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Unformatted text preview: Accessing information on demand af any location Mobile ~ n ~ o ~ f f ~ o n Access MAHADEY SATYANARAYANAN lie ability to access information on demand at any location confers competitive advantage on individuals in an increasingly mobile world. As users become more dependent on this ability, the span of access of data repositories will have to grow. The increasing social accep- tance of the home or any other location as a place of work is a further impetus to the development of mechanisms for mobile information access. These considerations imply that data from shared file sys- tems, relational databases, object-oriented databases, and other repdsitories must be accessible to programs running on mobile computers. For example, a technician servicing a jet engine on a parked aircraft needs access to engineering details of that model of engine as well as past repair records of that specific engine. Similarly, a businessman who is contin- uing his work on the train home from Manhattan needs access to his business records. Yet another example involves emergency medical response to a case of poisoning: the responding per- sonnel will need rapid access to medical databases describing poison symptoms and antidotes, as well as access to the spe- cific patients medical records to determine drug sensitivity. This article is a status report on the work being done by my colleagues and myself toward meeting such challenges. It begtns by describing a scenario that offers a tantalizing glimpse of the power of mobile information access. The major obstacles on the path toward this vision are then examined. The rest of the article is a summary of research on overcom- ing these obstacles in the context of the Coda and Odyssey systems. A Vision o f Tomorrow Imagine this hypothetical scenario of a business trip in the year 2000: You are sitting at your office desk, editing a report stored in a shared file system. The machine you are using is a small notebook computer, but it lets you use the larger and more comfortable display and keyboard on your desk via a tabletop infrared link. Soon it is time to leave for the airpoa. When the limousine arrives, you pick up your notebook and leave. On the ride to the airport you continue your work. Your notebook recognizes that it is no longer on a local area network (LAN), but continues communication with the sewers via a cellular modem. You finish your editing, save the file, and send mail to your coauthor letting him know that he can now review your edits. You then begin working on the slides for your talk in Paris. Upon arrival at the airport, you board your transatlantic flight and continue working. Although each seat is provided with an outlet for air-to- ground telephone service, your notebook inquires and discov- ers that telephone charges are very high. It therefore wisely decides to let you operate disconnected and to defer all com- munication until you have landed....
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- Fall '09