Channel-based coordination via constraint satisfaction

Abstract

Coordination in R eo emerges from the composition of the behavioural constraints of primitives, such as channels, in a component connector. Understanding and implementing R eo , however, has been challenging due to the interaction of the channel metaphor, which is an inherently local notion, and the non-local nature of the constraints imposed by composition. In this paper, the channel metaphor takes a back seat. We focus on the behavioural constraints imposed by the composition of primitives and phrase the semantics of R eo as a constraint satisfaction problem. Not only does this provide a clear description of the behaviour of R eo connectors in terms of synchronisation and data flow constraints, it also paves the way for new implementation techniques based on constraint satisfaction. We also demonstrate that this approach is more efficient than the existing techniques based on connector colouring.