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 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.