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Object-oriented database systems (ooDBMSs) are supposed to offer at least the functionality available in commercial relational DBMSs of today. One important consequence of this is that they have to provide a separation of the global (conceptual) database schema from the external schema (" subschema ") of a particular task. Views are a mechanism to realize(More)
We argue for avoiding database reorganizations due to schema modification in object-oriented systems, since these are expensive operations and they conflict with reusing existing software components. We show that data independence, which is a neglected concept in object databases, helps to avoid reorganizations in case of capacity preserving and reducing(More)
This paper addresses the problem of deening views that span several ob-jectbases. Views are expressed in terms of an object algebra. We are interested in the degrees of coupling and in the degrees of integrity maintained through multi-objectbase views. A key issue is the problem of global object identity. Each local system has its private object identiiers(More)
This paper describes the architecture of OPERA, a generic platform for building distributed systems over stand alone applications. The main contribution of this research eeort is to propose a \kernel" system providing the \essentials" for distributed processing and to show the important role database technology may play in supporting such functionality.(More)