A Web Services Based Architecture for Supporting Mobile Users in Large Enterprises

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 and through very friendly user-environment interface mechanisms which sometimes anticipate user needs. Unfortunately, until now the UbiComp model has been applied only to environments bounded to a specific 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 multioffice enterprises, each office could be equipped with a classic UbiComp environment; however, 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 should have the possibility of leaving a physical site without concern of their pending computations and, successively, they should 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 be merely 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 with no concern of 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.