A.: Automata for context-dependent connectors

Abstract. Recent approaches to component-based software engineer-ing employ coordinating connectors to compose components into soft-ware systems. For maximum flexibility and reuse, such connectors can themselves be composed, resulting in an expressive calculus of connec-tors whose semantics encompasses complex combinations of synchroni-sation, mutual exclusion, non-deterministic choice and state-dependent behaviour. A more expressive notion of connector includes also context-dependent behaviour, namely, whenever the choices the connector can take change non-monotonically as the context, given by the pending ac-tivity on its ports, changes. Context dependency can express notions of priority and inhibition. Capturing context-dependent behaviour in for-mal models is non-trivial, as it is unclear how to propagate context in-formation through composition. In this paper we present an intuitive automata-based formal model of context-dependent connectors, and ar-gue that it is superior to previous attempts at such a model for the coordination language Reo.