Distributed Context-Aware Systems

Currently, context-aware applications are dened as applications that react appropriately to information sensed in the environment, as opposed to applications that elaborate only information explicitly provided by users. Context is (implicitly or explicitly) thought of as a collection of features of the (physical or virtual) environment which can aect the behavior of an application. Though this notion of context is relatively unproblematic in systems with central control, it raises a number of challenging issues when applied to distributed systems, namely systems in which control is distributed over a group of heterogeneous, autonomous, interacting entities (typically, agents). Indeed, in distributed applications, we cannot assume that autonomous entities share a context, even though each of them uses contextual information for its operations. In this essay, we discuss in detail this claim and present a notion of context which seems to be adequate for distributed systems. For the sake of illustration, we outline how this notion of context can be used to design distributed context-aware systems. 1