Trace-based Verification of Rule-based Service Choreographies

The service choreography approach has been proposed for describing the global ordering constraints on the observable message exchanges between participant services in service oriented architectures. Recent work advocates the use of structured natural language, in the form of Semantics of Business Vocabulary and Rules (SBVR), for specifying and validating choreographies. This paper addresses the verification of choreographies - whether the local behaviours of the individual participants conform to the global protocol prescribed by the choreography. We describe how declarative specifications of service choreographies can be verified using a trace-based model, namely an adaptation of Shields' vector languages. We also use the so-called blackboard rules, which draw upon the Bach coordination language, as a middleware that adds reactiveness to this declarative setting. Vector languages are to trace languages what matrices are to linear transformations; they afford a more concrete representation which has advantages when it comes to computation or manipulation.