Effective XML 50 Specific Ways to Improve Your XML

by Harold, Elliotte Rusty

• ISBN13: 9780321150400
• ISBN10: 0321150406
• Edition: 1st
• Format: Paperback
• Copyright: 2003-09-22
• Publisher: Addison-Wesley Professional

Summary

Praise for Effective XML "This is an excellent collection of XML best practices: essential reading for any developer using XML. This book will help you avoid common pitfalls and ensure your XML applications remain practical and interoperable for as long as possible." -Edd Dumbill, Managing Editor, XML.com and Program Chair, XML Europe "A collection of useful advice about XML and related technologies. Well worth reading both before, during, and after XML application development." -Sean McGrath, CTO, Propylon "A book on many best practices for XML that we have been eagerly waiting for." -Akmal B. Chaudhri, Editor, IBM developerWorks "The fifty easy-to-read items cover many aspects of XML, ranging from how to use markup effectively to what schema language is best for what task. Sometimes controversial, but always relevant, Elliotte Rusty Harold's book provides best practices for working with XML that every user and implementer of XML should be aware of." -Michael Rys, Ph.D., Program Manager, SQL Server XML Technologies, Microsoft Corporation "Effective XML is an excellent book with perfect timing. Finally, an XML book everyone needs to read! Effective XML is a fount of XML best practices and solid advice. Whether you read Effective XML cover to cover or randomly one section at a time, its clear writing and insightful recommendations enlighten, entertain, educate, and ultimately improve the effectiveness of even the most expert XML developer. I'll tell you what I tell all my coworkers and customers: You need this book." -Michael Brundage, Technical Lead, XML Query Processing, Microsoft WebData XML Team "This book provides great insight for all developers who write XML software, regardless of whether the software is a trivial application-specific XML processor or a fullblown W3C XML Schema Language validator. Mr. Harold covers everything from a very important high-level terminology discussion to details about parsed XML nodes. The well-researched comparisons of currently available XML-related software products, as well as the key criteria for selecting between XML technologies, exemplify the thoroughness of this book." -Cliff Binstock, Author, The XML Schema Complete Reference If you want to become a more effective XML developer, you need this book. You will learn which tools to use when in order to write legible, extensible, maintainable and robust XML code. Page 36: How do you write DTDs that are independent of namespace prefixes? Page 82: What do parsers reliably report and what don't they? Page 130: Which schema language is the right one for your job? Page 178: Which API should you choose for maximum speed and minimum size? Page 257: What can you do to ensure fast, reliable access to DTDs and schemas without making your document less portable? Page 283: Is XML too verbose for your application?Elliotte Rusty Harold provides you with 50 practical rules of thumb based on real-world examples and best practices. His engaging writing style is easy to understand and illustrates how you can save development time while improving your XML code. Learn to write XML that is easy to edit, simple to process, and is fully interoperable with other applications and code. Understand how to design and document XML vocabularies so they are both descriptive and extensib

Author Biography

Elliotte Rusty Harold is an adjunct professor of computer science at Polytechnic University in Brooklyn, New York, where he lectures on object-oriented programming and XML. His Cafe con Leche Web site has become one of the most popular sites for information on XML. He is the author of several well-respected books, including Processing XML with Java (Addison-Wesley, 2003), XML in a Nutshell, Second Edition (O'Reilly, 2002), and XML Bible, Second Edition (Wiley, 2001).

