class EasyRdf_Sparql_Client in Zircon Profile 8

Class for making SPARQL queries using the SPARQL 1.1 Protocol

@package EasyRdf @copyright Copyright (c) 2009-2013 Nicholas J Humfrey @license http://www.opensource.org/licenses/bsd-license.php

Hierarchy

• class \EasyRdf_Sparql_Client

File

vendor/easyrdf/easyrdf/lib/EasyRdf/Sparql/Client.php, line 45

class EasyRdf_Sparql_Client {

  /** The query/read address of the SPARQL Endpoint */
  private $queryUri = null;
  private $queryUri_has_params = false;

  /** The update/write address of the SPARQL Endpoint */
  private $updateUri = null;

  /** Create a new SPARQL endpoint client
   *
   * If the query and update endpoints are the same, then you
   * only need to give a single URI.
   *
   * @param string $queryUri The address of the SPARQL Query Endpoint
   * @param string $updateUri Optional address of the SPARQL Update Endpoint
   */
  public function __construct($queryUri, $updateUri = null) {
    $this->queryUri = $queryUri;
    if (strlen(parse_url($queryUri, PHP_URL_QUERY)) > 0) {
      $this->queryUri_has_params = true;
    }
    else {
      $this->queryUri_has_params = false;
    }
    if ($updateUri) {
      $this->updateUri = $updateUri;
    }
    else {
      $this->updateUri = $queryUri;
    }
  }

  /** Get the URI of the SPARQL query endpoint
   *
   * @return string The query URI of the SPARQL endpoint
   */
  public function getQueryUri() {
    return $this->queryUri;
  }

  /** Get the URI of the SPARQL update endpoint
   *
   * @return string The query URI of the SPARQL endpoint
   */
  public function getUpdateUri() {
    return $this->updateUri;
  }

  /**
   * @depredated
   * @ignore
   */
  public function getUri() {
    return $this->queryUri;
  }

  /** Make a query to the SPARQL endpoint
   *
   * SELECT and ASK queries will return an object of type
   * EasyRdf_Sparql_Result.
   *
   * CONSTRUCT and DESCRIBE queries will return an object
   * of type EasyRdf_Graph.
   *
   * @param string $query The query string to be executed
   * @return object EasyRdf_Sparql_Result|EasyRdf_Graph Result of the query.
   */
  public function query($query) {
    return $this
      ->request('query', $query);
  }

  /** Count the number of triples in a SPARQL 1.1 endpoint
   *
   * Performs a SELECT query to estriblish the total number of triples.
   *
   * Counts total number of triples by default but a conditional triple pattern
   * can be given to count of a subset of all triples.
   *
   * @param string $condition Triple-pattern condition for the count query
   * @return integer The number of triples
   */
  public function countTriples($condition = '?s ?p ?o') {

    // SELECT (COUNT(*) AS ?count)
    // WHERE {
    //   {?s ?p ?o}
    //   UNION
    //   {GRAPH ?g {?s ?p ?o}}
    // }
    $result = $this
      ->query('SELECT (COUNT(*) AS ?count) {' . $condition . '}');
    return $result[0]->count
      ->getValue();
  }

  /** Get a list of named graphs from a SPARQL 1.1 endpoint
   *
   * Performs a SELECT query to get a list of the named graphs
   *
   * @param string $limit Optional limit to the number of results
   * @return array Array of EasyRdf_Resource objects for each named graph
   */
  public function listNamedGraphs($limit = null) {
    $query = "SELECT DISTINCT ?g WHERE {GRAPH ?g {?s ?p ?o}}";
    if (!is_null($limit)) {
      $query .= " LIMIT " . (int) $limit;
    }
    $result = $this
      ->query($query);

    // Convert the result object into an array of resources
    $graphs = array();
    foreach ($result as $row) {
      array_push($graphs, $row->g);
    }
    return $graphs;
  }

  /** Make an update request to the SPARQL endpoint
   *
   * Successful responses will return the HTTP response object
   *
   * Unsuccessful responses will throw an exception
   *
   * @param string $query The update query string to be executed
   * @return object EasyRdf_Http_Response HTTP response
   */
  public function update($query) {
    return $this
      ->request('update', $query);
  }
  public function insert($data, $graphUri = null) {

    #$this->updateData('INSET',
    $query = 'INSERT DATA {';
    if ($graphUri) {
      $query .= "GRAPH <{$graphUri}> {";
    }
    $query .= $this
      ->convertToTriples($data);
    if ($graphUri) {
      $query .= "}";
    }
    $query .= '}';
    return $this
      ->update($query);
  }
  protected function updateData($operation, $data, $graphUri = null) {
    $query = "{$operation} DATA {";
    if ($graphUri) {
      $query .= "GRAPH <{$graphUri}> {";
    }
    $query .= $this
      ->convertToTriples($data);
    if ($graphUri) {
      $query .= "}";
    }
    $query .= '}';
    return $this
      ->update($query);
  }
  public function clear($graphUri, $silent = false) {
    $query = "CLEAR";
    if ($silent) {
      $query .= " SILENT";
    }
    if (preg_match('/^all|named|default$/i', $graphUri)) {
      $query .= " {$graphUri}";
    }
    else {
      $query .= " GRAPH <{$graphUri}>";
    }
    return $this
      ->update($query);
  }

