A Declarative Approach to Agent-Centered Context-Aware Computing in Ad Hoc Wireless Environments

Much of the current work on context-aware computing relies on information directly available to an application via context sensors on its local host, e.g., user profile, host location, time of day, resource availability, and quality of service measurements. We propose a new notion of context which includes in principle any information available in the ad hoc network infrastructure but is restricted in practice to specific views of the overall context. The context of each view is defined in terms of data, objects, or events exhibiting certain properties, associated with particular application agents, residing on particular hosts, and part of some restricted subnet. Location, distance, movement profiles, access rights, and much more can be used in view specifications. The underlying system infrastructure interprets the view specifications and continuously updates the contents of user-defined views despite dynamic changes in the specifications, state transitions at the application level, mobility of hosts in the physical space, and migration of code among hosts. In systems that are large-scale in terms of both space and numbers of agents, this local restriction will prove necessary for providing timely context information to application agents.