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 They have been superseded by the book An Introduction to XML and Web Technologies Addison-Wesley, and the accompanying online material.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

XML Base

• http://somewhere/somefile.xml is an absolute URI
• somefile.xml is a relative URI

Inspired by the <base href="..."> mechanism in HTML, XML Base provides a uniform way of resolving relative URIs.

In the following example:

<... xml:base="http://www.daimi.au.dk/">   <... href="~mis/mn/index.html" .../> </...>

the value of href attribute can be interpreted as the absolute URI http://www.daimi.au.dk/~mis/mn/index.html.

• the xml namespace prefix is hardwired by the Namespace specification
• xml:base has lexical scope (as namespace declarations)
• the URI used to access the document is used as default URI base

Examples of applications:

• XLink (requires XML Base support)
• XHTML (will use XML Base)
• Namespaces (does not conform to XML Base, but it ought to...)
• your future XML language

Future XML parsers will support Namespaces, XInclude, and XML Base.

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