Abstract:

A truly concurrent and timeless semantics is proposed for a composition (network) of sequential, non-deterministic processes with asynchronous communication. It is shown when this semantics differs from simple interleaving. Implementation-dependent time constraints determine a subset of all computations of the timeless semantics. This subset is precisely characterized for a network of processes and a given set of constraints. It is shown how the same subset may be generated by a timed transition system, i.e., how to simulate a real-time and concurrent system by a non- deterministic and sequential one.

The model for which the above results are obtained, corresponds to that of Estelle with processes being represented by Estelle modules (without nesting). It is more general in that it doesn't limit the communication between modules to port-to-port communication (it allows for arbitrary multicasting) and it doesn't restrict the communication buffers to (infinite) FIFO queues as it is in Estelle.