Transforming relational database schemas into object-oriented schemas according to ODMG-93

Many database applications are currently confronted with the problem of migrating from relational to object-oriented systems. A central task in such a process is schema conversion, which so far has to be done in a way that specifically depends on the target system. Recently, the ODMG-93 proposal has established a framework in which the core aspects of an object-oriented schema can be made precise, so that it becomes possible to do schema conversions in a system-independent way, by using the ODMG model as target. This paper presents a methodology for transforming relational schemas into object-oriented ones according to ODMG-93, thereby rendering it possible to do reverse engineering computer-assisted, and to automize database migrations. Essentially, the methodology is a three-step process who first goal is to complete a given relational schema, i.e., to make the semantic information it carries as explicit as possible using a variety of data dependencies. A completed schema is then tranformed into an ODMG schema in a straightforward way, basically by generating classes from relation schemas. However, the result will in general not yet be optimal from an object-oriented perspective; so the initial object-oriented schema is finally improved to better exploit the options available in the object-oriented paradigm. (orig.)SIGLEAvailable from TIB Hannover: RO 7057(1995,11) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDeutsche Forschungsgemeinschaft (DFG), Bonn (Germany)DEGerman