ComposingWeb Services with Nondeterministic Behavior

The promise of Web services is to enable the composition of new distributed applications/solutions: when no available service can satisfy a client request, (parts of) available services can be composed and orchestrated in order to satisfy such a request. Service composition involves two different issues: the synthesis, in order to synthesize, either manually or automatically, a specification of how coordinating the component services to fulfill the client request, and the orchestration, i.e., how executing the previous obtained specification by suitably supervising and monitoring both the control flow and the data flow among the involved services. In this work, we address the automatic composition synthesis when the behavior of the available services is non-deterministic, and hence is not fully controllable by the orchestrator. The service behavior is modeled by the possible conversations the service can have with its clients. The presence of nondeterministic conversations stems naturally when modeling services in which the result of each interaction with its client on the state of the service can not be foreseen