摘要：The viewpoint concept has received widespread attention recently. Its integration into a data model improves the flexibility of the conventional object-oriented data model and allows one to improve the modelling power of objects. The viewpoint paradigm can be used as a means of providing multiple descriptions of an object and as a means of mastering the complexity of current database systems enabling them to be developed in a distributed manner. The contribution of this paper is twofold: to define an object data model integrating viewpoints in databases and to present a federated database system integrating multiple sources following a local-as-extended-view approach.
