A Simple Formal Method to Synthesize an Orchestrator in Web Service Composition

We study the following web service composition problem: given existing web services S-1, ... , S-n and a desired web service S-0, the objective is to synthesize an orchestrator Orch that coordinates S-1, ... , S-n so that S-0 is provided. We develop a simple input-output automata-based method that solves this composition problem. We also study whether the desired service S-0 is totally or partially provided by the system ((S-i)(i=1 ...) (n), Orch). The studied problem can be seen as a control problem, where Orch is a controller that restricts the behaviors of S-1, ..., S-n so that the controlled system conforms to S-0.