Behavior Based Service Composition

To enable flexible leveraging of the growing plethora of available web services, service clients should be automatically composed based on required behavior. In this paper, we present a foundational framework for behavior based composition. Services advertise their behavior as labeled transition systems with the action labels corresponding to their externally invocable operations. Query logics are defined in a simple extension of μ-calculus with modalities in which variables are allowed to occur. Query logics specify the desired behavior of the composition with the variables standing for the programs that need to be synthesized. We define a special subclass of programs, called deterministic and crashfree, which behave deterministically (even if the services used are nondeterministic) with all program steps successfully executing in whichever state the services may be in during entire execution. We present an algorithm that synthesises deterministic and crash-free programs whenever there exists such a solution. Since the μ-calculus is the most expressive logic for regular properties, our results yield a complete solution to the automatic composition problem for regular behavioral properties.