Analysis of Realizability Conditions for Web Service Choreographies

Web service choreography languages allow for the description of multipart collaborations from a global point of view, specifying the information exchanged by the participants in order to accomplish a common business goal. An important issue, emerging from the choreography modelling, is the protocol realizability, i.e., the possibility to extract the local specifications of the participants, so that their interactions preserve certain crucial properties of the global description. In this paper, we present a formal framework for the definition of both the global protocols and the local specifications. The key feature of the approach is that it allows for arbitrary communication models (synchronous/asynchronous, with/without buffers) in the composition of the local specifications. We introduce a hierarchy of realizability notions that allows for capturing various properties of the global specifications, and associate specific communication models to each of them. We also present an approach, based on the analysis of the communication models, that allows to associate a particular level of realizability to the global protocol specification.