Virtuoso Universal Server
Virtuoso Universal Server is a middleware and database engine hybrid that combines the functionality of a traditional RDBMS, ORDBMS, virtual database, RDF, XML, free-text, Web Application Server and File Server functionality in a single server product offering. Rather than have dedicated servers for each of the aforementioned functionality realms, Virtuoso is a “universal server”; it enables a single multithreaded server process that implements multiple protocols. The open source edition of Virtuoso Universal Server is also known as OpenLink Virtuoso. The software has been developed by OpenLink Software with Kingsley Idehen and Orri Erling as the chief software architects. Virtuoso provides an extended object-relational model, which offers all the flexibility of relational access with inheritance, run time data typing, late binding, and identity based access.
