Supervisor Aware Service Composition Framework: An Implementation and Evaluation

Abstract

In our previous work (Atampore et al., 2016b), we developed a novel supervisory control framework for automated composition of Web services. In the proposed framework, we modeled services that exchange messages and exhibit nondeterministic (runtime-dependent) behaviours based on runtime input. The objective is to synthesize a supervisor that interacts with a given set of Web services through messages to guarantee that a given specification is satisfied. The framework employs Labelled Transition Systems (LTSs) equipped with guards and data variables to model Web services and provides a technique to synthesize a controller. We modeled the interactions of services asynchronously and we used the guards and data variables to express certain preconditions which are then propagated from the system requirements through the overall composite service. In this paper, first, we present a prototype implementation of our automated web service composition framework proposed in our previous paper into a tool support: The implementation involves the following: (i) the translation of industrial Web service standard such as WS-BPEL in a formal language suitable for control synthesis; (ii) the implementation of all the proposed control synthesis algorithms in our previous work; (iii) the incorporation of runtime information into the supervisory control synthesis; and (iv) the translation of the formal language used in the synthesis back to its WS-BPEL equivalent. Second, we present the application and a preliminary evaluation of the proposed composition approach in terms of (i) its effectiveness for the generation of controllers for a composition problem and (ii) its applicability using two well-known small case studies.