org.dice_research.squirrel.fetcher.sparql

Class SparqlBasedFetcher

java.lang.Object

org.dice_research.squirrel.fetcher.sparql.SparqlBasedFetcher

All Implemented Interfaces:

Closeable, AutoCloseable, Fetcher

public class SparqlBasedFetcher
extends Object
implements Fetcher

A simple Fetcher for SPARQL that tries to get triples from a SPARQL endpoint using the query "SELECT ?s ?p ?o\r\nWHERE {\r\nGRAPH ?g {\r\n?s ?p ?o\r\n}} ".

Author:

Michael Röder (michael.roeder@uni-paderborn.de)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	SparqlBasedFetcher.SelectedTriplesIterator

Field Summary

Fields

Modifier and Type	Field and Description
protected File	dataDirectory
private static org.slf4j.Logger	LOGGER
private static int	MINIMUM_DELAY The default minimum delay that the system will have between sending two queries.
protected int	minimumDelay
private static String	SELECT_ALL_TRIPLES_QUERY

Constructor Summary

Constructors

Constructor and Description
SparqlBasedFetcher()

Method Summary

Modifier and Type	Method and Description
void	close()
File	fetch(org.dice_research.squirrel.data.uri.CrawleableUri uri, Delayer delayer) Fetches a stream of data from the given URI by following the delay implemented by the given Delayer, stores it and returns a File object pointing to the stored data.
protected org.aksw.jena_sparql_api.core.QueryExecutionFactory	initQueryExecution(String uri, Delayer delayer)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.dice_research.squirrel.fetcher.Fetcher

fetch

Field Detail

LOGGER

private static final org.slf4j.Logger LOGGER

MINIMUM_DELAY

private static final int MINIMUM_DELAY

The default minimum delay that the system will have between sending two queries.

See Also:

Constant Field Values

SELECT_ALL_TRIPLES_QUERY

private static final String SELECT_ALL_TRIPLES_QUERY

See Also:

Constant Field Values

minimumDelay

protected int minimumDelay

dataDirectory

protected File dataDirectory

Constructor Detail

SparqlBasedFetcher

public SparqlBasedFetcher()

Method Detail

fetch

public File fetch(org.dice_research.squirrel.data.uri.CrawleableUri uri,
                  Delayer delayer)

Description copied from interface: Fetcher

Fetches a stream of data from the given URI by following the delay implemented by the given Delayer, stores it and returns a File object pointing to the stored data. If an error occurs, null is returned.

Specified by:

fetch in interface Fetcher

Parameters:

uri - The URI from which data should be fetched.

Returns:

A File object pointing to the downloaded data or null if an error occurred.

initQueryExecution

protected org.aksw.jena_sparql_api.core.QueryExecutionFactory initQueryExecution(String uri,
                                                                                 Delayer delayer)
                                                                          throws ClassNotFoundException,
                                                                                 SQLException

Throws:

ClassNotFoundException

SQLException

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException