Reliability analysis of CSP specifications - A new method using Petri nets

Theoretical models like CSP and CCS describe computation using synchronization. Such models define independent system entities or processes that cooperate by explicit communication. In safety critical systems these communications represent visible actions which, if they do not occur or are delayed beyond their deadline, will cause a failure to occur. This paper describes the basic methodology for converting a formal description of a system into the information needed to predict system behavior as a function of observable parameters. Currently under development is a tool to permit stochastic analyses of CSP-based system specifications. The CSP-based grammar used by this tool is presented and isomorphisms between CSP-based specifications and Petri net-based stochastic models are shown. A brief example of the translation between these two formalisms is given along with (1) an analytical derivation of timing failure probability and cost minimization, and (2) discrete and continuous time Markovian analysis which provide reliability predictions for candidate designs. The translation process is currently being automated.