A Basic Algebra of Stateless Connectors

The conceptual separation between computation and coordination in distributed computing systems motivates the use of peculiar entities commonly called connectors, whose task is managing the interaction among distributed components. Different kinds of connectors exist in the literature at different levels of abstraction. We focus on an algebra of connectors that exploits five kinds of basic connectors (plus their duals), namely symmetry, synchronization, mutual exclusion, hiding and inaction. Basic connectors can be composed in series and in parallel. We first define the operational, observational and denotational semantics of connectors, then we show that the observational and denotational semantics coincide and finally we give a complete normal-form axiomatization. The expressiveness of the framework is witnessed by the ability to model all the (stateless) connectors of the architectural design language CommUnity and of the coordination language Reo.