Diagnosing Distributed Systems Modeled by Communicating Finite State Machines

We propose a diagnostic algorithm for the case where a distributed system specification (implementation) is given in the form of communicating finite state machines (CFSMs). Such an algorithm localizes the faulty transition in the distributed system once the fault has been detected. It generates, if necessary, additional diagnostic test cases which depend on the observed symptoms and which permit the location of the detected fault. The algorithm guarantees the correct diagnosis of any single (output or transfer) fault in a system of communicating FSMs. A simple example is used to demonstrate the functioning of the different steps of the proposed diagnostic algorithm.