Structured Global Programming for Communication Behaviour

This paper presents two different paradigms of description of communication behaviour, one focussing on global message flows and another on endpoint behaviours, as formal calculi based on session types. The global calculus originates from Choreography Description Language, a web service description language developed by W3C WS-CDL working group. The end-point calculus is a typed π-calculus. The global calculus describes an interaction scenario from a vantage viewpoint; the endpoint calculus precisely identifies a local behaviour of each participant. After introducing the static and dynamic semantics of these two calculi, we explore a theory of endpoint projection which defines three principles for well-structured global description. The theory then defines a translation under the three principles which is sound and complete in the sense that all and only behaviours specified in the global description are realised as communications among end-point processes. Throughout the theory, underlying type structures play a fundamental role.