Prototyping a Categorial Database in P/FDM

The relational data model uses set theory to provide a formal background, thus ensuring a rigorous mathematical data model with support for manipulation. The newer generation database models are based on the object{oriented programming paradigm, and so fall short of having a formal background, especially in some of the more complex data manipulation areas. We use category theory to provide a formalism for object databases, known as the product model. This paper will describe our formal model for the key aspects of object databases. In particular, we will examine how this model deals with three of the most important problems inherent in object databases, those of queries, closure and views. As well as this, we investigate the more common database concepts, such as keys, relationships, aggregation, etc. We will implement a prototype of this model using P/FDM, a semantic data model database system based on the functional model of Shipman, with object{oriented extensions.