A middleware for adaptive service orientation in pervasive computing environments

As enterprises become more mobile, the need for a pervasive computing environment where their applications "follow the user" becomes increasingly important. This can be achieved by the client side simply adapting to changes in the environment (caused by mobility) by rebinding to equivalent services in the new environment or by choosing "'more suitable"' services as the operating context changes. However, the static, hard-wired nature of today's enterprise applications does not lend itself well to such dynamism. Service orientation provides a promising foundation for such computing models, where services are stateless and can be replaced on the fly. Much more needs to be done though - service orientation needs to be made adaptive where rebinding happens automatically driven by triggers caused by context changes. This impacts both the programming model that developers use to express the flexibility as well as the runtime (middleware) that interprets this expression and acts upon it. In this paper, we present a programming model and run time architecture for adaptive service orientation based on semantic descriptions of services and service elements (tasks) augmented with contextually dependent resource-based requirements.