Up-scaling a semantic navigation of an evidence-based medical information service on the Internet to data intensive extranets

While surfing through the World Wide Web, the user typically has to deal with a broad range of heterogeneity, not only with respect to contents but also to conceptual structure which is particularly reflected by the hyperlink structure. Supported by the protagonists of the Semantic Web, ontology-based approaches to structuring parts of the Internet or intranets have recently gained attention. These approaches usually rely on internal annotation of Web pages. Since it is not easy to commit distributed Web authors on a common terminology and correct syntax for annotation, internal annotation requires central access to all Web pages of interest. Therefore, the approach is well suited for (closed) intranets but not for the open Internet. In contrast, the article presents an ontology based approach to external annotation of Web pages. External annotation yields the advantage that existing documents need not to be edited, and therefore is potentially applicable to parts of the Internet which cannot be controlled. This approach is applied in order to up-scale a prototype semantic navigation of an evidence based medical information service on the Internet, running at a relatively small scale, to data intensive extranets.