Design and implementation of context-information virtualization and integration layers for wireless sensor networks

Context-aware systems [32] provide to application developers and to end-users new kinds of applications, that can adapt their behaviour according to context- information. These systems adapt their operations to the current context without explicit user intervention, thus increasing the flexibility and the efficiency of the system. The context-aware systems modify their behaviour according to several environmental attribute changes. There are different context-aware definitions, in 1992 Want et al. introduced the Active Badge Location System designed to determine the user location and to forward user calls to the nearest user phone. In 1994 Schiltit and Theimer defined the context as location, identities of nearby people, objects and changes to those objects. Dey and Abowd [33] refer to context as "any information that can be used to characterize the situation of entities (i.e., whether a person, place or object) that are considered relevant to the interaction between a user and an application, including the user and the application themselves".