Efficient Replanning Technique for QoS-aware Web Service Composition

Abstract

A Web service is a service provided by software systems to support machine to machine inter-operations over Web. Given a set of Web services and a goal, the QoS-aware Web service composition problem constructs a composite Web service with the optimal accumulated QoS value, which satisfies the given goal specification. However, in the real world environment, frequent changes happen inherently - for instance, temporary machine down, heavy system workload, and network failure. If the solution we have constructed is not valid anymore due to the changes, we have to solve a new problem again. Ordinary approaches to find a new solution from scratch may waste computation time, since they explore the whole searching space again. Hence, in this paper, we propose a novel replanning algorithm, which does not solve the new composition problem from scratch but explores only the changed space to identify the new optimal solution. In the experiment, our replanning algorithm can deal with the composition problem much faster than the original algorithm to solve from scratch.