Domain-independent, composable Web services policy assertions

The current model for the predicates, or "Assertions", used in a WS-Policy instance is for each policy domain to design new schema elements for that domain\´s Assertions. Their semantics are defined in an associated specification and are domain-specific. This model leads to interoperability and maintenance problems and hinders dynamic service composition. WS-Policy constraints is a domain-independent language for writing Assertions that is based on the Web Services Policy Language subset of XACML; it differs in addressing only the Assertion layer. This paper describes problems with domain-specific Assertions, the WS-Policy constraints alternative, and problems encountered in the development of this language