Synthesizing, an integrated ontology

To exploit the Internet’s expanding data collection, current Semantic Web approaches employ annotation techniques to link individual information resources with machine-comprehensible metadata. Before we can realize the potential this new vision presents, however, several issues must be solved. One of these is the need for data reliability in dynamic, constantly changing networks. Another issue is how to explicitly specify relationships between abstract data concepts. Ontologies provide a key mechanism for solving these challenges, but the Web’s dynamic nature leaves open the question of how to manage them. The Mediator Environment for Multiple Information Sources (Momis), developed by the database research group at the University of Modena and Reggio Emilia, aims to construct synthesized, integrated descriptions of information coming from multiple heterogeneous sources. Our goal is to provide users with a global virtual view (GVV) of information sources, independent of their location or their data’s heterogeneity. Such a view conceptualizes the underlying domain; you can think of it as an ontology describing the sources involved. The Semantic Web exploits semantic markups to provide Web pages with machine-readable definitions. It thus relies on the a priori existence of ontologies that represent the domains associated with the given information sources. This approach relies on the selected reference ontology’s accuracy, but we find that most ontologies in common use are generic and that the annotation phase (in which semantic annotations connect Web page parts to ontology items) causes a loss of semantics. By involving the sources themselves, our approach builds an ontology that more precisely represents the domain. Moreover, the GVV is annotated according to a lexical ontology, which provides an easily understandable meaning to content. In this article, we use Web documents as a representative information source to describe the Momis methodology’s general application. We explore the framework’s main elements and discuss how the output of the integration process can be exploited to create a conceptualization of the underlying domain. In particular, our method provides a way to extend previously created conceptualizations, rather than starting from scratch, by inserting a new source.