/// <summary> /// Processes a SPARQL Query against the Knowledge Base passing the results to the RDF or Results handler as appropriate /// </summary> /// <param name="rdfHandler">RDF Handler</param> /// <param name="resultsHandler">Results Handler</param> /// <param name="sparqlQuery">SPARQL Query</param> /// <param name="callback">Callback to invoke once handling of results has completed</param> /// <param name="state">State to pass to the callback</param> public void Query(IRdfHandler rdfHandler, ISparqlResultsHandler resultsHandler, String sparqlQuery, QueryCallback callback, Object state) { SparqlQueryParser parser = new SparqlQueryParser(); SparqlQuery q = parser.ParseFromString(sparqlQuery); SparqlRemoteEndpoint endpoint = new SparqlRemoteEndpoint(UriFactory.Create(this._sparqlUri)); switch (q.QueryType) { case SparqlQueryType.Ask: case SparqlQueryType.Select: case SparqlQueryType.SelectAll: case SparqlQueryType.SelectAllDistinct: case SparqlQueryType.SelectAllReduced: case SparqlQueryType.SelectDistinct: case SparqlQueryType.SelectReduced: endpoint.QueryWithResultSet(sparqlQuery, (rs, _) => { resultsHandler.Apply(rs); callback(rdfHandler, resultsHandler, state); }, state); break; case SparqlQueryType.Construct: case SparqlQueryType.Describe: case SparqlQueryType.DescribeAll: endpoint.QueryWithResultGraph(sparqlQuery, (g, _) => { rdfHandler.Apply(g); callback(rdfHandler, resultsHandler, state); }, state); break; default: throw new RdfQueryException("Cannot execute unknown query types against Pellet Server"); } }
/// <summary> /// Processes a SPARQL Query sending the results to a RDF/SPARQL Results handler as appropriate /// </summary> /// <param name="rdfHandler">RDF Handler</param> /// <param name="resultsHandler">Results Handler</param> /// <param name="query">SPARQL Query</param> public void ProcessQuery(IRdfHandler rdfHandler, ISparqlResultsHandler resultsHandler, SparqlQuery query) { //Do Handler null checks before evaluating the query if (query == null) { throw new ArgumentNullException("query", "Cannot evaluate a null query"); } if (rdfHandler == null && (query.QueryType == SparqlQueryType.Construct || query.QueryType == SparqlQueryType.Describe || query.QueryType == SparqlQueryType.DescribeAll)) { throw new ArgumentNullException("rdfHandler", "Cannot use a null RDF Handler when the Query is a CONSTRUCT/DESCRIBE"); } if (resultsHandler == null && (query.QueryType == SparqlQueryType.Ask || SparqlSpecsHelper.IsSelectQuery(query.QueryType))) { throw new ArgumentNullException("resultsHandler", "Cannot use a null resultsHandler when the Query is an ASK/SELECT"); } //Handle the Thread Safety of the Query Evaluation #if !NO_RWLOCK ReaderWriterLockSlim currLock = (this._dataset is IThreadSafeDataset) ? ((IThreadSafeDataset)this._dataset).Lock : this._lock; try { currLock.EnterReadLock(); #endif //Reset Query Timers query.QueryExecutionTime = null; bool datasetOk = false, defGraphOk = false; try { //Set up the Default and Active Graphs if (query.DefaultGraphs.Any()) { //Call HasGraph() on each Default Graph but ignore the results, we just do this //in case a dataset has any kind of load on demand behaviour foreach (Uri defGraphUri in query.DefaultGraphs) { this._dataset.HasGraph(defGraphUri); } this._dataset.SetDefaultGraph(query.DefaultGraphs); defGraphOk = true; } else if (query.NamedGraphs.Any()) { //No FROM Clauses but one/more FROM NAMED means the Default Graph is the empty graph this._dataset.SetDefaultGraph(Enumerable.Empty <Uri>()); } this._dataset.SetActiveGraph(this._dataset.DefaultGraphUris); datasetOk = true; //Convert to Algebra and execute the Query SparqlEvaluationContext context = this.GetContext(query); BaseMultiset result; try { context.StartExecution(); ISparqlAlgebra algebra = query.ToAlgebra(); result = context.Evaluate(algebra); context.EndExecution(); query.QueryExecutionTime = new TimeSpan(context.QueryTimeTicks); } catch (RdfQueryException) { context.EndExecution(); query.QueryExecutionTime = new TimeSpan(context.QueryTimeTicks); throw; } catch { context.EndExecution(); query.QueryExecutionTime = new TimeSpan(context.QueryTimeTicks); throw; } //Return the Results switch (query.QueryType) { case SparqlQueryType.Ask: case SparqlQueryType.Select: case SparqlQueryType.SelectAll: case SparqlQueryType.SelectAllDistinct: case SparqlQueryType.SelectAllReduced: case SparqlQueryType.SelectDistinct: case SparqlQueryType.SelectReduced: //For SELECT and ASK can populate a Result Set directly from the Evaluation Context //return new SparqlResultSet(context); resultsHandler.Apply(context); break; case SparqlQueryType.Construct: //Create a new Empty Graph for the Results try { rdfHandler.StartRdf(); foreach (String prefix in query.NamespaceMap.Prefixes) { if (!rdfHandler.HandleNamespace(prefix, query.NamespaceMap.GetNamespaceUri(prefix))) { ParserHelper.Stop(); } } //Construct the Triples for each Solution foreach (ISet s in context.OutputMultiset.Sets) { //List<Triple> constructedTriples = new List<Triple>(); try { ConstructContext constructContext = new ConstructContext(rdfHandler, s, false); foreach (IConstructTriplePattern p in query.ConstructTemplate.TriplePatterns.OfType <IConstructTriplePattern>()) { try { if (!rdfHandler.HandleTriple(p.Construct(constructContext))) { ParserHelper.Stop(); } //constructedTriples.Add(((IConstructTriplePattern)p).Construct(constructContext)); } catch (RdfQueryException) { //If we get an error here then we could not construct a specific triple //so we continue anyway } } } catch (RdfQueryException) { //If we get an error here this means we couldn't construct for this solution so the //entire solution is discarded continue; } //h.Assert(constructedTriples); } rdfHandler.EndRdf(true); } catch (RdfParsingTerminatedException) { rdfHandler.EndRdf(true); } catch { rdfHandler.EndRdf(false); throw; } break; case SparqlQueryType.Describe: case SparqlQueryType.DescribeAll: //For DESCRIBE we retrieve the Describe algorithm and apply it ISparqlDescribe describer = query.Describer; describer.Describe(rdfHandler, context); break; default: throw new RdfQueryException("Unknown query types cannot be processed by Leviathan"); } } finally { if (defGraphOk) { this._dataset.ResetDefaultGraph(); } if (datasetOk) { this._dataset.ResetActiveGraph(); } } #if !NO_RWLOCK } finally { currLock.ExitReadLock(); } #endif }
/// <summary> /// Processes a SPARQL Query against the Knowledge Base passing the results to the RDF or Results handler as appropriate /// </summary> /// <param name="rdfHandler">RDF Handler</param> /// <param name="resultsHandler">Results Handler</param> /// <param name="sparqlQuery">SPARQL Query</param> /// <param name="callback">Callback to invoke once handling of results has completed</param> /// <param name="state">State to pass to the callback</param> public void Query(IRdfHandler rdfHandler, ISparqlResultsHandler resultsHandler, String sparqlQuery, QueryCallback callback, Object state) { SparqlQueryParser parser = new SparqlQueryParser(); SparqlQuery q = parser.ParseFromString(sparqlQuery); SparqlRemoteEndpoint endpoint = new SparqlRemoteEndpoint(UriFactory.Create(this._sparqlUri)); switch (q.QueryType) { case SparqlQueryType.Ask: case SparqlQueryType.Select: case SparqlQueryType.SelectAll: case SparqlQueryType.SelectAllDistinct: case SparqlQueryType.SelectAllReduced: case SparqlQueryType.SelectDistinct: case SparqlQueryType.SelectReduced: endpoint.QueryWithResultSet(sparqlQuery, (rs, _) => { resultsHandler.Apply(rs); callback(rdfHandler, resultsHandler, state); }, state); break; case SparqlQueryType.Construct: case SparqlQueryType.Describe: case SparqlQueryType.DescribeAll: endpoint.QueryWithResultGraph(sparqlQuery, (g, _) => { rdfHandler.Apply(g); callback(rdfHandler, resultsHandler, state); }, state); break; default: throw new RdfQueryException("Cannot execute unknown query types against Pellet Server"); } }