Coordination by Timers for Channel-Based Anonymous Communications

In considering systems of distributed processes, we must deal with access to resources, locations and communication among processes. In this paper we present a new model for timed coordination of communicating distributed processes using an extension of the π-calculus with locations, types and timers. Types are used to express restricted access to distributed resources. Timers de ne timeouts for both communication channels and resources. Coordination is given by these timers, together with additional coordination rules. We de ne the syntax of the model and its operational semantics and then provide some results regarding the typing system and the timers. A timed barbed bisimulation relation is de ned to compare the processes in di erent settings. The timed coordination aspects are given through a coordinator pair. It consists of a timers assigning function which can be dynamically changed, and a set of coordination rules. Some illustrative examples are given. Finally we compare the new model with other existing coordination models.