An Approach to Checking the Compatibility for Web Services Specification Based on the Typed Graph Category

Web services represent a challenge and an opportunity for partiers wishing to expose product and services offerings through the Internet. Because Web services are dynamic collaborations generally, one of their key problems is to how automatically match the interface specifications between requestors and provider, it is necessary to formalize interface specifications. This paper proposes a formal notion of Web services modeling according to the graph category theory, and gives a method for transforming the visual interface specification which is represented by a semi-formal, UML-based class graph, into ML language representation, a language suitable for category. A concept of the structural and behavioral compatibility of the interface specifications is established, and an approach to constructing pullback and pushout, which are the weakest possible pre-condition and a stronger post-condition of an operation respectively, is provided.