The  OASIS CAM specification provides an XML-scripting system for validating B2B transaction structures and content (http://www.oasis-open.org/committees/cam).

The jCAM open source implementation (http://www.jcam.org.uk) provides a Java-based component for use with your ebXML messaging systems.  The focus is on delivering a quick and easy way for your partners to ensure that their business transactions comform to the correct business rules needed.