A critical issue in the choreographed services development is the conciliation of interaction protocol mismatches that affect the cooperation among the services to be integrated in the composite service. This chapter attempts to answer such an issue by presenting a mediation framework that supports the development and management of choreographed services by offering a loosely-coupled integration model and a flexible management of protocol mismatches. Such features are obtained by introducing (i) an action-based representation of the functions offered by a Web service; (ii) an explicit management of the state of the choreographed service, which determines the operations to be carried out in order to contribute to the service completion; (iii) an event-driven Web service execution model, which makes it possible to abandon the direct invocation of Web service operations in favour of an autonomous execution of actions, based on the available context information.
FACETA*: Checkpointing for Transactional Composite Web Service Execution based on Petri-Nets
