XSLT and XPATH: A Guide to XML Transformations

794 Pages·2001·2.54 MB·English

by  John Robert Gardner

XSLT and XPATH: A Guide to XML Transformations
By John Robert Gardner, Zarella L. Rendon

Publisher : Prentice Hall PTR
Pub Date : July 01, 2001
ISBN : 0-13-040446-2

Pages : 588
Mastering XSLT and XPath gives you unprecedented control over your
information-and helps you leverage virtually every new XML technology,
from XLink to schemas. Discover XSLT's powerful vocabulary of
programming-like features and learn how to build custom solutions that
resist obsolesence. By the end of the first chapter,you'll be performing
XML-to-HTML conversions for display in any web browser. Then build on
your knowledge through a series of hands-on examples that transform you
into an XSLT/XPath expert!

Copyright
Preface
Why Should You Use XSLT?
Who Is This Book For?
Organization
Conventions
Versions

Acknowledgments
Readers and Contributors

Chapter 1. Anatomy of an XSLT Stylesheet
Section 1.1. What Is Markup?
Section 1.2. What Is XSLT?
Section 1.3. What Is XPath?
Section 1.4. XSLT Stylesheet Concepts
Section 1.5. Terminology for XSLT
Section 1.6. Climbing 'Round the Family Tree: Addressing in XSLT

Chapter 2. Fundamental Concepts of XSLT Stylesheets
Section 2.1. Boilerplates for XSLT Stylesheets
Section 2.2. Embedding Stylesheets in XML Documents
Section 2.3. XSLT Stylesheet Terminology
Section 2.4. XML Components of XSLT Stylesheets

Chapter 3. Advanced Stylesheet Concepts
Section 3.1. Templates: The Building Blocks of Transformations
Section 3.2. Built-in Template Rules

Chapter 4. XPath Expressions
Section 4.1. XPath Syntax and Terminology
Section 4.2. Abbreviations

Chapter 5. XPath Functions
Section 5.1. XPath Function Library
Section 5.2. The Node-set Core Function Group
Section 5.3. String Core Function Group
Section 5.4. Boolean Core Function Group
Section 5.5 . Number Core Function Group

Chapter 6. Building New XML Documents with XSLT
Section 6.1. Creating Elements with LREs
Section 6.2. The <xsl:element> Instruction Element
Section 6.3. Creating Attributes with the <xsl:attribute> Instruction Element
Section 6.4. The <xsl:attribute-set> Top-Level Element
Section 6.5. The <xsl:text> Instruction Element
Section 6.6. Adding Attributes to LREs
Section 6.7. Comments and Processing-Instructions
Section 6.8. Namespace Aliases

Chapter 7. Using Multiple Stylesheets
Section 7.1. Working with External Stylesheets
Section 7.2. Template Rule Processing and Priorities

Chapter 8. Working with Variables
Section 8.1. Declaring and Binding Variables
Section 8.2. Result Tree Fragments
Section 8.3. Using Variable References
Section 8.4. Comparing <xsl:variable> and <xsl:param>
Section 8.5. Comparing <xsl:with-param> to <xsl:param> and

<xsl:variable>

Chapter 9. Duplication, Iteration, and Conditional XSLT Elements
Section 9.1. The <xsl:copy-of> Instruction Element
Section 9.2. The <xsl:copy> Instruction Element
Section 9.3. The <xsl:for-each> Instruction Element
Section 9.4. The <xsl:sort> Element
Section 9.5. The <xsl:if> Instruction Element
Section 9.6. The <xsl:choose> Instruction Element
Section 9.7. The <xsl:number> Instruction Element

Chapter 10. Controlling Output Options
Section 10.1. The <xsl:output> Top-Level Element
Section 10.2. The <xsl:strip-space> and <xsl:preserve-space> Top-Level

Elements
Section 10.3. Generating Error Messages and Logs

Chapter 11. XSLT Functions and Related XSLT Elements
Section 11.1. XSLT Function Groups
Section 11.2. String XSLT Functions
Section 11.3. The Boolean XSLT Function Group

