SPARQL

“SPARQL is a recursive acronym and stands for SPARQL Protocol and RDF Query Language). It is an RDF query language, that is, a semantic query language for databases, able to retrieve and manipulate data stored in Resource Description Framework (RDF) format.”

~ Wikipedia on SPARQL

Copyleft or free-of-charge implementations of SPARQL endpoint ability producing software alternatives

• w:Virtuoso Universal Server - http://virtuoso.openlinksw.com/download/