Automated repair of complex systems by fault compensation

A formal method used to repair discrete-event systems consisting of communicating processes is described. Two mechanisms of repairing faulty systems are proposed: the first inserts a new “compensator module” into the communication channel between the faulty process and one or more of its neighbors; the second modifies a neighbor of the faulty process in a compensating manner. The two mechanisms fall under a class of methods in which faults are not fixed by replacement of a faulty unit with a fault-free one, but where changes to the non-faulty parts of the system repair the system. A finite-state model is used to describe processes, and the problem is solved for two models of communication: the symmetric (or the handshake) model and, an asymmetric model. The algorithm is described, and examples are presented, including an indication of how the approach may be applied as part of a sophisticated fault management system for communication networks