title: Rexster for Sparql over Titan + Cassandra
body: <p>I have been running a Titan graph db over Cassandra cluster. In this I have both blueprint graph and RDF graph. I am using rexster server for querying (gremlin) and visualization purpose with no problem. Now I want to do sparql query using rexster. </p>
  
  <p>I have enabled sparql extension in rexster but when I run a sparql query it complains about underlying graph. Exact error is this.   </p>
  
  <pre><code>{"message":"the graph to which this extension is applied is not a SailGraph implementation","api":{"description":"execute SPARQL queries against a SAIL graph."....
  </code></pre>
  
  <p>Is there a way to tell rexster that graph stored in Cassandra does have Sail compatible graph?</p>
  
  <p>PS: I have no problem in sparql query using sail apis in my code it just that I want an interface like Rexster for sparql query</p>