Large-scale interoperability of legacy object bases

In this paper, we present a truly object-oriented approach to large-scale interoperabil-ity of heterogeneous and autonomous databases. The problem with such an environment is that users typically have limited insight into the semantics of data deened in foreign databases. We show that existing schema integration techniques are not quite suited to such environments, due to diiculties in determining the real-world entity modelled by a class from its deenition alone. In our approach, objects rather than classes are considered to be the fundamental unit of integration. The integrated class hierarchy is a result of the relationships between local and foreign objects rather than being deened explicitly. In other words, we compare class hierarchies based on the objects they classify only. We argue that in large-scale data interoperation, deening relationships between local and foreign objects is more applicable than deening relationships between classes.