A Formal Approach to Service Specification and Matching based on Graph Transformation

When Web services are composed by linking service providers and requestors, the requestor’s requirements for a ”useful” service have to be matched against the service description offered by the provider. Among other things, service specifications (requirements or descriptions) may contain operation contracts specifying pre-conditions and effects of (required or provided) operations. In this paper we provide a semi-formal, UML-based notation for contracts and contract matching, as well as a formalization of these notions in terms of graph transformation. We establish the desired semantic relation between requestor and provider specifications and prove the soundness of our syntactic notion of matching w.r.t. this relation.