Session Centered Calculi for Service Oriented Computing

Within the European project SENSORIA, we are developing formalisms for service description that lay the mathematical basis for analysing and experimenting with components interactions, for combining services and formalising crucial aspects of service level agreement. One of the outcome of this study is pSCC, a process calculus with explicit primitives for service definition and invocation. Central to pSCC are the notions of session and pipelining. Sessions are two sided and can be equipped with protocols executed by each side during an interaction and permit interaction patterns that are more structured than the simple one-way and request-response ones. Pipeline permits exchange of values between among sessions. The calculus is also equipped with operators for handling (unexpected) session closures that permit programming smooth propagation of session closures to partners and subsessions, so as to avoid states with dangling or orphan sessions. In the talk we will present SCC and discuss other alternatives that are (or have been) considered within the project.