Composition-oriented Web Service Discovery

Web services are emerging as a promising technology for the development of next generation distributed heterogeneous software systems. Some prominent challenges for Web services are the discovery of services which match some given requirements, the composition of services into new complex applications, and the safe replacement of (sub)services.The primary objective of this thesis is to define a suitable technique for a semantics- and behaviour-aware service discovery, capable of satisfying complex client requests which specify the ontology-annotated inputs and outputs, and (possibly) the expected behaviour of the service to be found.We tackle the discovery, composition and replacement of services advertised by OWL-S descriptions. First, we present a functional analysis that automatically generates sets of services satisfying the functional requirements of client requests. Next, we describe a behavioural analysis that generates a non-locking composite service by suitably composingthe services in a given set. A notion of behavioural congruence for Web services is introduced to check whether the composite service satisfies the behavioural requirements of the query.