XML Schema: The W3C's Object-Oriented Descriptions for XML

by Eric van der Vlist

Overview

If you need to create or use formal descriptions of XML vocabularies, the W3C's XML Schema offers a powerful set of tools for defining acceptable document structures and content. An alternative to DTDs as the way to describe and validate data in an XML environment, XML Schema enables developers to create precise descriptions with a richer set of datatypes?such as booleans, numbers, currencies, dates and times?that are essential for today's applications.Schemas are powerful, but that power comes with substantial complexity. This concise book explains the ins and outs of XML Schema, including design choices, best practices, and limitations. Particularly valuable are discussions of how the type structures fit with existing database and object-oriented program contexts. With XML Schema, you can define acceptable content models and annotate those models with additional type information, making them more readily bound to programs and objects. Schemas combine the easy interchange of text-based XML with the more stringent requirements of data exchange, and make it easier to validate documents based on namespaces.You'll find plenty of examples in this book that demonstrate the details necessary for precise vocabulary definitions. Topics include:

• Foundations of XML Schema syntax
• Flat, "russian-doll", and other schema approaches
• Working with simple and complex types in a variety of contexts
• The built-in datatypes provided by XML Schema
• Using facets to extend datatypes, including regular expression-based patterns
• Using keys and uniqueness rules to limit how and where information may appear
• Creating extensible schemas and managing extensibility
• Documenting schemas and extending XML Schema capabilities through annotations

In addition to the explanatory content, XML Schemaprovides a complete reference to all parts of both the XML Schema Structures and XML Schema Datatypes specifications, as well as a glossary. Appendices explore the relationships between XML Schema and other tools for describing document structures, including DTDs, RELAX NG, and Schematron, as well as work in progress at the W3C to more tightly integrate XML Schema with existing specifications.No matter how you intend to use XML Schema - for data structures or document structures, for standalone documents or part of SOAP transactions, for documentation, validation, or data binding ? all the foundations you need are outlined in XML Schema.

Product Details

ISBN-13:	9781449315375
Publisher:	O'Reilly Media, Incorporated
Publication date:	06/25/2002
Sold by:	Barnes & Noble
Format:	eBook
Pages:	400
File size:	3 MB

About the Author

Eric van der Vlist is the resident expert on XML schema languages on XML.com. He is also a member of the ISO DSDL committee, where standardization work on RELAX NG and related specifications is in progress. Eric is also the author of O'Reilly's XML Schema.

Table of Contents

	Preface	ix
1.	Schema Uses and Development	1
	What Schemas Do for XML	1
	W3C XML Schema	4
2.	Our First Schema	6
	The Instance Document	6
	Our First Schema	7
	First Findings	13
3.	Giving Some Depth to Our First Schema	15
	Working From the Structure of the Instance Document	15
	New Lessons	17
4.	Using Predefined Simple Datatypes	21
	Lexical and Value Spaces	21
	Whitespace Processing	23
	String Datatypes	24
	Numeric Datatypes	30
	Date and Time Datatypes	34
	List Types	41
	What About anySimpleType?	41
	Back to Our Library	41
5.	Creating Simple Datatypes	44
	Derivation By Restriction	45
	Derivation By List	59
	Derivation By Union	61
	Some Oddities of Simple Types	63
	Back to Our Library	65
6.	Using Regular Expressions to Specify Simple Datatypes	69
	The Swiss Army Knife	69
	The Simplest Possible Patterns	70
	Quantifying	71
	More Atoms	72
	Common Patterns	79
	Back to Our Library	83
7.	Creating Complex Datatypes	86
	Simple Versus Complex Types	86
	Examining the Landscape	87
	Simple Content Models	88
	Complex Content Models	91
	Mixed Content Models	115
	Empty Content Models	119
	Back to Our Library	121
	Derivation or Groups	126
8.	Creating Building Blocks	127
	Schema Inclusion	127
	Schema Inclusion with Redefinition	129
	Other Alternatives	135
	Simplifying the Library	137
9.	Defining Uniqueness, Keys, and Key References	141
	xs:ID and xs:IDREF	141
	XPath-Based Identity Checks	142
	ID/IDREF Versus xs:key/xs:keyref	149
	Using xs:key and xs:unique As Co-occurrence Constraints	151
10.	Controlling Namespaces	153
	Namespaces Present Two Challenges to Schema Languages	153
	Namespace Declarations	156
	To Qualify Or Not to Qualify?	158
	Disruptive Attributes	164
	Namespaces and XPath Expressions	165
	Referencing Other Namespaces	166
	Schemas for XML, XML Base and XLink	169
	Namespace Behavior of Imported Components	175
	Importing Schemas with No Namespaces	177
	Chameleon Design	179
	Allowing Any Elements or Attributes from a Particular Namespace	181
11.	Referencing Schemas and Schema Datatypes in XML Documents	184
	Associating Schemas with Instance Documents	184
	Defining Element Types	189
	Defining Nil (Null) Values	194
	Beware the Intrusive Nature of These Features...	195
12.	Creating More Building Blocks Using Object-Oriented Features	197
	Substitution Groups	197
	Controlling Derivations	205
13.	Creating Extensible Schemas	213
	Extensible Schemas	213
	The Need for Open Schemas	222
14.	Documenting Schemas	224
	Style Matters	224
	The W3C XML Schema Annotation Element	226
	Foreign Attributes	231
	XML 1.0 Comments	232
	Which One and What For?	233
15.	Elements Reference Guide	235
16.	Datatype Reference Guide	305
A.	XML Schema Languages	337
B.	Work in Progress	355
	Glossary	361
	Index	369