WSDarwin: automatic web service client adaptation

The service-oriented architecture paradigm prescribes the development of systems through the composition of services, i.e., network-accessible components, specified by (and invoked through) their WSDL interface descriptions. Systems thus developed need to be aware of changes in, and evolve with, their constituent services. To support this coevolution process, we have developed WSDarwin, a toolkit that facilitates both providers and clients in the evolution of service-oriented systems. In this work, we focus primarily on the comparison of service-interface versions, in order to precisely recognize their differences, and the adaptation of client applications. We propose a lightweight model to represent service interfaces, an efficient and accurate comparison method whose output can be seamlessly consumed by the adaptation process, a classification of changes in service interfaces based on their impact on client applications and, finally, a generic adaptation algorithm that can be applied for any type of change and on any client regardless of the implementation technology. We demonstrate this part of the WSDarwin toolkit on a client application invoking several versions from the Amazon EC2 web service and we report on the challenges we faced.