Towards Contract-based Testing of Web Services

Web Services are composed by linking together service providers and requestors. To ensure interoperability, the requestor's requirements for a service have to be matched against a service description offered by the provider. Besides data types and operation signatures, this requires service specifications to include behavioral information, like contracts specifying pre-and post-conditions of (required or provided) operations. In this paper, we propose to visualize contracts by graph transformation rules which blend well with a UML-based notion of data models and signatures. The operational interpretation of rules could turn out to be useful for simulating the behavior of required components in unit testing.