Edinburgh Napier University

  View mechanisms play an important role in restructuring data for users, while maintaining the integrity and autonomy for the underlying database schema. Although far more complex than their relational counterparts, numerous object-oriented view mechanisms have been specified and implemented over the last decade. These view mechanisms have served different functions: view schemata for object oriented databases; object views of relational (and other) database systems, and the formation of federated schemata for distributed information systems. In the latter category there is still a significant amount of research required to construct a view language powerful enough to support federated views. Such a language (or set of languages) should support not only object views, but also a wrapper specification language for external information sources, and a set of restructuring and integration operators. Furthermore, with the advent of standard models and technologies such as CORBA for distribution, ODMG for storage, and XML for web publishing, these languages should be based upon, or cooperate with, these standards. In this research, we present a view mechanism which retains the semantic information incorporated in ODMG schemata, provide a set of operators which facilitate the restructuring and integration necessary to merge schemata, and provide wrappers to heterogeneous systems such as legacy systems, ODBC databases, and XML data sources.