From Relations and Nested Relations to Object Models

Relational, complex object, and object-oriented data models seem to establish three diverging directions and it appears hopeless to arrive at a new higher-level unifying data model as a new platform for the non-traditional applications as well as for the classical ones. In this paper, however, we give some evidence that recent object models can be considered as an evolution from classical ones. Specifically, we describe a first evolutionary path from relations through nested relations and complex objects to object networks. A second evolutionary path starts from the DBTG network model and shows how this is turned into an object network again. Thus, we conclude that the next generation object-oriented data models should integrate concepts from these predecessors. This enables compatibility, coexistence, and cooperation between the different systems as well as a possible migration path, and may lead to a new overall data model platform for application development