Table of Contents

Preface	p. xi
Acknowledgments	p. xiii
Introduction	p. XV
Element versus Tag	p. xvi
Attribute versus Attribute Value	p. xvii
Entity versus Entity Reference	p. xvii
Entity Reference versus Character Reference	p. xviii
Children versus Child Elements versus Content	p. xix
Text versus Character Data versus Markup	p. xxi
Namespace versus Namespace Name versus Namespace URI	p. xxii
XML Document versus XML File	p. xxii
XML Application versus XML Software	p. xxiii
Well-Formed versus Valid	p. xxiii
DTD versus DOCTYPE	p. xxiv
XML Declaration versus Processing Instruction	p. xxv
Character Set versus Character Encoding	p. xxvi
URI versus URI Reference versus IRI	p. xxvii
Schemas versus the W3C XML Schema Language	p. xxvii
Syntax	p. 1
Include an XML Declaration	p. 1
The version Info	p. 2
The encoding Declaration	p. 2
The standalone Declaration	p. 3
Mark Up with ASCII if Possible	p. 5
Stay with XML 1.0	p. 10
New Characters in XML Names	p. 11
C0 Control Characters	p. 13
C1 Control Characters	p. 15
NEL Used as a Line Break	p. 16
Unicode Normalization	p. 17
Undeclaring Namespace Prefixes	p. 18
Use Standard Entity References	p. 19
Comment DTDs Liberally	p. 21
The Header Comment	p. 23
Declarations	p. 26
Name Elements with Camel Case	p. 29
Parameterize DTDs	p. 32
Parameterizing Attributes	p. 35
Parameterizing Namespaces	p. 35
Full Parameterization	p. 37
Conditional Sections	p. 39
Modularize DTDs	p. 42
Distinguish Text from Markup	p. 51
White Space Matters	p. 52
The xml: space Attribute	p. 53
Ignorable White Space	p. 54
Tags and White Space	p. 54
White Space in Attributes	p. 55
Schemas	p. 57
Structure	p. 59
Make Structure Explicit through Markup	p. 59
Tag Each Unit of Information	p. 60
Avoid Implicit Structure	p. 63
Where to Stop?	p. 67
Store Metadata in Attributes	p. 69
Remember Mixed Content	p. 75
Allow All XML Syntax	p. 79
Build on Top of Structures, Not Syntax	p. 82
Empty-Element Tags	p. 86
CDATA Sections	p. 87
Character and Entity References	p. 90
Prefer URLs to Unparsed Entities and Notations	p. 91
Use Processing Instructions for Process-Specific Content	p. 95
Style Location	p. 96
Overlapping Markup	p. 98
Page Formatting	p. 101
Out-of-Line Markup	p. 102
Misuse of Processing Instructions	p. 103
Include All Information in the Instance Document	p. 104
Encode Binary Data Using Quoted Printable and/or Base64	p. 109
Quoted Printable	p. 109
Base64	p. 111
Use Namespaces for Modularity and Extensibility	p. 112
Choosing a Namespace URI	p. 113
Validation and Namespaces	p. 116
Rely on Namespace URIs, Not Prefixes	p. 117
Don't Use Namespace Prefixes in Element Content and Attribute Values	p. 121
Reuse XHTML for Generic Narrative Content	p. 124
Choose the Right Schema Language for the Job	p. 130
The W3C XML Schema Language	p. 130
Document Type Definitions	p. 131
RELAX NG	p. 133
Schematron	p. 134
Java, C#, Python, and Perl	p. 135
Layering Schemas	p. 138
Pretend There's No Such Thing as the PSVI	p. 139
Version Documents, Schemas, and Stylesheets	p. 143
Mark Up According to Meaning	p. 149
Semantics	p. 155
Use Only What You Need	p. 155
Always Use a Parser	p. 162
Layer Functionality	p. 166
Program to Standard APIs	p. 170
SAX	p. 171
DOM	p. 175
JDOM	p. 178
Choose SAX for Computer Efficiency	p. 178
Choose DOM for Standards Support	p. 183
Read the Complete DTD	p. 186
Navigate with XPath	p. 192
Serialize XML with XML	p. 201
Validate Inside Your Program with Schemas	p. 203
Xerces-J	p. 206
DOM Level 3 Validation	p. 210
Implementation	p. 213
Write in Unicode	p. 213
Choosing an Encoding	p. 214
A char Is Not a Character	p. 218
Normalization Forms	p. 219
Sorting	p. 221
Parameterize XSLT Stylesheets	p. 221
Avoid Vendor Lock-In	p. 226
Hang On to Your Relational Database	p. 230
Document Namespaces with RDDL	p. 233
Natures	p. 237
Purposes	p. 239
Preprocess XSLT on the Server Side	p. 241
Servlet-Based Solutions	p. 242
Apache	p. 244
IIS	p. 245
Serve XML+CSS to the Client	p. 246
Pick the Correct MIME Media Type	p. 249
Tidy Up Your HTML	p. 253
MIME Type	p. 254
HTML Tidy	p. 254
Older Browsers	p. 255
Catalog Common Resources	p. 257
Catalog Syntax	p. 258
Using Catalog Files	p. 259
Verify Documents with XML Digital Signatures	p. 263
Digital Signature Syntax	p. 264
Digital Signature Tools	p. 273
Hide Confidential Data with XML Encryption	p. 275
Encryption Syntax	p. 276
Encryption Tools	p. 282
Compress if Space Is a Problem	p. 283
Recommended Reading	p. 287
Index	p. 289
Table of Contents provided by Ingram. All Rights Reserved.

