Abstract

Preview

Despite the emergence of standards to define and compose Web Services to form more complex systems, as yet, there is little support for engineering systems composed from multiple services. As web technology has evolved, tools have been developed that support the design of both visual content and functional services for users. Web Services however, concentrate on the view of systems inter-operating with other systems rather than that of actual human actors, yet the concepts related to ease of design are still highly relevant. However, as yet, tools which assist service design and composition provide only basic capabilities. The main contribution of this work is to provide a rigorous approach to specifying, modelling, verifying and validating the behaviour of web service compositions with the goal of simplifying the task of designing coordinated distributed services and their interaction requirements. We address these issues through the use of rigorous software process analysis techniques. The thesis specifies semantics for web service composition standards and develops an accessible, mechanical tool, which automates the tasks involved. This thesis presents a model-based approach built upon formal verification, validation and simulation techniques, utilising scenario-based design and implementations built in service composition standards. The work assigns the semantics of compositions through the use of Labelled Transition Systems (LTS) in the form of Finite State Processes (FSP). A tool suite is also presented, forming an environment to assist in undertaking the approach, and featuring an extendable and flexible architecture for the variety of compositional standards that exist. The approach is validated using a case study as a result of collaborative work with the UK Police Information Technology Organisation (PITO) and through example compositions published by the International Business Machines Corporation (IBM).