RDF Data Access Providers (Drivers) Sponger & Cartridges Explained Both the Sponger and Cartridges are middleware. If you are familiar with ODBC or JDBC, think of the Sponger as the Driver Manager (interface layer). The Cartridges are drivers. The Sponger delegates work to the Cartridges, and the Cartridges perform the RDFization.There are 2 types of Cartridges: Basic Cartridge - which generates an RDF Linked Data Graph without performing any lookups Meta Cartridges - which performs lookups via a binding layer to a plethora of Web 2.0 APIs e.g. New York Times, Open Calais, Zemanta, Del.icio.us, and many others . Additional Reading: Extracting RDF Structured Data from Non-RDF Sources Virtuoso Sponger Movie showing meta cartridges in action