Middleware Services for Federating UbiComp Environments

The Ubiquitous Computing model, which has always been applied to environments bounded to a singular physical site, has now to scale to large enterprises that have several offices, spread over a wide geographic area, each one equipped with an own WLAN, and interconnected by the internet. In this case, it is possible to architect the environment as a federation of classic UbiComp environments i. e., each physical site is equipped with an UbiComp environment. All UbiComp environments are federated and coordinated in order i) to compose a wide-area, virtually unique, UbiComp environment and ii) to provide mobile users with access to a set of integrated application services, with a unique interface model, independently of the physical site they are in. In this paper, a set of basis services that implement a federation of UbiComp environments is presented. The resulting environment has mechanisms for locating and tracking mobile users in all the physical sites of the environment. It is also equipped with an advanced session manager service that enables mobile users to leave a site without concerning about pending computations and successively resume them from other sites.