Building an Ontology with MOMIS

Nowadays the Web is a huge collection of data and its expansion rate is very high. Web users need new ways to exploit all this available information and possibilities. A new vision of the Web, the Semantic Web , where resources are annotated with machine-processable metadata providing them with background knowledge and meaning, arises. A fundamental component of the Semantic Web is the ontology; this “explicit specification of a conceptualization” allows information providers to give a understandable meaning to their documents. MOMIS (Mediator envirOnment for Multiple Information Sources) is a framework for information extraction and integration of heterogeneous information sources. The system implements a semi-automatic methodology for data integration that follows the Global as View (GAV) approach. The result of the integration process is a global schema, which provides a reconciled, integrated and virtual view of the underlying sources, GVV (Global Virtual View). The GVV is composed of a set of (global) classes that represent the information contained in the sources. In this paper, we focus on the MOMIS application into a particular kind of source (i.e. web documents), and show how the result of the integration process can be exploited to create a conceptualization of the underlying domain, i.e. a domain ontology for the integrated sources. GVV is then semi-automatically annotated according to a lexical ontology. With reference to the Semantic Web area, where generally the annotation process consists of providing a web page with semantic markups according to an ontology, we firstly markup the local metadata descriptions and then the MOMIS system generates an annotated conceptualization of the sources. Moreover, our approach “builds” the domain ontology as the synthesis of the integration process, while the usual approach in the Semantic Web is based on “a priori” existence of ontology