Practical DWR 2 Projects (Expert's Voice in Java)

570 Pages·2008·9.28 MB·English

by  Frank Zammetti

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EMPOWERING PRODUCTIVITY FOR THE JAVA™ DEVELOPER THE EXPERT’s VOICE® IN JAVA™ TECHNOLOGY
Companion
Author of eBook Available
Practical DWR 2 Projects
Practical Ajax Projects with
Java™ Technology
Practical
Practical JavaScript™, Dear Reader,
DOM Scripting, and Ajax Practical
Projects Ajax represents a brave, newish world of web development where coding on D
the client is just as important as on the server side. Hundreds of libraries exist
that purport to make it easier for you, and there’s always the “Do It Yourself”
approach. Which route should you take?
If you work with Java™ technologies, one choice that stands out is DWR, W DWR 2
or Direct Web Remoting. With DWR, JavaScript™-based client code that calls
server-side objects works as if it were all running in the same process space.
The simplicity and power DWR blends together has few rivals today.
In this, the first DWR book to be published, you’ll be introduced to DWR
R
and all it has to offer, including reverse Ajax, XML and annotation-based con-
figuration, container-managed security, simple POJO-based development, and
greatly simplified client-side coding. You’ll learn by doing as you explore six
fully functional applications including the following:
• A webmail client for remotely accessing your e-mail accounts 2
• A wiki for collaborative efforts
• A file manager for remotely managing your server’s file system
Projects
• A portal for enterprise reporting needs

• A project management/time-tracking system P
• Even a fun little game!
r
In addition to DWR, you’ll also see how other popular libraries help realize
o
the RIA/Web 2.0 vision, including Spring, Hibernate, dHTMLx, DataVision,
Freemarker, and Ext JS. j
e
If you’re doing RIA development in Java, DWR is for you, as too is this book!
c
Frank W. Zammetti
SCJP, MCSD, MCP, CNA, CIW Associate, author, husband, father, Vorlon t
s Explore the design and construction of six
complete, rich Web 2.0 applications utilizing DWR,
Companion eBook
one of the hottest libraries in the Ajax realm today.
THE APRESS JAVA™ ROADMAP
Pro Ajax and
Java™ Frameworks

See last page for details Foundations of Ajax Practical
on $10 eBook version DWR 2 Projects
Practical Ajax Projects
with Java™ Technology
SOURCE CODE ONLINE Z
a
www.apress.com ISBN-13: 978-1-59059-941-9 m Frank W. Zammetti
java.apress.com ISBN-10: 1-59059-941-1 m
54699 e
t Foreword by Joe Walker, Creator of DWR
t
US $46.99 i
Shelve in
Java Programming
User level:
9 781590 599419
Intermediate–Advanced
this print for content only—size & color not accurate spine = 1.072" 568 page count

