At core, Virtuoso is a high-performance object-relational SQL database. As a database, it provides transactions, a smart SQL compiler, powerful stored-procedure language with optional Java and .Net server-side hosting, hot backup, SQL-99 support and more. It has all major data-access interfaces, such as ODBC, JDBC, ADO .Net and OLE/DB. Virtuoso has a built-in web server which can serve dynamic web pages written in Virtuoso’s web language (VSP) as well as PHP, ASP .net and others. This same web server provides SOAP and REST access to Virtuoso stored procedures, supporting a broad set of WS protocols such as WS-Security, WS-Reliable Messaging and others. A BPEL4WS run time is also available as part of Virtuoso’s SOA suite. Virtuoso has a built-in WebDAV repository. This can host static and dynamic web content and optionally provides versioning. The WebDAV repository is tested to interoperate with WebDAV clients built into Windows XP, Mac OSX and others and makes Virtuoso a convenient and secure place for keeping one’s files on the net. Further, Virtuoso provides automatic metadata extraction and full text searching for supported content types. OpenLink Virtuoso supports SPARQL embedded into SQL for querying RDF data stored in Virtuoso’s database. SPARQL benefits from low-level support in the engine itself, such as SPARQL-aware type-casting rules and a dedicated IRI data type.