Virtual Database Engine component for constructing transient and/or materialized Linked Data views over external RDF data sources -- this includes in-built middleware (aka. "Sponger") for turning basic RDF into 5-Star RDF based Linked Data. Naturally, these views function like native Virtuoso RDF store documents (named graphs) which are then accessible for SQL, SPARQL, and SPASQL based query access using HTTP, ODBC, JDBC, OLE-DB, ADO.NET, and XMLA.