Using and Understanding Java Data Objects

444 Pages·2003·10.099 MB·English

by  David Ezzio (auth.)

Using and Understanding
Java Data Objects
DAVIDEZZIO
atft
APress Media, LLC
Using and Understanding Java Data Objects
Copyright.© 2003 by David Ezzio
Originally published by Apress in 2003
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopying, recording, or by any information
storage or retrieval system, without the prior written permission of the copyright owner and
the publisher.
ISBN 978-1-59059-043-0 ISBN 978-1-4302-0767-2 (eBook)
DOI 10.1007/978-1-4302-0767-2
Trademarked names may appear in this book. Rather than use a trademark symbol with every
occurrence of a trademarked name, we use the names only in an editorial fashion and to the
benefit of the trademark owner, with no intention of infringement of the trademark.
Technical Reviewers: Regis Le Brettevillois, John Mitchell, Abe White
Editorial Directors: Dan Appleman, Gary Cornell, Martin Streicher,
Karen Watterson, John Zukowski
Assistant Publisher: Grace Wong
Project Manager: Tracy Brown Collins
Copy Editor: Ami Knox
Production Editor: Julianna Scott Fein
Composition: Susan Glinert
lndexer: Valerie Robbins
Proofreader: Elizabeth Berry
Cover Designer: Kurt Krames
Production Manager: Kari Brooks
Manufacturing Manager: Tom Debolski
The information in this book is distributed onan "as is" hasis, without warranty. Although every
precaution bas been taken in the preparation of this work, neither the author(s) nor Apress shall
have any liability to any person or entity with respect to any loss or damage caused or alleged to
be caused directly or indirectly by the information contained in this work.
The source code for this bookis available to readers at http: 1/ 'IMtl.apress.com in the
Downloads section.
This book is dedicated to my wife, Theresa,
and our daughters, Pearly and Sarah.
A man is a fish who swims in the sea ofa woman's love.
Contents at a Glance
About the Author ................................................................................................. xi
About the Technical Reviewers .................................................................. xiii
Acknowledgments ...................................................................................................x v
Introduction ...................................................................................................... xvii
Chapter 1 Basic Concepts in JDO .......................................................... 1
Chapter 2 Queries ........................................................................................ 37
Chapter 3 The Persistence Manager .................................................... 75
Chapter 4 Transactions and Caching ................................................ 103
Chapter 5 Enhanced Classes and Managed Fields ........................ 143
Chapter 6 Factories That Produce
Persistence Managers ........................................................ 185
Chapter 7 Helpers, Callbacks, and Exceptions .......................... 227
Chapter 8 Using JDO to Learn More .................................................. 269
Chapter 9 Using JDO in a Swing Application .............................. 301
Chapter 10 Using JDO in a Web Application ................................... 321
Chapter 11 Using JDO in Enterprise JavaBeans ............................ 359
Glossary ............................................................................................................... 377
Appendix Large UML Diagrams ............................................................ 387
Index ...................................................................................................................... 403
v
Contents
About the Author ..........................................................................................
xi
About the Technical Reviewers ......................................................
xiii
Acknowledgments .............................................................................................
xv
Introduction .................................................................................................
xvii
Chapter Basic Concepts in JDO .................................................
1 1
The Persistence Services of JDO ................................................................. 3
Managed and Unmanaged Objects ..................................................................... 7
The Ten Management States of Data Objects ......................................... 17
Identity and the Uniqueness Requirement .............................................. 21
Sununary ................................................................................................................... 36
Chapter 2 Queries ................................................................................... 37
The Extent Interface ....................................................................................... 37
The Design of JDO, s Query Service ........................................................... 41
The Query Interface ......................................................................................... 41
Factory Methods That Produce Query Objects ....................................... 48
The Syntax of the JDO Query Filter .................................... ~ ................... 49
Query Variables .................................................................................................. 55
Ordering Results ................................................................................................ 60
Using or Ignoring the Cache in a Query ................................................ 62
SQL Queries That Can Be Mapped to JDOQL .............................................. 64
Using SQL When JDOQL Is Not Sufficient ................................................ 71
How JDO and JDOQL Help the Development Process .............................. 72
Summary ................................................................................................................... 73
vii
Contents
Chapter 3 The Persistence Manager .......................................... 75
The Handling of null Values in Method Parameters .......................... 76
Obtaining and Closing a Persistence Manager ..................................... 77
Controlling JDO's Management of Data Objects ...................................
78
Controlling the Cache .....................................................................................
89
Getting and Constructing Identity Objects .........................................
95
Fetching an Application Data Object by Identity ............................ 97
Factory Methods in the Persistence Manager .......................................
98
Getting the Persistence Manager's Transaction .................................
98
The Properties of a Persistence Manager .............................................. 99
Summary ..................................................................................................................
101
Chapter 4 Transactions and Caching ..................................... 103
Transactions .......................................................................................................
104
JDO's Transaction Interface ...................................................................... 108
How the Transactional Properties
Control State Transitions ...................................................................
122
The Optional Transient-Transactional Feature .................................
133
JCA, JTA, and JDO Transactions ...............................................................
