A Federated Broker Architecture for Large Scale Context Dissemination

Dissemination of context data from context producing entities to context consuming entities is a fundamental functional task of context aware systems. Broker based approaches have been successfully demonstrated in a number of prototype context-aware systems. With the increase in sensing capabilities of mobile devices, such devices are not merely consumers of context information any more but also have the ability to be \emph{providers} of context gathered through integrated sensors. In such a provider-consumer model, where context dissemination is aided by a central broker, device-broker interaction can become a communication and computation bottleneck in presence of multiple context providers and consumers in mobile devices. In this paper we present a theoretical model for a large scale context-aware system based on a federation of multiple context brokers and discuss the concept of a mobile broker to facilitate the participation of mobile devices in context provision and consumption efficiently. The utilisation of an asynchronous event-based publish-subscribe paradigm is focused as a key element.