9411FM.qxd 1/2/08 5:20 PM Page i
Practical DWR 2 Projects
Frank W. Zammetti
9411FM.qxd 1/2/08 5:20 PM Page ii
Practical DWR 2 Projects
Copyright © 2008 by Frank W.Zammetti
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-13 (pbk): 978-1-59059-941-9
ISBN-10 (pbk): 1-59059-941-1
ISBN-13 (electronic): 978-1-4302-0556-2
ISBN-10 (electronic): 1-4302-0556-3
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9411FM.qxd 1/2/08 5:20 PM Page iii
Let’s see ...this is my third book now ...the first I dedicated to my wife,kids,mom,dad,
and John Sheridan for keeping the Shadows off our backs.The second I dedicated to all
theanimals I’ve eaten,a batch of childhood friends who helped shape my early life,
DennyCrane,and my wife and kids once more.So,I’ve covered everyone that counts at
least once.So,who to dedicate this one to? Who’s worthy of my adulation and respect?
Oh,oh! I know ...ME! I dedicate this book to ME!
OK,fine,I guess I can’t do that.
So,I instead dedicate this book to my wife and kids.AGAIN.
I dedicate this book to my sister because I just realized I didn’tcover everyone
that counts,but now I have,sis!
I dedicate this book to the folks at Harmonix and Bungie because Guitar Hero,Rock Band,
and Halo just flat-out rule.I need some Dream Theater,Queensryche,Shadow Gallery,
Fates Warning,and Enchant to make my life complete though,so get on that,OK guys?
And lastly,I dedicate this book to all the alien species we have yet to meet.I just hope those
dudes need books on web programming,because my kids eat like you wouldn’t believe!
I’lleven take Quatloos!
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Contents at a Glance
Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
About the Author. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
About the Technical Reviewer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
About the Illustrator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
PART 1 n n nSetting the Table
nCHAPTER 1 An Introduction to Ajax,RPC,and Modern RIAs . . . . . . . . . . . . . . . . . . 3
nCHAPTER 2 Getting to Know DWR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
nCHAPTER 3 Advanced DWR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
PART 2 n n nThe Projects
nCHAPTER 4 InstaMail:An Ajax-Based Webmail Client. . . . . . . . . . . . . . . . . . . . . . 129
nCHAPTER 5 Share Your Knowledge:DWiki,the DWR-Based Wiki. . . . . . . . . . . 189
nCHAPTER 6 Remotely Managing Your Files:DWR File Manager. . . . . . . . . . . . . 259
nCHAPTER 7 Enter the Enterprise:A DWR-Based Report Portal. . . . . . . . . . . . . . 329
nCHAPTER 8 DWR for Fun and Profit (a DWR Game!). . . . . . . . . . . . . . . . . . . . . . . . 419
nCHAPTER 9 Timekeeper:DWR Even Makes Project
Management Fun!. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457
nINDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
v
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Contents
Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
About the Author. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
About the Technical Reviewer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
About the Illustrator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
PART 1 n n nSetting the Table
nCHAPTER 1 An Introduction to Ajax, RPC, and Modern RIAs. . . . . . . . . . . 3
A Brief History of Web Development:The “Classic”Model. . . . . . . . . . . . . 3
Dawn of a Whole New World:The PC Era. . . . . . . . . . . . . . . . . . . . . . . 5
Yet Another Revolution:Enter the Web . . . . . . . . . . . . . . . . . . . . . . . . . 7
What’s So Wrong with the Classic Web?. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Enter Ajax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Why Is Ajax a Paradigm Shift? On the Road to RIAs. . . . . . . . . . . . . . . . . . 18
The Flip Side of the Coin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Let’s Get to the Good Stuff:Our First Ajax Code,the Manual Way. . . . . . 25
A Quick Postmortem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Hey,I Thought This Was Ajax?!?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Cutting IN the Middle Man:Ajax Libraries to Ease Our Pain. . . . . . . . . . . . 33
Alternatives to Ajax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Hmm,Are We Forgetting Something? What Could It Be?
Oh Yeah,DWR!. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
nCHAPTER 2 Getting to Know DWR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
First Things First:Why DWR at All? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
DWR:RPC on Steroids for the Web . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
DWR Architectural Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Getting Ready for the Fun:Your DWR Development Environment. . . . . . . 49
vii
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viii nCONTENTS
A Simple Webapp to Get Us Started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Getting the Lay of the Land:Directory Structure . . . . . . . . . . . . . . . . 52
From Code to Executable:Ant Build Script . . . . . . . . . . . . . . . . . . . . . 53
Application Configuration:web.xml . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
The Markup:index.jsp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
On the Server Side:MathServlet.java. . . . . . . . . . . . . . . . . . . . . . . . . . 56
The Workhorse:MathDelegate.java. . . . . . . . . . . . . . . . . . . . . . . . . . . 58
It’s Alive:Seeing It in Action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Adding DWR to the Mix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
The DWR Test/Debug Page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Configuring DWR Part 1:web.xml . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Configuring DWR Part 2:dwr.xml. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Built-in Creators and Converters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
The <init> Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
The <allow> Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
The <signatures> Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Interacting with DWR on the Client. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Basic Call Syntax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Call Metadata Object Approach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
A Word on Some Funky Syntax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Setting Beans on a Remote Object. . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Extended Data Passing to Callbacks . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Interacting with DWR on the Server. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
DWR Configuration and Other Concepts:The engine.js File . . . . . . . . . . . 90
Call Batching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
A Quick Look at util.js,the DWR Utility Package . . . . . . . . . . . . . . . . . . . . . 92
Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
nCHAPTER 3 Advanced DWR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Locking the Doors:Security in DWR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Deny by Default. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
J2EE Security and DWR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
When Perfection Is Elusive:Error Handling in DWR Applications . . . . . . 101
Handling Warnings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Handling Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Handling Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Edge Cases:Improper Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
The Mechanics of Handling Exceptional Situations. . . . . . . . . . . . . 105
Another Word on Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Help from Elsewhere:Accessing Other URLs. . . . . . . . . . . . . . . . . . . . . . . 107