The Conceptual Basis for Mediation Services

Abstract

Mediator modules comprise a layer of intelligent middleware services in information systems, linking data resources and application programs. Earlier programs that led to the concept of mediation were either constructed to support specific applications or provided extended services from databases. Intelligent mediators are being built now by careful domain knowledge acquisition and hand crafting the required code. In this paper we present the conceptual underpinning for automating the mediation process. Automation does not extend to fully automatic code generation, since additional knowledge is necessary to provide added value. The generation concept is based on the extraction of a hierarchical domain model out of the general network representing the available resources. Associated with the method are domain ontologies. Ontologies list the terms used by the models, and document their relationships. These terms provide the semantic foundation needed to perform the generation. This paper is prescriptive, rather than a research report. The objective of publishing it now is to gain conceptual coherence among the projects that have adopted a multi-layer information architecture, while any implementations will differ greatly. Eventually having a limited number of interface standards will be essential, but these require a common base of understanding and technology.