What is an XML model?

About XML

Why use XML? The eXtensible Markup Language is used for different reasons:

♦It describes and structures data, whereas HTML only displays data

♦It uses a self-describing and personalized syntax

♦It can be exchanged between incompatible systems, since data is stored in plain text format

DTD, XSD or XDR The structure of an XML model is described by a DTD, an XSD or an XDR file:

♦A DTD file is a basic way to describe the structure of an XML document. It is a raw list of all the legal elements making up an XML document

Extract of a DTD file:

♦An XSD file (or schema) is an elaborated way to describe the structure of an XML document. It can support namespaces, derivations, keys, simple and complex user-defined data types and a robust collection of predefined data types

4

PowerDesigner

Page 16
Image 16
Sybase manual About XML