Checking Complex Compositions of Web Services Against Policy Constraints

Research in web services has allowed reusable, distributed, loosely coupled components which can easily be composed to build systems or to produce more complex services. Composition of these components is generally done in an ad-hoc manner. As compositions of services become more widely used and, inevitably, more complex, there is a need to ensure that compositions of services obey constraints. In this paper, we consider the need to provide policy constraints on service compositions, that define how services can be composed in a particular business setting. We describe compositions using WS-CDL and we use xlinkit to express policy constraints as consistency rules over XML documents.