Monsell have released DeltaXML, a set of tools to help monitor and identify changes to XML files.

Essentially, the DeltaXML tools "Comparator" and "Combiner" are the equivalent of the Unix tools "diff" and "patch". Comparator allows you to produce a delta between one XML file and another, and Combiner allows the application of a delta to an XML file.

Tools are available to work with either DTDs or XML Schemas, producing intermediate schema definitions for the delta file, as well as a couple of specialist tools for NewsML and EXPRESS. Example output is available from the DeltaXML web site.

DeltaXML tools require Java 1.2 or better, and are commercially available, starting at US $99. For small sized files, no license is required.