Java 2 Enterprise edition Bible

705 Pages·2002·3.11 MB·English

by  Justin Couch, Daniel H Steinberg

Java 2 Enterprise Edition Bible
Justin Couch and Daniel H. Steinberg
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About the Authors
Justin Couch has been a professional Java programmer since early 1996 and hasn't looked back
since. His travels have taken him through all realms of the Java world — from writing parts for the
VRML specification (leading working groups and authoring the External Authoring Interface) to the
IETF — working on the URN specifications. The applications realm he has worked on has gone
through a similar wide variety — from mobile distributed applications to large-scale Web site
hosting and electronic display systems. His main programming interests are virtual reality and the
distributed systems required to run them. He currently runs the Java 3D community site
(http://www.j3d.org/) and the Java 3D Programmers FAQ (http://www.j3d.org/faq/). When not
programming Justin's interests are music (classical and electronic), gliding, and attempting to shorten
his life by riding motorcycles.
Daniel H. Steinberg is the director of Java Offerings at Dim Sum Thinking. A trainer and
consultant, he has been teaching and writing about Java since 1996. Daniel has covered Java on the
Macintosh for JavaWorld magazine and the O'Reilly Network's Mac DevCenter. He managed the
Mac FAQ at jGuru and served as editor of developerWorks Java Technology Zone and of the
CodeMasters Challenge for JavaWorld magazine. Although he does Java development for and on
platforms other than Mac OS X, he's happier on his Mac. Daniel has been working with Colleges and
Universities to help their faculty and students keep up with the quickly changing technology. His
current interests have led him to lead sessions in refactoring and extreme programming. Mostly
Daniel enjoys being a dad and hanging out with his wife, two daughters, and black Lab.
Uma Veeramani, author of Chapters 18 and 19, is a software programmer and member of the
technical staff at a security software company in Austin, TX. Her prior experience was as a Java
developer in the financial services industry. She has experience working on a number of platforms
and languages, including Java, ASP, C++, etc. Uma was a gold medallist at the University of
Madras, India, and graduated with degrees in physics and computer applications.
Bruce Beyeler, author of Chapter 22, is the owner of Arizona Software Insights, a Java consulting
and training company. Bruce has been consulting and training (corporate and collegiate) in Java for
over four years and has 15+ years of experience developing software systems. He specializes in
embedded systems, communications, and application integration. Bruce has led numerous projects
ranging from embedded applications to J2EE projects in a variety of industries such as aerospace,
automotive, telephony, and e-commerce. Bruce is currently working on his Ph.D. in computer
science at Arizona State University, where his emphasis is embedded systems and communications.
Mike Jasnowski, author of Chapter 23, is a senior software engineer at eXcelon Corporation in
Burlington, MA, and has XML and Java coming out of his ears. He works as leader of the project
that develops Web-based tools for administering eXcelon's Business Process Manager. He has been
involved with computers and software for over 18 years, dating back to the days before Java and
XML, when he wrote some of his first programs on a TRS-80 and Apple IIe. Mike has worked on a
variety of operating systems, including Multiple Virtual Storage (MVS), Linux, Windows, and
Virtual Machine (VM), in addition to a variety of programming languages. He worked for Sprint for
over nine years as a systems programmer and moved on to work in the healthcare and finance
industries as a software engineer before finally landing at eXcelon. He is the lead author of Java,
XML, and Web Services Bible (Hungry Minds, Inc., 2002), and he contributed three chapters to the
book Developing Dynamic WAP Applications (Manning Press, 2001). He's also written articles for
Java Developers Journal and XML Journal. He lives in Amherst, New Hampshire, with his wife
Tracy, his daughter Emmeline, and a host of pets.
To Alan, John, and Steve, for getting me into this mess and then getting me back out of it!
— Justin Couch
To Stephen Wong, for arguing with me every day for two years until I began to get it.
