/**
 * Create an LDPathWrapper Object
 * @param backend the linkeddata backend
 */
public LDPathWrapper(final LDCacheBackend backend) {

    // Register the Sesame RDF Parsers manually
    // TODO: use the OSGi service registry as described in:
    // http://blog.osgi.org/2013/02/javautilserviceloader-in-osgi.html
    RDFParserRegistry.getInstance().add(new RDFXMLParserFactory());
    RDFParserRegistry.getInstance().add(new NTriplesParserFactory());
    RDFParserRegistry.getInstance().add(new TurtleParserFactory());
    RDFParserRegistry.getInstance().add(new N3ParserFactory());
    RDFParserRegistry.getInstance().add(new SesameJSONLDParserFactory());
    RDFParserRegistry.getInstance().add(new RDFJSONParserFactory());
    RDFParserRegistry.getInstance().add(new SesameRDFaParserFactory());
    RDFParserRegistry.getInstance().add(new TriGParserFactory());
    BooleanQueryResultParserRegistry.getInstance().add(new SPARQLBooleanXMLParserFactory());
    TupleQueryResultParserRegistry.getInstance().add(new SPARQLResultsXMLParserFactory());

    ldpath = new LDPath<Value>(backend);
}
 

/**
 * test get Graph Query.
 * @throws Exception The test would fails if Exception occurs
 */
@Test
public void testGraphQuery() throws Exception {
	//insert some statments first
	for (final String tripleAsString : _data) {
		final Statement triple = parseNX(tripleAsString).iterator().next();
		TRIPLE_STORE.addData(triple);
	}
	//test Graph Query
	String queryString = "SELECT ?x ?y WHERE { ?x ?p ?y } ";
	String uri = BASE_URI + Protocol.REPOSITORIES + "/" + REPO_ID;
	File tmp = WebTestUtils.tmpFile();
	final ServletOutputStream servletOutputStream = new StubServletOutputStream(tmp);
	final HttpServletRequest request = mockHttpRequest(uri, METHOD_POST);
	when(request.getContentType()).thenReturn(MIMETYPE_WWW_FORM);
	when(request.getParameter(Protocol.QUERY_LANGUAGE_PARAM_NAME)).thenReturn(QueryLanguage.SPARQL.toString());
	when(request.getParameter(Protocol.QUERY_PARAM_NAME)).thenReturn(queryString);
	when(request.getParameter(Protocol.ACCEPT_PARAM_NAME)).thenReturn("application/x-binary-rdf-results-table");
	Vector<String> vec = new Vector<String>();
	when(request.getParameterNames()).thenReturn(vec.elements());
	when(request.getCharacterEncoding()).thenReturn(UTF_8);
	final HttpServletResponse response = mock(HttpServletResponse.class);
	when(response.getOutputStream()).thenReturn(servletOutputStream);


	_classUnderTest.service(request, response);
	
	Set<TupleQueryResultFormat> tqrFormats = TupleQueryResultParserRegistry.getInstance().getKeys();
	TupleQueryResultFormat format = TupleQueryResultFormat.matchMIMEType("application/x-binary-rdf-results-table", tqrFormats);
	TupleQueryResultParser parser = QueryResultIO.createParser(format, valueFactory);
	FileInputStream in = new FileInputStream(tmp);
	BackgroundTupleResult tRes = new BackgroundTupleResult(parser, in, null);
	parser.setQueryResultHandler(tRes);
	parser.parseQueryResult(in);
	assertTrue(tRes.hasNext());
	verify(response).setStatus(HttpServletResponse.SC_OK);

	servletOutputStream.close();
}
 

/**
 * Return an accept header which establishes a preference pattern for
 * solution set data. The accept header will not include any formats for
 * which we can not discover a parser.
 * <p>
 * Note: You CAN NOT just combine the accept headers for boolean results and
 * solution sets together because the boolean format overlaps the solution
 * set format (they are both [application/sparql-results+xml] so putting
 * them together blurs the quality annotations.
 */
public static String getDefaultSolutionsAcceptHeader() {
   
    // Copy into a Set.
    final Set<TupleQueryResultFormat> values = new LinkedHashSet<TupleQueryResultFormat>(
            TupleQueryResultFormat.values());
    
    final TupleQueryResultParserRegistry registry = TupleQueryResultParserRegistry
            .getInstance();
    
    final Iterator<TupleQueryResultFormat> itr = values.iterator();

    while (itr.hasNext()) {

        final TupleQueryResultFormat format = itr.next();

        if (registry.get(format) == null) {

            /*
             * Remove any format for which there is no registered parser.
             * 
             * Note: For example, the JSON parser does not exist for openrdf
             * 2.6.3.
             */
            
            itr.remove();

        }

    }
    
    final List<String> list2 = AcceptHeaderFactory.getAcceptParams(values,
            TupleQueryResultFormat.BINARY);

    return toString(list2);
    
}