Towards a methodology for developing a federated database system

This paper proposes a methodology for developing a federated database system. This principle permits one to use several conjoined databases without defining any global schema. The bottom-up approach is based on the homogenization and the integration of pre-existing and heterogeneous database schemas. Autonomous component database systems participate in a federation by sharing their data. The method provides global integrated views called federated schemas. Our multibase prototype consists of a relational database and the object database ONTOS. The use of classes as the common data model allows one to manipulate complex data structures and to associate process to data during the steps of integration and view definition. The proposed algorithms perform the translation of the component schemas and control the consistency of the export schemas. A schema of classes is represented with a directed graph