Joining the swelling ranks of tools for generating deltas between XML documents, VMTools is a new open source Java toolkit.

Features include:

• cost optimizer finds differences in document oriented XML as quickly as in data-oriented XML
• sample programs show "diff" and "patch" style functionality in a few dozen lines each
• web-based DifferenceGenerator and PatchApplicator available online
• builds on JDOM
• XPath subset implementation

VMTools is available for download under an Apache-like open source license.