Excerpts

Learning the fundamentals of XML might take a programmer a week. Learning how to use XML effectively might take a lifetime. While many books have been written that teach developers how to use the basic syntax of XML, this is the first one that really focuses on how to use XML well. This book is not a tutorial. It is not going to teach you what a tag is or how to write a DTD. I assume you know these things. Instead it's going to tell you when, why, where, and how to use such tools effectively (and perhaps equally importantly when not to use them). This book derives directly from my own experiences teaching and writing about XML. Over the last five years. I've written several books and taught numerous introductory courses about XML syntax, APIs, and tools. Increasingly I'm finding that audiences are already familiar with the basics of XML. They know what a tag is, how to validate a document against a DTD, and how to transform a document with an XSLT style sheet. The question of what XML is and why to use it has been sufficiently well evangelized. The essential syntax and rules are reasonably well understood. However, although most developers know what a CDATA section is, they are not sure what to use one for. Although programmers know how to add attribute and child nodes to elements, they are not certain which one to use when.Since XML has become a fundamental underpinning of new software systems, it becomes important to begin asking new questions, not just what XML is, but how does one use it effectively? Which techniques work and which don't? Perhaps most importantly, which techniques appear to work at first but fail to scale as systems are further developed? When I teach programming at my university, one of the first things I tell my students is that it is not enough to write programs that compile and produce the expected results. It is as important (perhaps more important) to write code that is extensible, legible, and maintainable. XML can be used to produce robust, extensible, maintainable, comprehensible systems or it can be used to create masses of unmaintainable, illegible, fragile, closed code. In the immortal words of Eric Clapton, "It's in the way that you use it." XML is not a programming language. It is a markup language; but it is being successfully used by many programmers. There have been markup languages before, but in the developer community XML is far and away the most successful. However, the newness and unfamiliarity of markup languages have meant that many developers are using it less effectively than they could. Many programmers are hacking together systems that work, but are not as robust, extensible, or portable as XML promises. This is to be expected. Programmers working with XML are pioneers exploring new territory, opening up new vistas in software, and accomplishing things that could not easily be accomplished just a few years ago. However one definition of a pioneer is someone with an arrow in their back, and more than a few XML pioneers have returned from the frontier with arrows in their backs.Five years after the initial release of XML into the world, certain patterns and antipatterns for the proper design of XML applications are becoming apparent. All of us in the XML community have made mistakes while exploring this new territory, the author of this book prominently among them. However, we've learned from those mistakes, and we're beginning to develop some principles that may help those who follow in our footsteps to avoid making the same mistakes we did. It is time to put up some caution signs in the road. We may not exactly say "Here there be dragons", but we can at least say, "That road is a lot rockier than it looks at first glance, and you might really want to take this slightly less obvious but much smoother path off to the left."This book is divided into four parts beginning with the lowest layer of XML and gradually working up to the highest: Part I