Joseph Sifakis
Verimag, Grenoble, France


Modeling Real-time Systems

Modeling real-time systems raises non-trivial problems for the definition of usable modeling languages and the application of model-based development approaches.

We identify key problems and present corresponding research directions for the incremental construction of timed models for real-time systems.

We present a framework that may provide some solutions and an associated methodology for model construction. Timed models of real-time systems are obtained by adding timing constraints to their application software. These constraints take into account execution times of atomic statements, the dynamics of the external environment, as well as quality of service requirements. The framework combines two kinds of composition operators for timed components:

We show that the combination of parallel composition and restriction operators allows compositional modeling of real-time systems, in particular of aspects related to heterogeneous interaction and execution, resource sharing and scheduling. Scheduling policies are modeled by dynamic priorities. The framework supports composition of scheduling policies and provides compositionality and composability results for deadlock-freedom of scheduled systems.

We show applications of these results, including model-based development of applications in Esterel and real-time Java, as well as a partial implementation of the framework in Verimag's IF toolset.



Joseph Sifakis is CNRS researcher and the Director of the Verimag Laboratory, in Grenoble, France. He studied Electrical Engineering at the Technical University of Athens and Computer Science at the University of Grenoble. Joseph Sifakis worked on both theoretical and practical aspects of Concurrent Systems Specification and Verification. He contributed to the development of the state of the art in verification methods and tools by model checking for both untimed and timed systems. His current research interests include modeling, design and analysis of real-time systems with focus on composability and compositionality. Joseph Sifakis is the scientific coordinator of the European Network of Excellence ARTIST2 on Embedded Systems Design.

Last updated on 23 September 2004 by JHA.