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.