XTM Topic Maps (ISO 13250) is a Semantic Web-related technology using XML to describe knowledge structures. A number of start-up companies in Europe and the US in the early 2000s initiated programmes to develop applications supporting the creation and navigation of Topic Maps. Of them, only Ontopia in Norway seems to have survived in any commercial sense, with its Ontopia Knowledge Suite (OKS) incorporating the Omnigator Topic Map navigator and Ontopoly Topic Map editor. Despite a committed cadre of enthusiasts across the globe (including myself), Topic Maps as a knowledge organization technology proved difficult to promote outside of Norway. As a result, Ontopia was acquired by Norwegian IT consultancy Bouvet ASA in March 2007.
Bouvet themselves have now acknowledged that Topic Maps does not appear to be a technology with any conventional commercial potential. They have therefore announced that the Ontopia suite of Topic Maps applications is to be made open-source. In my view, this is the best decision they could have made. Topics Maps is an XML mark-up standard with more readily understandable semantics and far greater flexibility for describing the widest variety of knowledge structures than is RDF, as adopted by the Semantic Web developers.
Visit the Ontopia site for further information.