Cooperative middleware specialization for service oriented architectures

Service-oriented architectures (SOA) will provide the basis of thenext generation of distributed software systems, and have already gained enormous traction in the industry through an XML--based instantiation, Web services. A central aspect of SOAs is the looser coupling between applications (services) that is achieved when services publish their functional and non-functional behavioral characteristics in a standardized, machine readable format. In this paper we argue that in the basic SOA model access to metadata is too static and results in inflexible interactions between requesters and providers. We propose specific extensions to the SOA model to allow service providers and requestors to dynamically expose and negotiate their public behavior, resulting in the ability to specialize and optimize the middleware supporting an interaction. We introduce a middleware architecture supporting this extended SOA functionality, and describe a conformant implementation based on standard Web services middleware. Finally, we demonstrate the advantages of this approach with a detailed real world scenario.