XML Base provides a means of associating XML elements with Uniform Resource Identifiers (URIs). Learn how to more precisely specify how relative URIs are resolved in relevant XML processing actions.

URIs and Internationalized Resource Identifiers (IRIs) are important in almost all XML applications. They are the glue for XML entities, including XInclude and other methods of document combination as well as many technologies that make reference to external resources. A URI can be specified relative to another URI, and usually if you specify a relative URI in an XML document, it is resolved relative to how the document was loaded by the processor. Sometimes the document author wants more control over how URIs are resolved, and XML Base [W3C Recommendation] offers such control. It allows you to associate an XML element with a base URI so that relative URIs within that element are resolved according to this overridden base rather than the URI of the document entity as a whole. For example, if an XML element contains a link that uses a relative URL, the absolute URL to be linked will be determined by referring to the base URI of the element, which might be specified on that element or on one of its ancestors.

Resources

• Dan Connolly gives a readable introduction to URIs, with a section on XML Base, in Untangle URIs, URLs, and URNs (developerWorks, June 2005).
  
  
• ZVON offers an XML Base tutorial.
  
  
• Chimezie Ogbuji and Uche Ogbuji's tutorial, Develop Python/XML with 4Suite, Part 4: Composition and updates, introduces XML Base as well as XPointer Framework, XInclude, and XUpdate (developerWorks, October 2002).
  
  
• Read about other XML standards: Index of XML standards.
  
  
• Participate in any of several XML-centered forums: XML zone discussion forums.
  
  
• Get involved in the developerWorks community: developerWorks blogs
  
  
• Find out how you can become an IBM-Certified Developer in XML and related technologies at IBM XML certification.
  
  
• See the developerWorks XML Zone for a wide range of technical articles and tips, tutorials, standards, and IBM Redbooks at XML technical library.
  
  
• Stay current with technology in these sessions: developerWorks technical events and webcasts.
  
  
• Build your next development project with trial software available for download directly from developerWorks: IBM trial software
  
  

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