Chapter 12. XSLT Processors, Extensions, and Java
Section 12.1. XSLT Processors
Section 12.2. Extension Elements and Functions
Section 12.3. Namespaces
Section 12.4. Java
Section 12.5. Commercial XSLT Processors

Chapter 13. Xalan, Saxon, and XT
Section 13.1. Xalan
Section 13.2. Saxon
Section 13.3. XT
Section 13.4. Generating Multiple Output Files Using Saxon, Xalan, or XT

Appendix A. Case Studies
Section A.1. Lists
Section A.2. MARC Records: The ATLAS Project from ATLA-CERTR at Emory University
Section A.3. The Harvard-Kyoto Classics Project with Vedic Literature

Appendix B. Grouping Using the Muenchian Method
by Jeni Tennison

Appendix C. Using XSLT for the Artificial Intelligence "N-Queens" Problem
by Oren Ben-Kiki
Section C.1. Architecture
Section C.2. The Stylesheet
Section C.3. Final notes

Copyright
Library of Congress Cataloging-in-Publication Data
Gardner, James Robert.
XSLT and XPath: a guide to XML transformations / James Robert Gardner and Zarella
L. Rendon.
p. cm.
Includes index.
ISBN 0-13-040446-2
1. XML (Document markup language) 2. Internet programming. I. Rendon, Zarella L.
II. Title. III. Series.
QA76.76.H94 R46 2001
005.7'2—dc21 2001016422
© 2002 Prentice Hall PTR
Prentice-Hall, Inc.
Upper Saddle River, NJ 07458
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Dedication
For Dale
Preface
You've heard of XML; your manager wants you to use it in your applications. Now what?
You've used HTML, and you know what a tag is; you know that it is somehow related to
XML. You may even know what XML is and what it does. What you may not know is that,
while XML identifies and adds structure to the content of a document, it does not tell you
anything about how to process that content, or how to do anything useful with it beyond
storage. This is good news, because this means your content can be used for many
different purposes.
There are many things you can use to process content once it is marked up using XML.
However, we have chosen to talk about the only standard application that allows you to
do many different things with it. With XSLT, you can add style to XML, convert it to other
XML, or simply chop it up and regenerate it in a different form.
XSLT is the power behind the throne of XML. It assures that every level of every piece of
XML data is accessible and reusable across platforms and forward in time. It is not an
exaggeration to say that XSLT and its companion XPath are the very glue and mortar that
hold together and build the endlessly varying applications of markup data for any industry,
academy, or individual. XSLT is the fastest cure for the fear of having obsolescence in a
data or information architecture design.
XSLT is easy to use. In fact, XSLT itself is XML. XSLT "speaks the language," or the
syntax, of XML with a powerful vocabulary of programming-like features that are
nonetheless easy to use, learn, and understand.
XSLT attempts to be a bridge to nonprogrammers, bringing the easily understood syntax
of XML together with a powerful scripting mechanism and simple pathing approach to
document navigation.
It is our belief—and our approach in writing this book—that both the experienced
programmer and the newly trained markup technologist can become more comfortable
with the potent set of tools for preserving, augmenting, updating, and delivering XML
data—whether it's on the Web or your corporation's intranet or B2B.
If you are constantly wishing you had just a little more control over your information, this
book will deliver that—and much more. In fact, by the end of the first chapter, you will be
able to perform basic conversions from XML documents to HTML that will display in any
Web browser. Subsequent chapters build upon and enhance that base of knowledge,
matching examples with detailed explanations and providing focus upon commonly
misunderstood areas.
When you read this book, have your computer handy. Take the time to load up one of the
XSLT processors and work along as you read. Learning by doing is always best,
especially with XSLT and XPath. Chapter 13 will show you how to install the software
included on the CD. Each example in the book is found on the CD in the examples
directory, organized by chapter.
XSLT is rewarding and creative to use. Be prepared to enjoy this learning experience.
You will be surprised by how quickly productive use of this technology increases.
Why Should You Use XSLT?
Browsers display HTML, not general XML tags. You have to do something with the XML
once you have it. Can you print with XML? Can you send XML to the Web? Can you
browse XML? Yes, but not alone.
XSLT lets you convert XML to HTML, other types of XML or just plain text. With a little
creativity, and the proper knowledge of XSLT, you can generate practically any form of
output from XML.
