The IRO-DB approach: processing queries in federated database systems

As information may be spread over several distributed and heterogeneous databases (DBs) the expectation for integrated access to them in a comfortable way arises. IRO-DB (Interoperable Relational and Object-Oriented DBs) is a federated database system (DBS) that provides interoperability among multiple heterogeneous autonomous DBs. Despite participating in the federation, the different DBs may keep their autonomy: on the one hand to be able to run existing applications without changing them, and on the other hand because severe reasons may support the decision for distributed DBs. An overview of IRO-DB is given. The architecture and the schemata available in IRO-DB are described and a focus on the treatment of queries in IRO-DB is given. IRO-DB is supported partly by the European ESPRIT III program under project number 8629.