Virtuoso Universal Server is a middleware and database engine hybrid that provides an object-relational model.
The Virtuoso project started in 1998 from a merger of the OpenLink data access middleware and the [Kubl](/db/kubl) DBMS.
Object-Relational
Custom API SQL HTTP / REST
http://virtuoso.openlinksw.com/
FI
1998
Commercial
C
Kubl
GPL v2, Proprietary
https://en.wikipedia.org/wiki/Virtuoso_Universal_Server
Typhoon
