In this paper, the ReSpecT specification language for programming the behaviour of tuple centres is extended with the out_tc predicate, enabling communication between tuple centres. The extension is formally defined, and its benefits in the management of multiple coordination flows are outlined. The paper shows how relevant interaction scenarios – typically event-oriented – can be framed as multiple coordination flow problems, and properly engineered using tuple centres with the extended ReSpecT language.
In particular, first ReSpecT is used to implement a well-known coordination primitive – copy-collect –, provided by some tuple-based model as a building block for managing multiple coordination flows; then the Publish/Subscribe interaction pattern is taken into account, showing how ReSpecT tuple centres can be used for the design of flexible event notification services. For sake of concreteness, two examples are then developed: a JavaSpaces- and T Spaces-like notification service, and a patient monitoring system, involving the notification of complex event patterns.