Fault-tolerance operators for distributed real-time control systems

The authors are concerned with fault tolerance at the level of the control programs written by the application designer. Their goal is to provide high-level architecture-independent facilities for allowing control programs running on a distributed computing system to tolerate failures of the underlying hardware and software design faults. The authors propose a model based on modular structuring of the application tasks, which permits building dependable control structures by the use of redundancy. The authors present an implementation of such an approach to fault tolerance based on the control language Syter and intended to support distributed real-time applications. This language provides various predefined operators to express sequential, synchronized, or parallel execution of processes, as well as the preemption and priority of some evolutions over others. Moreover, it offers a set of operators dedicated to fault tolerance, some of which are described