XSLT provides quick, easy solutions to all XML transformation issues. However, the
designers of XSLT did not intend for you to use the specification without additional help.
"This book, along with the proper tools, is what is required for XML to succeed with the
average business application."
—Sharon Adler, Co-Chair W3C XSL Working Group
The latest version of XSLT (for which this book is written) is 1.0. There are many
additional features that are being considered by the W3C XSL committee, and version
2.0 promises to add some of these new features, as well as provide support for XML
Schema, XML Query, and others.
Who Is This Book For?
This book is for anyone who works with electronic data and wants to enable XML
transformations without a difficult programming language learning curve. If you are
comfortable working with SGML, XML, or even HTML, you will benefit greatly from the
common markup syntax.
Some people may find XSLT difficult because it is not a procedural programming
language. Most programming languages have a very structured, concise syntax. The
syntax of XSLT is XML and is designed to be human readable and easily understandable.
You must have some knowledge of markup before using XSLT.
Some people may find XSLT difficult to use because it does not provide solutions to every
transformation situation. For example, you cannot use XSLT to convert text to XML.
There are situations when additional processing may be required. However, for most of
your day-to-day XML transformations, XSLT is the tool of choice.
Organization
The book is organized to build a base of knowledge that will be added to chapter by
chapter. Basic XSLT concepts and a brief overview of XML are covered in Chapter 1. The
remainder of the chapters add functionality as required when creating stylesheets. The
more complex the problem, the later it is covered.
Chapter 1 provides everything you need to know about XML and XSLT in a nutshell. This
chapter gives a good overview with minimum syntax, and can be used by people at any
level of markup experience as a review or for general information.
Chapter 2 covers stylesheet concepts that are crucial to understanding XSLT, as well as
general stylesheet terminology.
Chapter 3 adds more concepts, a little more explanation and usage, and an in-depth
study of templates to the basics covered in Chapters 1 and 2.
Chapter 4 defines and explains XPath expressions and patterns.
Chapter 5 covers XPath functions, which are crucial to using most of the elements in
XSLT.
Chapter 6 walks through the creation of new XML elements and attributes using several
different methods.
Chapter 7 discusses the use of multiple stylesheets by including and importing them, as
well as a discussion on template priority.
Chapter 8 shows how to work with variables and parameters.
Chapter 9 covers anything that is in some way iterative or conditional, as well as the
utilities required to copy XML from the input to the output.
Chapter 10 details the options for controlling output types, as well as stripping and
preserving whitespace, and generating error messages.
Chapter 11 covers XSLT functions and their related elements, including importing
external XML documents with the document() function, and using keys with
<xsl:key>.
Chapter 12 discusses extensions, processors, and Java, as well as three "commercial"
XSLT processors.
Chapter 13 describes three "freeware" processors: Xalan, Saxon, and XT, along with
installation instructions and extension implementations.
There are three appendices that cover a variety of topics and case studies, as well as
contributed material.
Conventions
XML, XSLT, and HTML elements, when discussed in the text, are always found as
markup. For example <xsl:stylesheet> will always have the opening <and
closing>, and will be in courier font. Any expression or function, such as count(),
will also be in courier.
Each element has an element model definition, taken directly from the XSLT specification,
when provided, as shown below. The element model is organized as an XML element
with an optional category description (as a comment), followed by the start tag with any
available attributes, the content (as a comment), and a closing tag (unless the element is
empty). Attributes are bold if they are required, and their value is shown in italic if it has a
special defined content type, or in quotes if it has a literal value. Elements in the content
can be optional, designated with a ?, or optional and repeatable, designated with a *.
<!-- Category: instruction -->

<xsl:for-each

select = node-set-expression>

<!-- Content: (xsl:sort*, template) -->

</xsl:for-each>
Function prototypes are taken directly from the XPath and XSLT specifications, and are
formatted with the key word Function, followed by a colon, followed by an object return