Towards a policy-driven framework for adaptive Web services composition

The variation of contexts in which a Web service could be used and the resulting variation in functional and Quality of Service (QoS) requirements motivates further research to extend Web services platforms to cater for differentiated service offerings and dynamic adaptability. Adaptability is an important requirement in the context of Web services to cater for the need of diverse set of client applications requesting customized view of consumed Web services to fit their own contexts and preferences. This paper presents an ongoing project to devise a novel service composition framework, named AdaptiveBPEL that leverages Aspect-Oriented Software Development (AOSD) techniques to "open up" the service composition for dynamic change in order to provide a greater degree of configurability and dynamic adaptability of Web services. This framework can: 1) easily adapt to changes in business rules, and collaboration policies governing service interactions 2) provide different levels of functional and QoS offerings. The adaptation process is policy-driven to declaratively define the adaptive service behavior through dynamic injection of functional and non-functional extensions into a core service composition to allow on-demand and perinstance service adaptability.