— Daniel H. Steinberg
Table of Contents
Java 2 Enterprise Edition Bible
Preface
Part I Getting Started
Chapter 1 -Defining the Enterprise
Chapter 2 -Introducing Enterprise Applications
Part II Delivering Content
Chapter 3 -Creating Dynamic Content with Servlets
Chapter 4 -Using JavaServer Pages
Chapter 5 -Sending and Receiving Mail with JavaMail
Part III Finding Things with Databases and Searches
Chapter 6 -Interacting with Relational Databases
Chapter 7 -Using JDBC to Interact with SQL Databases
Chapter 8 -Working with Directory Services and LDAP
Chapter 9 -Accessing Directory Services with JNDI
Part IV Communicating Between Systems with XML
Chapter 10 -Building an XML Foundation
Chapter 11 -Describing Documents with DTDs and Schemas
Chapter 12 -Parsing Documents with JAXP
Chapter 13 -Interacting with XML Using JDOM
Chapter 14 -Transforming and Binding Your XML Documents
Part V Abstracting the System
Chapter 15 -Exploring the RMI Mechanism
Chapter 16 -Introducing Enterprise JavaBeans
Chapter 17 -Using Advanced EJB Techniques
Chapter 18 -Introducing CORBA
Chapter 19 -CORBA Applications in the Enterprise
Chapter 20 -Why Dream of Jini?
Part VI Building Big System
Chapter 21 -Implementing Web Services
Chapter 22 -JMS
Chapter 23 -Managing Transactions with JTA/JTS
Chapter 24 -System Architecture Issues
Chapter 25 -J2EE Design Patterns
Appendix A -Installing the J2EE Reference Implementation
Appendix B -J2EE API Version Requirements
Appendix C -J2EE Vendors and Systems
Glossary
Index
Preface
Welcome to Java 2 Enterprise Edition Bible. This book, which is a follow−up to Java 2 Bible, is for readers
who wish to know more about the enterprise market. Enterprise programming is a hot topic these days, as
more and more companies decide they need an online presence to complement their existing
bricks−and−mortar version. This online presence is more than just a couple of Web pages; it extends to a
complete electronic catalogue and purchasing system.
XML is one of the biggest drivers of the enterprise market. As companies are starting to realize they need to
work together to smooth out the supply−chain management, they are building their second− or
third−generation systems. They are doing this in collaboration with their suppliers and partners. To build these
systems they need interoperability, and whole industries are springing up around this need alone. Need to add
a new partner or supplier? Just ask for the XML DTD. Very quickly you can now include the new
functionality in your system.
Throughout this book we will reference various commercial sites that you will be familiar with as examples of
how large−scale businesses are integrating not only their own Web sites, but also those of partners and
suppliers, into one single system. Order your computer from Dell and you can track it through every stage of
the build process. Then, once it has hit the courier, you can use the Dell site to trace the courier's information
about its progress. Dell doesn't use just one courier, either — yet your experience is identical regardless of
which one is used.
What this Book Aims to Do
The aim of this book is to introduce you to all the enterprise Java APIs. Many books are floating around that
deal with specific elements of the J2EE specification — Enterprise Java Beans and XML being the most
prevalent. Yet what these titles fail to address is the whole collection of other interfaces that you as a Java
programmer might find useful. For example, did you know that an API exists for e−mail and newsgroup
handling as part of J2EE?
As a programmer, I like to stay informed about all of the possible options. If I know about them, I can
investigate them further if they sound useful. If I don't know about them, I might be missing some very
important information that might have made my life much easier. Therefore, the aim of this book is to give
you as broad an understanding as possible of the APIs that can be useful in creating an enterprise−level
application. The primary focus is on the J2EE specification, but we also introduce other libraries where we
feel they will benefit your application.
We do not try to cover every topic in great depth. We leave that for other books. What we do is cover each
topic in sufficient detail that you can get started with simple programs and then know the right questions to
ask next. J2EE is a huge specification. If we were to cover it all in depth, you would need to cart the volumes
of the book on a trolley. No doubt you already have a bookshelf full of programming books and don't need a
lot more. Use this book as the introduction to all the parts of J2EE, and then consult other books that treat
specific areas of knowledge in depth.
Who this Book Is For
This book is aimed at the intermediate to advanced programmer. We assume that you already have some Java
programming under your belt. We don't spend any time introducing the programming language, and we
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Preface
assume you know how to compile and debug a Java application in your favorite development environment.
If you are looking for a beginner−level Java book then we can recommend the Java 2 Bible (ISBN
0−7645−4632−5) written by Aaron Walsh, Justin Couch, and Daniel H. Steinberg.
