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01 549863 FM.qxd 1/28/04 9:43 AM Page iii XML 1.1 Bible 3rd Edition Elliotte Rusty Harold 01 549863 FM.qxd 1/28/04 9:43 AM Page ii 01 549863 FM.qxd 1/28/04 9:43 AM Page i XML 1.1 Bible 3rd Edition 01 549863 FM.qxd 1/28/04 9:43 AM Page ii 01 549863 FM.qxd 1/28/04 9:43 AM Page iii XML 1.1 Bible 3rd Edition Elliotte Rusty Harold 549863 FM.qxd 2/3/04 10:41 PM Page iv XML 1.1 Bible, 3rd Edition Published by Wiley Publishing, Inc. 10475 Crosspoint Boulevard Indianapolis, IN 46256 www.wiley.com Copyright 2004 by Wiley Publishing, Inc., Indianapolis, Indiana Published simultaneously in Canada ISBN: 0-7645-4986-3 Manufactured in the United States of America 10 9 8 7 6 5 4 3 2 1 3O/RT/QS/QU/IN No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. Requests to the Publisher for permission should be addressed to the Legal Department, Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256, (317) 572-3447, fax (317) 572-4447, E-Mail: [email protected]. LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY:THE PUBLISHER AND THE AUTHOR MAKE NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT LIMITATION WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE. NO WARRANTY MAY BE CREATED OR EXTENDED BY SALES OR PROMOTIONAL MATERIALS. THE ADVICE AND STRATEGIES CONTAINED HEREIN MAY NOT BE SUITABLE FOR EVERY SITUATION. THIS WORK IS SOLD WITH THE UNDERSTANDING THAT THE PUBLISHER IS NOT ENGAGED IN RENDERING LEGAL, ACCOUNTING, OR OTHER PROFESSIONAL SERVICES. IF PROFESSIONAL ASSISTANCE IS REQUIRED, THE SERVICES OF A COMPETENT PROFESSIONAL PERSON SHOULD BE SOUGHT. NEITHER THE PUBLISHER NOR THE AUTHOR SHALL BE LIABLE FOR DAMAGES ARISING HEREFROM. THE FACT THAT AN ORGANIZATION OR WEBSITE IS REFERRED TO IN THIS WORK AS A CITATION AND/OR A POTENTIAL SOURCE OF FURTHER INFORMATION DOES NOT MEAN THAT THE AUTHOR OR THE PUBLISHER ENDORSES THE INFORMATION THE ORGANIZATION OR WEBSITE MAY PROVIDE OR RECOMMENDATIONS IT MAY MAKE. FURTHER, READERS SHOULD BE AWARE THAT INTERNET WEBSITES LISTED IN THIS WORK MAY HAVE CHANGED OR DISAPPEARED BETWEEN WHEN THIS WORK WAS WRITTEN AND WHEN IT IS READ. For general information on our other products and services or to obtain technical support, please contact our Customer Care Department within the U.S. at (800) 762-2974, outside the U.S. at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Library of Congress Control Number: 2004101453 Trademarks:Wiley and and the Wiley Publishing logo are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and other countries, and may not be used without written permission. All other trademarks are the property of their respective owners. Wiley Publishing, Inc., is not associated with any product or vendor mentioned in this book. 01 549863 FM.qxd 1/28/04 9:43 AM Page v About the Author Elliotte Rusty Harold is an internationally respected writer, programmer, and educator, both on the Internet and off. He got his start writing FAQ lists for the Macintosh newsgroups on Usenet and has since branched out into books, Web sites, and newsletters. He’s an adjunct professor of computer science at Polytechnic University in Brooklyn, New York. His Cafe con Leche Web site at http://www.cafeconleche.org/has become one of the most popular indepen- dent XML sites on the Internet. Elliotte is originally from New Orleans, to which he returns periodically in search of a decent bowl of gumbo. However, he currently resides in the Prospect Heights neighborhood of Brooklyn with his wife Beth, and his cats Charm (named after the quark) and Marjorie (named after his mother-in-law). When not writing books, he enjoys working on genealogy, mathematics, free software, and quantum mechanics. His previous books include The Java Developer’s Resource,Java Network Programming,Java Secrets,JavaBeans,Java I/O, XML: Extensible Markup Language, XML in a Nutshell, Processing XML with Java, and Effective XML. 01 549863 FM.qxd 1/28/04 9:43 AM Page vi Credits Acquisitions Editor Executive Editorial Director Jim Minatel Mary Bednarek Development Editor Project Coordinator Marcia Ellett Erin Smith Technical Editor Graphics and Production Specialists David Schultz Joyce Haughey Jennifer Heleine Production Editor KristinMcMullan Angela Smith Heather Ryan Mary Gillot Virgin Copy Editor Joanne Slike Quality Control Technicians Laura Albert Editorial Manager Susan Moritz Mary Beth Wakefield Carl William Pierce Vice President & Executive Group Permissions Editor Publisher Laura Moss Richard Swadley Media Development Specialist Vice President and Executive Greg Stafford Publisher Robert Ipsen Proofreading and Indexing TECHBOOKS Production Services Vice President and Publisher Joseph B. Wikert 01 549863 FM.qxd 1/28/04 9:43 AM Page vii Preface W elcome to the third edition of the XML 1.1 Bible. When the first edition was published about five years ago, XML was a promising technology with a small but growing niche. In the last half decade, it has absolutely exploded. XML no longer needs to be justified as a good idea. In fact, the question developers are ask- ing has changed from “Why XML?” to “Why not XML?” XML has become the data format of choice for fields as diverse as stock trading and graphic design. More new programs today are using XML than aren’t. A solid understanding of just what XML is and how to use it has become a sine qua nonfor the computer literate. The XML 1.1 Bible,3rd Edition is your introduction to the exciting and fast-growing world of XML. With this book, you’ll learn how to write documents in XML and how to use style sheets to convert those documents into HTML so that legacy browsers can read them. You’ll also learn how to use document type definitions (DTDs) and schemas to describe and validate documents. You’ll encounter a variety of XML applications in many domains, ranging from finance to vector graphics to genealogy. And you’ll learn how to take advantage of XML for your own unique projects, programs, and web pages. What’s New in the Third Edition The French philosopher and mathematician Blaise Pascal once wrote in a letter, “I have only made this longer because I have not had the time to make it shorter.” I know how he felt. The first edition of the XML Biblewas written under great time pressure, was finished well after deadline, and totaled more than 1000 pages, the largest book I had written up to that point. My favorite reader comment about that edition was, “It would seem to me that if you asked the author to write 10,000 words about the colour blue, he would be able to do it without breaking into a sweat.” While I probably could write 10,000 words about blue, for the third edition, I did try to restrain myself and take the time to write more concisely. I rewrote the book from the ground up; and while I retained the basic flavor and outline that proved so popular with the first edition, I tightened up the writing and cut many examples down to size. With the benefit of five years of hindsight, I have also been able to expand coverage of promising new technologies (schemas, XInclude, XHTML, SVG, XML Base, and RDDL) while eliminating coverage of applications that proved to be less useful than they initially appeared (WML, VML, CDF, HTML+TIME, RDF, and so on). The result is a more concise, approachable volume that covers more of what you need to know and less of what you don’t. If you liked the first or second edition, you’re going to like the third edition even more. I’m confident you’ll find this an even more useful tutorial and reference.