Package org.aksw.qa.commons.sparql

Class ThreadedSPARQL

java.lang.Object

org.aksw.qa.commons.sparql.SPARQL

org.aksw.qa.commons.sparql.ThreadedSPARQL

public class ThreadedSPARQL
extends SPARQL

Fire a sparql query against an endpoint

SPARQL.sparql(String) will block, if server doesn't respond. Here, you can set a maximum time limit.

This is achieved by wrapping underlying SPARQL in a Thread, which then has a maximum execution time.

Author:

jhuth

Field Summary

Fields

Modifier and Type	Field	Description
(package private) ExecutorService	executor
private org.slf4j.Logger	log
private int	timeoutInSeconds

Fields inherited from class org.aksw.qa.commons.sparql.SPARQL

qef

Constructor Summary

Constructors

Constructor	Description
ThreadedSPARQL()	#ENDPOINT_DBPEDIA_ORG as endpoint used.
ThreadedSPARQL(int timeoutInSeconds, String endpoint)
ThreadedSPARQL(String endpoint)	Default timeout : 10 seconds

Method Summary

Modifier and Type	Method	Description
void	destroy()	Call this to close the underlying thread pool.
int	getTimeoutInSeconds()
static void	main(String[] args)
void	setTimeoutInSeconds(int timeoutInSeconds)
Set<org.apache.jena.rdf.model.RDFNode>	sparql(String query)	Fire a sparql query against endpoint defined in constructor.

Methods inherited from class java.lang.Object

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

Methods inherited from class org.aksw.qa.commons.sparql.SPARQL

extractAnswerStrings, getCacheTimeToLive, isValidSparqlQuery, setCacheTimeToLive

Field Detail

timeoutInSeconds

private int timeoutInSeconds

log

private final org.slf4j.Logger log

executor

ExecutorService executor

Constructor Detail

ThreadedSPARQL

public ThreadedSPARQL()

#ENDPOINT_DBPEDIA_ORG as endpoint used.

Default timeout : 10 seconds

ThreadedSPARQL

public ThreadedSPARQL(String endpoint)

Default timeout : 10 seconds

ThreadedSPARQL

public ThreadedSPARQL(int timeoutInSeconds,
                      String endpoint)

Parameters:

timeoutInSeconds - - set a maximum time limit for the execution of one query. Only set if >0 otherwise ignored (default=10s)

endpoint - - A sparql endpoint, e.g. SPARQLEndpoints.DBPEDIA_ORG

Method Detail

sparql

public Set<org.apache.jena.rdf.model.RDFNode> sparql(String query)
                                              throws ExecutionException

Fire a sparql query against endpoint defined in constructor.

This will break operation after timeoutInSeconds has been reached. in this case, null is returned.

For string representation of answers, see SPARQL.extractAnswerStrings(Set)

Overrides:

sparql in class SPARQL

Parameters:

query - - a sparql query

Returns:

Throws:

ExecutionException

getTimeoutInSeconds

public int getTimeoutInSeconds()

Returns:

- the time after a query times out.

setTimeoutInSeconds

public void setTimeoutInSeconds(int timeoutInSeconds)

Parameters:

timeoutInSeconds - - the time after a query times out.

destroy

public void destroy()

Call this to close the underlying thread pool.

main

public static void main(String[] args)
                 throws InterruptedException,
                        ExecutionException

Throws:

InterruptedException

ExecutionException