We present detailed implementation experiences from two commercial projects that has made extensive use of Semantic Web technologies at all levels in the architecture. The first project was a free software project ordered by Oslo Municipality to provide a common Semantic Web framework to improve access to quality controlled Web resources. The project, called Sublima was discussed by Engels and Norheim in their paper and poster at the International Semantic Web Conference in 2008.
The Sublima code-base has been extended for the Media Zone project, ordered by Oslo Public Library. The latter project will place multimedia terminals in libraries where Semantic Web technologies are used to help users navigate on a touch-screen display with graphical representations of topic and resource relations.
Key issues in these projects included building a flexible system where framework users could influence the queries sent to the backend in simple HTML forms. We insisted that the semantics should be preserved as far up in the stack as practically possible, and finally XSLT was used on a constrained RDF/XML serialisation for presentation. The projects evaluated SKOS vs. OWL DL for the topic graphs, which resulted in SKOS being used in one project, OWL DL in the other. One project also required a support for the Contextual Query Language, and we evaluated several approaches to this problem.
We present the final delivery which consists of mostly free software implementing Semantic Web Technology and W3C standards. The flexibility of the system allows it to be fitted to many domains, and its suitability for a knowledge organisation system for astronomy is discussed. In particular, we focus on SKOS-based thesauri, and on non-hierarchal semantic relations. Finally, we consider possible extensions that use Linked Data concepts to astronomical data and their sources.