Incorporating Semantic Relationships into an Object-Oriented Database System

Semantic relationships, those class-to-class connections that carry inherent support for constraints and various other functionalities, play an important role when building information models for applications. This is true whether one employs traditional data modeling techniques, knowledge-representation languages, or object-oriented modeling methodologies. An example of such a semantic relationship is the part-whole relationship. In fact, most of the popular object-oriented modeling approaches include such constructs in their repertoire of data modeling primitives. However, commercial object-oriented database (OODB) systems ordinarily do not provide built-in support for them. In this paper, we present a methodology by which a semantic relationship can be incorporated into an existing OODB system. At first, we give an overview of the general methodology for carrying out this integration task. Then, in order to ground our work in a real system, we show the addition of a part-whole semantic relationship to the ONTOS DB/Explorer OODB management system. This implementation is currently up and running, and an example application demonstrating its use is available on the Web.