Federating Object-Oriented and Relational Databases: The IRO-DB Experience

From the beginning of 1994 to the end of 1996, the IRO-DB (Interoperable Relational and Object-Oriented Databases) ESPRIT project has developed tools for accessing relational and object-oriented databases in an integrated way, and for designing and maintaining integrated applications on large federations of heterogeneous databases. IRO-DB is based on the ODMG pivotal object model and gives an OQL/OML-C++ interface to users on a federation of relational and object-oriented databases. This paper summarizes the main problems and choices done during the system design, describes the IRO-DB architecture and components, presents the project's achievements and gives a synthesis of the lessons learned during the project's development. It also introduces future plans for the system.