Transparent reconfiguration of processes using compensation paths

In this paper we present new results in the area of reconfiguration of software systems in the presence of faults. More precisely, we consider a set of servers/processes that have the same functionality, i.e., are able to perform the same tasks and provide the same set of services to the clients of the system. When several of them turn out to be faulty, we want to be able to reconfigure the system so that the clients of the faulty servers/processes are serviced by some other fault free servers of the system in a way that is transparent to all the clients of the system. We propose a new method for reconfiguring in the presence of faults using compensation paths, which is an efficient way of shifting spare resources from where they are available to where they are needed. We also present optimal, simple reconfiguration algorithms of low polynomial time complexity that guarantee real time reconfiguration of the system.