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<?php
namespace SMW\SPARQLStore\RepositoryConnectors;
use SMW\SPARQLStore\Exception\BadHttpEndpointResponseException;
use SMW\SPARQLStore\QueryEngine\RepositoryResult;
use SMW\SPARQLStore\QueryEngine\XmlResponseParser;
use SMWTurtleSerializer as TurtleSerializer;
/**
* Specific modifications of the SPARQL database implementation for 4Store.
*
* @license GNU GPL v2+
* @since 1.6
*
* @author Markus Krötzsch
*/
class FourstoreRepositoryConnector extends GenericRepositoryConnector {
/**
* Execute a SPARQL query and return an RepositoryResult object
* that contains the results. Compared to GenericHttpDatabaseConnector::doQuery(),
* this also supports the parameter "restricted=1" which 4Store provides
* to enforce strict resource bounds on query answering. The method also
* checks if these bounds have been met, and records this in the query
* result.
*
* @note The restricted option in 4Store mainly enforces the given soft
* limit more strictly. To disable/configure it, simply change the soft
* limit settings of your 4Store server.
*
* @param $sparql string with the complete SPARQL query (SELECT or ASK)
* @return RepositoryResult
*/
public function doQuery( $sparql ) {
if ( $this->repositoryClient->getQueryEndpoint() === '' ) {
throw new BadHttpEndpointResponseException( BadHttpEndpointResponseException::ERROR_NOSERVICE, $sparql, 'not specified' );
}
$this->httpRequest->setOption( CURLOPT_URL, $this->repositoryClient->getQueryEndpoint() );
$this->httpRequest->setOption( CURLOPT_HTTPHEADER, ['Accept: application/sparql-results+xml,application/xml;q=0.8' ]);
$this->httpRequest->setOption( CURLOPT_POST, true );
$defaultGraph = $this->repositoryClient->getDefaultGraph();
$parameterString = "query=" . urlencode( $sparql ) . "&restricted=1" .
( ( $defaultGraph !== '' )? '&default-graph-uri=' . urlencode( $defaultGraph ) : '' );
$this->httpRequest->setOption( CURLOPT_POSTFIELDS, $parameterString );
$httpResponse = $this->httpRequest->execute();
if ( $this->httpRequest->getLastErrorCode() == 0 ) {
$xmlResponseParser = new XmlResponseParser();
$result = $xmlResponseParser->parse( $httpResponse );
} else {
$this->mapHttpRequestError( $this->repositoryClient->getQueryEndpoint(), $sparql );
$result = new RepositoryResult();
$result->setErrorCode( RepositoryResult::ERROR_UNREACHABLE );
}
foreach ( $result->getComments() as $comment ) {
if ( strpos( $comment, 'warning: hit complexity limit' ) === 0 ||
strpos( $comment, 'some results have been dropped' ) === 0 ) {
$result->setErrorCode( RepositoryResult::ERROR_INCOMPLETE );
} //else debug_zval_dump($comment);
}
return $result;
}
/**
* Complex SPARQL Update delete operations are not supported in 4Store
* as of v1.1.3, hence this implementation uses a less efficient method
* for accomplishing this.
*
* @param $propertyName string Turtle name of marking property
* @param $objectName string Turtle name of marking object/value
* @param $extraNamespaces array (associative) of namespaceId => namespaceUri
* @return boolean stating whether the operations succeeded
*/
public function deleteContentByValue( $propertyName, $objectName, $extraNamespaces = [] ) {
$affectedObjects = $this->select( '*', "?s $propertyName $objectName", [], $extraNamespaces );
$success = ( $affectedObjects->getErrorCode() == RepositoryResult::ERROR_NOERROR );
foreach ( $affectedObjects as $expElements ) {
if ( count( $expElements ) > 0 ) {
$turtleName = TurtleSerializer::getTurtleNameForExpElement( reset( $expElements ) );
$success = $this->delete( "$turtleName ?p ?o", "$turtleName ?p ?o", $extraNamespaces ) && $success;
}
}
return $success;
}
/**
* Execute a HTTP-based SPARQL POST request according to
* http://www.w3.org/2009/sparql/docs/http-rdf-update/.
* The method throws exceptions based on
* GenericHttpDatabaseConnector::mapHttpRequestError(). If errors occur and this
* method does not throw anything, then an empty result with an error
* code is returned.
*
* This method is specific to 4Store since it uses POST parameters that
* are not given in the specification.
*
* @param $payload string Turtle serialization of data to send
*
* @return boolean
*/
public function doHttpPost( $payload ) {
if ( $this->repositoryClient->getDataEndpoint() === '' ) {
throw new BadHttpEndpointResponseException( BadHttpEndpointResponseException::ERROR_NOSERVICE, "SPARQL POST with data: $payload", 'not specified' );
}
$this->httpRequest->setOption( CURLOPT_URL, $this->repositoryClient->getDataEndpoint() );
$this->httpRequest->setOption( CURLOPT_POST, true );
$defaultGraph = $this->repositoryClient->getDefaultGraph();
$parameterString = "data=" . urlencode( $payload ) . '&graph=' .
( ( $defaultGraph !== '' )? urlencode( $defaultGraph ) : 'default' ) .
'&mime-type=application/x-turtle';
$this->httpRequest->setOption( CURLOPT_POSTFIELDS, $parameterString );
$this->httpRequest->execute();
if ( $this->httpRequest->getLastErrorCode() == 0 ) {
return true;
}
$this->mapHttpRequestError( $this->repositoryClient->getDataEndpoint(), $payload );
return false;
}
/**
* @see GenericHttpDatabaseConnector::doUpdate
*
* @note 4store 1.1.4 breaks on update if charset is set in the Content-Type header
*
* @since 2.0
*/
public function doUpdate( $sparql ) {
if ( $this->repositoryClient->getUpdateEndpoint() === '' ) {
throw new BadHttpEndpointResponseException( BadHttpEndpointResponseException::ERROR_NOSERVICE, $sparql, 'not specified' );
}
$this->httpRequest->setOption( CURLOPT_URL, $this->repositoryClient->getUpdateEndpoint() );
$this->httpRequest->setOption( CURLOPT_POST, true );
$parameterString = "update=" . urlencode( $sparql );
$this->httpRequest->setOption( CURLOPT_POSTFIELDS, $parameterString );
$this->httpRequest->setOption( CURLOPT_HTTPHEADER, ['Content-Type: application/x-www-form-urlencoded' ] );
$this->httpRequest->execute();
if ( $this->httpRequest->getLastErrorCode() == 0 ) {
return true;
}
$this->mapHttpRequestError( $this->repositoryClient->getUpdateEndpoint(), $sparql );
return false;
}
}
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