RTsynchronizer: language support for real-time specifications in distributed systems

We argue that the specification of an object's functional behavior and the timing constraints imposed on it may be separated. Specifically, we describe RTsynchronizer, a high-level programming language construct for specifying real-time constraints between objects in a distributed concurrent system. During program execution, RTsynchronizers affect the scheduling of distributed objects to enforce real-time relations between events. Objects in our system are defined in terms of the actor model extended with timing assumptions. Separation of the functional behaviors of actors and the timing constraints on patterns of actor invocation provides at least three important advantages. First, it simplifies code development by separating design concerns. Second, multiple timing constraints can be independently specified and composed. And finally, a specification of timing constraints can be reused even if the representation of the functional behavior of actors has changed, and conversely.A number of examples are given to illustrate the use of RTsynchronizers. These examples illustrate how real-time constraints for periodic events, simultaneous events, exception handling, and producer-consumer may be specified.