Automatic Service Composition and Invocation of Semantic Web Services

Web Services are viewed as a new paradigm for building distributed web applications. The W3C defines web services as a programmatic interface that enables communication among applications. OWL-S (earlier known as DAML-S) is an initiative that aims to describe web services using semantic web languages like RDF, RDFS and OWL. The motive behind adding semantics is to enable automatic discovery, composition, invocation and execution monitoring. In this thesis, we look at the problem of web service composition { synthesizing complex tasks from a set of atomic (basic) tasks. We look at how a service description can be transformed into planning operators. We present a planner that uses a backward-chaining algorithm for the task of composition. We also discuss an algorithm for automatic invocation. The automatic invocation algorithm takes the plan generated by the planner and determines data required for invocation using queries. Finally, we discuss the architecture of our agent, which is capable of interacting with web services solely based on service descriptions.