 | Level: Intermediate Contributors: W3C 06 Feb 2007
Updated 25 Apr 2007 W3C XML Schema (WXS), a grammar-based XML schema language,
is used to define and limit XML vocabularies. It is the foundation of
some other standards in areas from XML messaging to data binding. Learn
about its relationship to other schema language technologies.
XML Schema Part 1:
Structures Second Edition
and
XML Schema Part 2: Datatypes
Second Edition
[W3C Recommendations] define another schema
language for XML. The first part allows you to constrain the structure
of the document, and the second part allows you to constrain the
contents of simple elements and attributes. WXS has faced criticism for
complexity and a lack of expressiveness; the result is competition from
other languages such as RELAX NG. Increasingly, people are just using
whatever schema language suits them best and turning to an impressive
crop of emerging tools to convert from one form to another according to
need. Many other specifications have used the WXS Datatypes
specification, although there have been calls to develop alternative
data type systems. The working group has started work on WXS 1.1 -- XML Schema 1.1 Part 1:
Structures and XML
Schema 1.1 Part 2: Datatypes [in development]. These look to fix
some of the much-reported problems with the 1.0 versions while retaining
maximum backward compatibility.
Work is also winding down on
Basic XML Schema Patterns
for Databinding Version 1.0
[in development], which provides
Schema usage advice for users of data binding systems. Data
binding is a method of converting XML instances into application objects
of a certain structure, and vice versa.
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