Behavioral Description Based Web Service Composition Using Abstraction and Refinement

The Web Service Composition (WSC) problem with respect to behavioral descriptions deals with the automatic synthesis of a coordinator web service that controls a set of web services to reach a goal state. Despite its importance, however, solving the WSC problem for a general case (when the coordinator web service has only partial observations) remains doubly exponential in the number of variables in web service descriptions, rendering most attempts to compute an exact solution for modest size impractical. Toward this challenge, in this paper, we propose two novel (signature preserving and subsuming) approximation-based approaches using abstraction and refinement. Given a set of web service behavioral descriptions and a reachability goal, we automatically construct abstract web services which have less variables using over-approximation. If our method identifies a coordinator web service, the coordinator is guaranteed to control the given web services to reach the goal state no matter how they behave. Otherwise, our method refines the current abstraction by adding some variables that have strong dependency on the goal variables. We empirically validate that our proposals can solve realistic problems efficiently.