Delta-X is a code-generation environment for element management that includes an integrity-constraint maintenance system for XML integrity constraints. The system uses an integrity-constraint language based on Xpath,: a variant of the integrity-constraint model used in XML-schema.
The Delta-X toolset includes a type-checker for validating the sanity of a constraint against a DTD, and a code-generator that outputs incremental checking code. There is also a tool that infers integrity constraints from an XML document describing a data model.
This work is in collaboration with Glenn Bruns . Delta-X is used in many of Lucent's element management products. Those within the Lucent firewall can get more info at the Internal Delta-X site