In the Service Oriented Architecture (SOA) model, a service is characterized by its exchange of asynchronous messages, and a service contract is a desirable composition of a variety of messages. Though this model is simple, implementing large-scale, cross-organizational distributed applications may be difficult to achieve in general, as there is no guarantee that service composition will be possible because of incompatibilities of Web service contracts. We categorize compatibility issues in Web service contracts into two broad categories: (a) between contracts of different services (which we define as a composability problem), and (b) a service contract and its implementation (which we define as a conformance problem). This chapter examines and addresses these problems, first by identifying and specifying contract compatibility conditions, and second, through the use of compatibility checking tools that enable application developers to perform checks at design time.
Evaluation of a Semi-automated Semantic Annotation Approach for Bootstrapping the Analysis of Large-Scale Web Service Networks