Chapter 22.  XML Schema (XSDL) Tad Tougher Tutorial

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Chapter 22. XML Schema (XSDL)
Tad Tougher Tutorial

  • XML Schema definition language

  • Syntax and declarations

  • Simple and complex types

  • Locally-scoped elements

  • Schema inclusion

An XML DTD is a specific case of a more general concept called a schema definition. The dictionary defines schema as a "general conception of what is common to all members of a class." A schema definition takes that "conception" and turns it into something concrete that can be used directly by a computer.

There are many types of schema in use in the computer industry, chiefly for databases. DTDs are different in that the class for which they declare "what is common to all members" is a class of XML documents.

The popularity of XML has brought DTDs to entirely new constituencies. The database experts and programmers who are taking to XML in droves are examining it from the standpoint of their own areas of expertise and familiar paradigms.

All of these creative folks have ideas about what could be done differently. The World Wide Web Consortium has incorporated these ideas into a design for an enhanced schema definition facility called the XML Schema definition language (XSDL).

The name of the language is often shortened to "XML Schema", but we reserve that phrase for the name of the W3C spec. We call the language XSDL so you'll know when we are referring to the "schema definition language" as opposed to:

  • a particular "schema definition",

  • a conceptual "schema", or

  • the XML Schema specification.

The words "XML schema", unfortunately, could refer to any of those three things.

Caution

The XML Schema spec is several times longer than the XML specification itself. It is also quite intricate and formal. This chapter will informally teach a subset that is sufficiently functional for most projects and yet simple enough that we can teach it all in one chapter.




Amazon


XML in Office 2003. Information Sharing with Desktop XML
XML in Office 2003: Information Sharing with Desktop XML
ISBN: 013142193X
EAN: 2147483647
Year: 2003
Pages: 176

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