Description Logics for e-Service Composition

e-Services represent a new model in the utilization of the network, in which self-contained, modular applications can be described, published, located and dynamically invoked, in a programming language independent way. Research on e-Services spans over many interesting issues, including description, discovery, composition. Our research focuses on automatic composition synthesis. More specifically, we have devised techniques that, given (i) a client specification (target e-Service) expressed as a transition system and (ii) a set of available e-Services, also described as transition systems, synthesizes a composite e-Service that (i) uses only the available e-Services and (ii) interacts with the client “in accordance” with the input specification. First, we have considered the situation where the target e-Service is completely specified, and then we have extended the framework to deal with a target e-Service which is underspecified and presents non-determinism, in the form of don’t care condition on the next transitions. Our techniques are based on reducing the problem of checking the existence of a composition into concept satisfiability in a knowledge base expressed in a Description Logic (DL) –or equivalently satisfiability of a formula in a theory expressed in a variant of Propositional Dynamic Logic. With this reduction, reasoning tools for DLs can be directly used for composition synthesis, in particular by extracting a composite e-Service from a model of the DL knowledge base. We have developed (and currently continue to extend) an open source prototype system, that realizes our techniques, which is, at the best of our knowledge, the first effective tool for automatic composition synthesis of e-Services that export their behavior.