Hi
I want to write an engine for processing SPARQL queries. i want to use jena to parse SPARQL queries and convert them to a internal form for my application. i can parse queries and convert them to query algebra using this code: Query q=QueryFactory.create("select ?s ?o where {?s ?p ?o }"); Op op = Algebra.compile(q) ; but i don't know how to use op and what is the uses of op.visit(opVisitor) . in more detail: i want to convert query to a left deep tree and then process query operators in a pipelined manner.