The term Service Oriented Architecture describes a vision in which a large number of services are available via standard Internet protocols and applications can be assembled in a fast and flexible way an top of these services. We argue that the semantics of service behavior and policies need to be made explicit in order for this vision be become a reality. We propose a unified declarative framework for modeling policies, goals, pre-, and post-conditions, which allows for a more dynamic interaction between requester and provider. Specifically, we show how policies can be used to select a suitable provider and how a requester can invoke a service without prior knowledge of the required parameters and message formats. Most notably, our framework is embedded within the standard web service technologies.
© Copyright by K.G. Saur Verlag 2004