A methodology for semantically enriching interoperable databases

Abstract

Integrated access to a Federated Database System, whatever its architecture is, requires a deep knowledge about the semantics of its component databases so that interdatabase semantic relationships can be detected. Unfortunately, very often there is a lack of such a knowledge and the local schemas, being semantically poor as a consequence of the limited expressiveness of traditional data models, do not help to acquire it. The solution to overcome this limitation is to upgrade the semantic level of the local schemas through a semantic enrichment process that discovers implicit knowledge and makes it explicit by converting the local schemas to rich schemas expressed in a canonical model. Here we present a methodology for semantic enrichment consisting of two phases. In the knowledge acquisition phase, restrictions in the form of different kinds of identifiers and dependencies are discovered by analysing the intension and the extension of the database. Then, in the conversion phase, the schemas augmented with this knowledge are converted to rich schemas expressed in a canonical object oriented model.