NOTE: These slides have not been updated since 2003. They have been superseded by the book An Introduction to XML and Web Technologies Addison-Wesley, and the accompanying online material. Please see http://www.brics.dk/ixwt/ for more information. Anders Møller and Michael Schwartzbach, February 2006

THE XML REVOLUTION  -  TECHNOLOGIES FOR THE FUTURE WEB

Rules

Example:

<if><element name="r:preparation"/> <declare><contents> <repeat><element name="r:step"/></repeat> </contents></declare> </if>

Rules can be:

• if rules, conditional rules guarded by boolean expressions over element properties (permitting context sensitive constraints!)
• declare rules, declaring which attributes and contents an element may have
• require rules, containing boolean expressions over element properties that are required to hold

Rules can be defined (given an ID for reference) to support modularity, as e.g. ANYCONTENT in the full example.

A document is validated through a top-down process, checking each element in turn. For each element,

• all its attributes and contents must be declared by some applicable declare rule
• all applicable additional requirements (require rules) must be satisfied

COPYRIGHT © 2000-2003 ANDERS MØLLER & MICHAEL I. SCHWARTZBACH