language: en

[ACM SIGPLAN Workshop on Languages, Compilers and Tools for Real-Time Systems, La Jolla, California, June 1995.]

RTsynchronizer: Language Support for Real-Time Specifications in Distributed Systems

Shangping Ren and Gul A. Agha
Department of Computer Science
1304 W. Springfield Avenue
University of Illinois at Urbana-Champaign
Urbana, IL 61801, USA
Email: { ren � agha }@cs.uiuc.edu

Abstract 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.

[The research described has been made possible by support from the Office of Naval Research (ONR contract numbers N00014-90-J-1899 and N00014-93-1-0273), by an Incentives for Excellence Award from the Digital Equipment Corporation Faculty Program, and by joint support from the Defense Advanced Research Projects Agency and the National Science Foundation (NSF CCR 90-07195).]

[The authors would like to thank Mark Astley, Brian Nielsen, Masahiko Saitoh and Daniel Sturman for helpful discussions concerning the manuscript.]

1 Introduction