Java Code Examples for org.apache.jena.query.Dataset#begin()

/**
 * Loads the test TDB used in this class with a bounch of RDF data.
 */
@BeforeClass
public static void initData ()
{
	rdfMgr.open ( TDB_PATH );
	Dataset ds = rdfMgr.getDataSet ();
	Model m = ds.getDefaultModel ();
	ds.begin ( ReadWrite.WRITE );
	try 
	{
		//if ( m.size () > 0 ) return;
		m.read ( IOUtils.openResourceReader ( "test_data.ttl" ), null, "TURTLE" );
		ds.commit ();
	}
	catch ( Exception ex ) {
		ds.abort ();
		throw new RuntimeException ( "Test error: " + ex.getMessage (), ex );
	}
	finally { 
		ds.end ();
	}
}
 

/**
 * Take an existing {@link CypherEntity} and adds the properties that can be mapped from the underlining TDB by means 
 * of a property query, like {@link CyNodeLoadingHandler#getNodePropsSparql()}, or 
 * {@link CyRelationLoadingHandler#getRelationPropsSparql()}.
 * 
 * It doesn't do anything if the query is null.
 * 
 */
protected void addCypherProps ( CypherEntity cyEnt, String propsSparql )
{
	ensureOpen ();		
	Dataset dataSet = this.getDataSet ();
	
	QuerySolutionMap params = new QuerySolutionMap ();
	params.add ( "iri", dataSet.getUnionModel().getResource ( cyEnt.getIri () ) );

	// It may be omitted, if you don't have any property except the IRI.
	if ( propsSparql == null ) return;
	
	Query qry = SparqlUtils.getCachedQuery ( propsSparql );
	Function<String, String> propIdConverter = this.getCyPropertyIdConverter ();
	
	boolean wasInTnx = dataSet.isInTransaction ();
	if ( !wasInTnx ) dataSet.begin ( ReadWrite.READ );
	try
	{
		QueryExecution qx = QueryExecutionFactory.create ( qry, dataSet, params );
		qx.execSelect ().forEachRemaining ( row ->
		{
			String propName = this.getCypherId ( row.get ( "name" ), propIdConverter );
			if ( propName == null ) throw new IllegalArgumentException ( 
				"Null property name for " + cyEnt.getIri () 
			);
			
			String propValue = JENAUTILS.literal2Value ( row.getLiteral ( "value" ) ).get ();
			cyEnt.addPropValue ( propName, propValue );
		});
	}
	finally {
		if ( !wasInTnx && dataSet.isInTransaction () ) dataSet.end ();
	}
}
 

/**
 * Given a path to an RDF/XML or TTL file and a RDF language, load the file as the default model
 * of a TDB dataset backed by a directory to improve processing time. Return the new dataset.
 *
 * <p>WARNING - this creates a directory at given tdbDir location!
 *
 * @param inputPath input path of RDF/XML or TTL file
 * @param tdbDir location to put TDB mappings
 * @return Dataset instantiated with triples
 * @throws JenaException if TDB directory can't be written to
 */
public static Dataset loadToTDBDataset(String inputPath, String tdbDir) throws JenaException {
  Dataset dataset;
  if (new File(tdbDir).isDirectory()) {
    dataset = TDBFactory.createDataset(tdbDir);
    if (!dataset.isEmpty()) {
      return dataset;
    }
  }
  dataset = TDBFactory.createDataset(tdbDir);
  logger.debug(String.format("Parsing input '%s' to dataset", inputPath));
  // Track parsing time
  long start = System.nanoTime();
  Model m;
  dataset.begin(ReadWrite.WRITE);
  try {
    m = dataset.getDefaultModel();
    FileManager.get().readModel(m, inputPath);
    dataset.commit();
  } catch (JenaException e) {
    dataset.abort();
    dataset.end();
    dataset.close();
    throw new JenaException(String.format(syntaxError, inputPath));
  } finally {
    dataset.end();
  }
  long time = (System.nanoTime() - start) / 1000000000;
  logger.debug(String.format("Parsing complete - took %s seconds", String.valueOf(time)));
  return dataset;
}
 

public static void main(String... argv)
{
    String directory = "MyDatabases/DB1" ;
    Dataset dataset = TDBFactory.createDataset(directory) ;

    // Start WRITE transaction. 
    //   It's possible to read from the datet inside the write transaction.

    //   An application can have other Datasets, in the same JVM, 
    //   tied to the same TDB database performing read
    //   transactions concurrently. If another write transaction
    //   starts, the call of dataset.begin(WRITE) blocks until
    //   existing writer finishes.
    
    dataset.begin(ReadWrite.WRITE) ;
    try
    {
        GraphStore graphStore = GraphStoreFactory.create(dataset) ;
        // Do a SPARQL Update.
        String sparqlUpdateString = StrUtils.strjoinNL(
             "PREFIX . <http://example/>",
             "INSERT { :s :p ?now } WHERE { BIND(now() AS ?now) }"
             ) ;

        execUpdate(sparqlUpdateString, graphStore) ;
        dataset.commit() ;
        // Or call .abort()
        
    } finally
    {
        // Notify the end of the transaction.
        // The transaction was finished at the point .commit or .abort was called.
        // .end will force an abort() if no previous call to .commit() or .abort()
        // has occurred, so .end() help manage track the state of the transaction.
        // .end() can be called multiple times for the same .begin(WRITE)
        dataset.end() ;
    }
}
 

public static void main(String... argv)
{
    String directory = "MyDatabases/DB1" ;
    Dataset dataset = TDBFactory.createDataset(directory) ;

    // Start READ transaction. 
    //   No updates or changes to the dataset are possible while this
    //   dataset is used for a read transaction.
    //   An application can have other Datasets, in the same JVM, 
    //   tied to the same TDB database performing read or write
    //   transactions concurrently.
    
    dataset.begin(ReadWrite.READ) ;
    try
    {
        // Do some queries
        String sparqlQueryString1 = "SELECT (count(*) AS ?count) { ?s ?p ?o }" ;
        execQuery(sparqlQueryString1, dataset) ;
        
        String sparqlQueryString2 = "SELECT * { ?s ?p ?o }" ;
        execQuery(sparqlQueryString2, dataset) ;
        
        // Can also call dataset.abort() or dataset.commit() here 
    } finally
    {
        // Notify the end of the READ transaction.
        // Any use of dataset.abort() or dataset.commit() or dataset.end()
        // .end() can be called multiple times for the same .begin(READ)
        dataset.end() ;
    }
}