A User-Reconfigurable Object-Oriented Geographic Database

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The aims of the research are to integrate the view providing mechanism and the extensibility realizing mechanism, and to provide the mechanism that reconfigures the database virtually for users.We proposed that utilization of a map, area of a map, and information level of a map (that corresponds to scale of a map) prescribe the view of a geographical database. Moreover, as the elements of the view instance in a object-oriented geographical database, we listed a set of objects that composes the view instance, and behavior of each object. We call the former "domain" and the latter "appearance". Utilization, area and information level of a map have each prescribing domain and appearance. The entire view is defined as a composition of each domain and appearance.Based on the above model, we designed a view creation mechanism. It is composed of two parts, i.e. a domain defining part and an appearance defining part. Moreover, it creates a set of proxy-objects based on domain and appearance defined here. Users operate the database via the set of proxy-objects.The virtually reconfigured database is able to hold extended-objects. Extended-objects contain extended data and methods that are necessary for a user, and delegate ununderstandable messages to the proxy-objects. Users can regard a set of proxy-objects and extended-object as a virtually reconfigured database.