Component-Based Analysis of Fault-Tolerant Real-Time Programs

We focus on decomposition of fault-tolerant real-time programs that are designed from their fault-intolerant versions. Towards this end, motivated by the concepts of state predicate detection and state predicate correction [1] for untimed systems, we identify three types of components, namely, detectors, weak -correctors, and strong -correctors. We also consider different levels of fault-tolerance, namely, soft-failsafe, hard-failsafe, nonmasking, soft-masking, and hard-masking, depending upon the satisfaction of safety, liveness, and timing constraints in the presence of faults. We show that depending upon the level of tolerance, fault-tolerant real-time programs contain one or more detectors and/or weak/strong- correctors