135
JDO' s Cache of Persistent Objects and Their State ......................
137
Summary ..................................................................................................................
141
Chapter 5 Enhanced Classes and Managed Fields ......... 143
Which Application Classes Should Be Enhanced? ...............................
143
Managed and Unmanaged Fields .................................................................... 144
Enhancement ......................................................................................................... 148
The JDO Metadata .............................................................................................. 166
Summary ..................................................................................................................
182
Chapter 6 Factories That Produce
Persistence Managers ................................................ 185
The PersistenceManagerFactory Interface ............................................
185
Obtaining a Persistence Manager ............................................................. 186
Obtaining a Persistence Manager Factory ............................................
188
Closing a Persistence Manager Factory ................................................ 194
Obtaining a Connection Factory ...............................................................
195
Examining a JDO Implementation ...............................................................
195
viii
Contents
Configuring a Persistence Manager Factory ....................................... 198
Configuring Connections to the Datastore ......................................... 198
JDO's Support for Container-Managed Transactions ........................ 199
JDO's Support for Bean-Managed Transactions ................................... 201
Using JDO in CMT Session Beans ............................................................... 201
On Returning Serialized Data Objects
from Business Methods ............................................................................ 208
Using JDO in Entity Beans with BMP ...................................................... 209
Using JDO in BMT Session Beans ............................................................... 220
Using JDO in Message-Driven Beans ......................................................... 225
Summary ................................................................................................................. 225
Chapter 7 Helpers, Callbacks, and Exceptions ........... 227
The JDOHelper Utility Class ...................................................................... 227
The InstanceCallbacks Interface ............................................................. 234
The Exceptions of JDO ................................................................................... 249
Summary ................................................................................................................. 267
Chapter 8 Using JDO to Learn More ........................................ 269
The Ant Build Scripts ................................................................................... 270
Getting Started ................................................................................................ 271
Hello, JDO! ......................................................................................................... 276
Interrogating the PersistenceManagerFactory ................................... 278
Consuming Java at the MegaCups Company .............................................. 280
The Console User Interface ........................................................................ 283
Querying the Small Town Library ............................................................. 284
Monitoring the State of Persistent Apples ....................................... 289
Using the Commercial Implementations .................................................. 298
Summary ................................................................................................................. 300
Chapter 9 Using JDO in a Swing Application ................. 301
Building the Rental Swing Application ................................................ 301
Requirements for the Prototype Reservation System ...................... 302
Testing the Rental Swing Client ............................................................. 306
Encountering Conflicting Changes in the
Rental Swing Client ................................................................................ 308
Designing the Rental Swing Application .............................................. 310
Summary ................................................................................................................. 319
ix
Contents
Chapter 10 Using JDO in a Web Application ...................... 321
Configuring the Build Environment for Tomcat ................................. 321
Building the Rental Web Application .................................................... 323
Using the Rental Web Application ........................................................... 325
General Design Issues for Web Applications ..................................... 332
The MVC Pattern in the Rental Web Application ............................... 333
Designing the Use of JDO in a Web Application ............................... 334
The One-PM-per-Request Design .................................................................. 339
The One-PM-per-Session Design .................................................................. 354
The One-PM-per-Update Design .................................................................... 355
Summary .................................................................................................................. 357
Chapter 11 Using JDO in Enterprise JavaBeans .............. 359
Configuring the Build Environment for JBoss ................................... 360
Building the Rental Enterprise Application ..................................... 365
Design of the Rental Enterprise Application ................................... 367
Using JDO with other Types of EJBs ....................................................... 373
Summary .................................................................................................................. 375
Glossary ............................................................................................................ 377
Appendix Large UML Diagrams ..................................................... 387
Index .................................................................................................................... 403
X
About the Author
David Ezzio wrote his first application, which
analyzed French elections, for a college professor
in the sixties. After a detour through philosophy
and other pursuits, he has worked with software
teams building desktop applications, character
recognition software, and Internet-related software.
He has worked exclusively with Java since 1997 and
is a Sun Certified Java Developer. Dave founded his
consulting practice, Yankee Software, in 1988 and
helped found MaineJUG in 2001. He is a member of
the JDO 1.0 maintenance group.
Dave holds a bachelor's degree in mathematical logic from Yale University and
a master's degree in philosophy from the University of Chicago. In his free time,
Dave hikes, rides his bicycle, reads history, and sails his Laser Tipp ity. An occasional
cook, he currently takes pride in his popovers. He lives in Maine. His e-mail
address is dezzio@ysoft. com.
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