Obi-Wan is a RDF data integration system I developed during my thesis.
Creating a SPARQL endpoint
Currently Obi-Wan only supports conjunctive queries, but it may be possible to extends it using Jena ARQ as explained here. It got this idea from the D2RQ systems, which seems to do it (look at this class).
Then Jena Fuseki can be used as a SPARQL endpoint.
Or maybe the best solution is to use rdf4j.