Object Algebra and Views for Multi-Objectbases

This paper addresses the problem of de ning 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 main tained through multi objectbase views A key issue is the problem of global object identity Each local system has its private object identi ers OIDs to represent objects Globally however we need other mechanisms to uniquely refer to objects We propose a technique that is based on the de nition of updatable views Queries to other objectbases are used as a referencing mechanism The mechanism is useful as a formal basis for partial or complete schema integration in multi objectbase systems