  /*
   * Internal function to make an HTTP request to SPARQL endpoint
   *
   * @ignore
   */
  protected function request($type, $query) {

    // Check for undefined prefixes
    $prefixes = '';
    foreach (EasyRdf_Namespace::namespaces() as $prefix => $uri) {
      if (strpos($query, "{$prefix}:") !== false and strpos($query, "PREFIX {$prefix}:") === false) {
        $prefixes .= "PREFIX {$prefix}: <{$uri}>\n";
      }
    }
    $client = EasyRdf_Http::getDefaultHttpClient();
    $client
      ->resetParameters();

    // Tell the server which response formats we can parse
    $accept = EasyRdf_Format::getHttpAcceptHeader(array(
      'application/sparql-results+json' => 1.0,
      'application/sparql-results+xml' => 0.8,
    ));
    $client
      ->setHeaders('Accept', $accept);
    if ($type == 'update') {
      $client
        ->setMethod('POST');
      $client
        ->setUri($this->updateUri);
      $client
        ->setRawData($prefixes . $query);
      $client
        ->setHeaders('Content-Type', 'application/sparql-update');
    }
    elseif ($type == 'query') {

      // Use GET if the query is less than 2kB
      // 2046 = 2kB minus 1 for '?' and 1 for NULL-terminated string on server
      $encodedQuery = 'query=' . urlencode($prefixes . $query);
      if (strlen($encodedQuery) + strlen($this->queryUri) <= 2046) {
        $delimiter = $this->queryUri_has_params ? '&' : '?';
        $client
          ->setMethod('GET');
        $client
          ->setUri($this->queryUri . $delimiter . $encodedQuery);
      }
      else {

        // Fall back to POST instead (which is un-cacheable)
        $client
          ->setMethod('POST');
        $client
          ->setUri($this->queryUri);
        $client
          ->setRawData($encodedQuery);
        $client
          ->setHeaders('Content-Type', 'application/x-www-form-urlencoded');
      }
    }
    $response = $client
      ->request();
    if ($response
      ->getStatus() == 204) {

      // No content
      return $response;
    }
    elseif ($response
      ->isSuccessful()) {
      list($type, $params) = EasyRdf_Utils::parseMimeType($response
        ->getHeader('Content-Type'));
      if (strpos($type, 'application/sparql-results') === 0) {
        return new EasyRdf_Sparql_Result($response
          ->getBody(), $type);
      }
      else {
        return new EasyRdf_Graph($this->queryUri, $response
          ->getBody(), $type);
      }
    }
    else {
      throw new EasyRdf_Exception("HTTP request for SPARQL query failed: " . $response
        ->getBody());
    }
  }
  protected function convertToTriples($data) {
    if (is_string($data)) {
      return $data;
    }
    elseif (is_object($data) and $data instanceof EasyRdf_Graph) {

      # FIXME: insert Turtle when there is a way of seperateing out the prefixes
      return $data
        ->serialise('ntriples');
    }
    else {
      throw new EasyRdf_Exception("Don't know how to convert to triples for SPARQL query: " . $response
        ->getBody());
    }
  }

}

Members

Name	Modifiers	Type	Description	Overrides
EasyRdf_Sparql_Client::$queryUri	private	property	The query/read address of the SPARQL Endpoint
EasyRdf_Sparql_Client::$queryUri_has_params	private	property
EasyRdf_Sparql_Client::$updateUri	private	property	The update/write address of the SPARQL Endpoint
EasyRdf_Sparql_Client::clear	public	function
EasyRdf_Sparql_Client::convertToTriples	protected	function
EasyRdf_Sparql_Client::countTriples	public	function	Count the number of triples in a SPARQL 1.1 endpoint
EasyRdf_Sparql_Client::getQueryUri	public	function	Get the URI of the SPARQL query endpoint
EasyRdf_Sparql_Client::getUpdateUri	public	function	Get the URI of the SPARQL update endpoint
EasyRdf_Sparql_Client::getUri	public	function	@depredated @ignore
EasyRdf_Sparql_Client::insert	public	function
EasyRdf_Sparql_Client::listNamedGraphs	public	function	Get a list of named graphs from a SPARQL 1.1 endpoint
EasyRdf_Sparql_Client::query	public	function	Make a query to the SPARQL endpoint
EasyRdf_Sparql_Client::request	protected	function
EasyRdf_Sparql_Client::update	public	function	Make an update request to the SPARQL endpoint
EasyRdf_Sparql_Client::updateData	protected	function
EasyRdf_Sparql_Client::__construct	public	function	Create a new SPARQL endpoint client