Tuple-based Coordination Models in Event-based Scenarios

Tuple-based coordination models are a successful tool for harnessing the complexity of interactions in open and highly dynamic systems. Recently, coordination infrastructures such as JavaSpaces and TSpaces have been proposed for event-based systems as well, promoting the mechanism of event notification at the coordination level. In this paper we investigate how the foundation of tuple-based coordination models is affected by the idea of applying them to event-based scenarios. Since existing semantics models seem quite inadequate to this purpose, we present a new formal framework where the behaviour of the coordination medium is defined in terms of the events it produces and consumes. To stress the usefulness of our approach, we discuss how the formal framework can be used to extend the basic tuple-space model with the event notification mechanism. The application of coordination models to event-based systems also suggests to reconsider the traditional issue of coordination models' expressiveness. Correspondingly, we sketch a novel approach to characterise the expressiveness of a coordination medium.