code: @Override
  	public OntopOWLConnection getConnection() throws ReasonerInternalException {
  		if (!questready) {
  			OWLReasonerRuntimeException owlReasonerRuntimeException = new ReasonerInternalException(
  					"Ontop was not initialized properly. This is generally indicates, " +
  							"connection problems or error during ontology or mapping pre-processing. " +
  							"\n\nOriginal error message:\n" + questException.getMessage()) ;
  			owlReasonerRuntimeException.setStackTrace(questException.getStackTrace());
  			throw owlReasonerRuntimeException;
  		}
  
  		try {
  			OntopConnection conn = queryEngine.getConnection();
  			return new DefaultOntopOWLConnection(conn, inputQueryFactory);
  		} catch (OntopConnectionException e) {
  			// TODO: find a better exception?
  			throw new ReasonerInternalException(e);
  		}
  	}
docs: The caller is in charge of closing the connection after usage.
  (the reasoner is not responsible of connections)