Provides support for XML entity resolution through a XML catalog file.

The association between an XML instance document and its associated schemata is made through namespace references. An instance document can provide a 'hint' to the schema location for the parser but it is unlikely that any path contained in the schemaLocation attribute will be valid both for the sender and the receiver.

The best approach to locating the schema for a namespace is to look it up in a 'catalog' which holds either an explicit mapping or a set of rules for transforming the namespace URI. This keeps an hardcoded system paths out of the processing applications code base.

The original catalog format was created for SGML processing. A new standard proposed by OASIS is more focussed on XML document processing and is implemented by these classes.

A simple example of a catalog would be the following for the FpML schema.

<!DOCTYPE catalog
  PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
         "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd">
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"
         prefer="public">
  <public publicId="http://www.fpml.org/2003/FpML-4-0"
          uri="fpml-main-4-0.xsd"/>
</catalog>

Related Documentation

The OASIS specification for the XML catalog file can be found at: