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
.