Kowari is an Open Source, massively scalable, transaction-safe, purpose-built database for the storage, retrieval and analysis of metadata. Kowari is written in Java. Kowari supports RDF and OWL metadata.
J. Broekstra, A. Kampman, and F. van Harmelen. Proceedings of the first International Semantic Web
Conference (ISWC 2002), 2342, page 54--68. Sardinia, Italy, Springer Verlag, Heidelberg Germany, (June 2002)See also http://www.openrdf.org/.