Federations of UbiComp Environments

Business enterprises can proficiently benefit from Ubiquitous Computing (UbiComp). UbiComp environments enable mobile users to access services and resources in a transparent and spontaneous way; that is, without any configuration operation, by means of very friendly user-environment interface mechanisms and, sometimes, anticipating user needs. Unfortunately, until now the UbiComp model has always been applied to environments bounded to a singular physical site. In order to support large enterprises, which may have several offices spread over a wide geographic area, this model needs to be extended with basic services that enable the realization of federations of environments. In other words, in the case of multi-office enterprises, each office could be equipped with a classic UbiComp environment; but, such environments must be interconnected by the internet and co-ordinated by a set of higher level services. As a matter of fact, in this case mobile users not only have to get access in a transparent and spontaneous way; but also, they must have the possibility of leaving a physical site without concerning about their pending computations and, successively, they must be enabled to come back in the environment, even in a different site, and resume their computations. As a consequence, locating mobile users and handling their disconnections becomes a very critical requirement. Indeed, differently from a classic UbiComp environment, in a federation of UbiComps resources can not simply be released when a mobile user leaves. Instead, the global environment has to infer user's intentions in order to understand whether he will come back to resume computations, or not. In this paper, we propose a Web Services based architecture for federating classic UbiComp environments. This architecture supports large enterprises with functionalities for locating and tracking mobile users in a federation of UbiComp environments. These services implement specific strategies that have been devised to allow i) mobile users to leave a physical site without concerning their pending computations; ii) the global environment to locate and track users in the federation of UbiComp environments; iii) mobile users to come back in the federation and resume their computations; and iv) the environment to reliably handle resources by inferring users intentions.