For the intermediate programmer, this book will introduce all the various technologies available to you as a
J2EE programmer. Perhaps you have never used J2EE before, so this book will show you where to start and
what order to approach your learning in.
For the more advanced programmer, this book can serve as a guide to expanding your horizon over the more
concentrated areas of programming. Use it as a guide to exploring more possibilities within the area that you
have already been working on, or new ways to address a problem. Finally, you can use it to learn about new
areas that you have not heard of before. Because of the breadth of J2EE, it is always possible that new topics
exist that you haven't heard of. Even after six−plus years of Java programming experience, I am constantly
finding new items popping up to learn about.
How to Use this Book
This book is divided into a number of parts. Each part is a self−contained area that focuses on just one piece
of the enterprise puzzle. Within each part, each chapter will stand alone if you know the underlying
technology.
Our approach is to cover all the parts of developing an enterprise application. That is, we don't follow just the
Java APIs, but introduce the fundamentals of the technology that Java operates on. We believe that for you to
be the best developer, you must have a solid understanding of the foundations. In fact, many of the enterprise
APIs demand it. If you don't understand how an XML document is structured, and the terms involved, you
will find it very hard to use the XML−parsing APIs, or to define how to load Enterprise Java Beans on your
Web server.
We recommend reading the parts of the book that are useful for what you need to do now. There is no need to
read it from cover to cover. If you haven't written an enterprise application before then we highly recommend
you look at Part I of the book. After that, feel free to roam to the sections that best suit your needs. If we need
another part of the book to help explain a piece of technology, we'll give you a cross reference to the
appropriate chapter.
This book is comprised of six parts that lead you from the front end of the system to the back end. Each part
covers a number of topics. We can summarize these parts as follows.
Part I: Getting Started
The introductory parts show you around the enterprise space and the various parts of the J2EE specification:
why you would want to use it, what constitutes an "enterprise" application, and some examples. The advanced
user can skip this part and head into the more specific chapters.
Part II: Delivering Content
Here we focus on the APIs that are used to deal with an external user — receiving input and sending output
back. It is all about presentation. Rarely is there application logic in these parts. They are more about
assembling pieces of pre−built logic into some correct order and then presenting the output to the user. More
2
Preface
often than not, the output is presented in a Web page, but (as you will see) there is more to this part than just
making a pretty Web site.
Part III: Finding Things with Databases and Searches
At the heart of every enterprise system is a database. In that database is a lot of information. In fact, so much,
that without having some form of search capability, you would find it almost impossible to do in anything else
with your application. The database has many forms other than the Oracle or MS Access that you are used to.
Specialized databases exist for many different purposes, and sometimes using Oracle alone is the wrong
solution.
Part IV: Communicating Between Systems with XML
As e−commerce systems become more and more complex, the ability to seamlessly talk between systems
becomes more important. It will be an extremely rare situation when you as the developer have to build the
complete end−to−end system. It is almost guaranteed that you will need to integrate third−party software into
the end product. The technology most commonly used for this purpose is XML. As a text−based structured
data format, it works wonderfully well for this. However, to make the most out of XML requires an awful lot
of knowledge, and so we devote an entire part of the book to learning everything about XML.
Part V: Abstracting the System
When system complexity or load grow high enough, a simple two−tier application will no longer handle your
demands. To help alleviate this problem, a range of different technologies have been introduced over the years
to allow you to abstract the raw data sources into collections of business logic. These collections can be used
in many different forms to present a range of applications to the end user.
Part VI: Building Big Systems
Moving up to the really huge systems that you might see in a site like Amazon.com demands even more of
your application. The skills and knowledge needed to implement these solutions is often very specialized.
How often will you get a complete system failure today? Most likely never, so you have to know how to build
applications that can deal with partial failures and still continue to operate normally. This part is devoted to
the Java technologies needed to deal with such applications.
Appendixes
While code and examples are extremely useful, there are many other pieces of information that you need to
know. The appendices cover Sun's Reference Implementation of the J2EE specification, listings of products
and vendors of J2EE systems, and also a glossary of terms to help you through all those acronyms.
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Part I: Getting Started
Chapter List
Chapter 1: Defining the Enterprise
Chapter 2: Introducing Enterprise Applications
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