it lets you tunedeth ansaction has timed tr e th d ci de r ne Contai rolls it back. out, and automatically
afterBegin() afterCompletion( boolean committed) beforeCompletion()
javax.jms.MessageListener onMessage(Message message)
