view sites/all/modules/sparql/sparql.module @ 4:ce11bbd8f642

added modules

<?php
/*
 * @file
 * API function for running queries on external SPARQL endpoints.
 */

define('SPARQL_ENDPOINT', 'endpoint');

/**
 * Implements hook_help().
 */
function sparql_help($path, $arg = NULL) {
  switch ($path) {
    case 'admin/settings/sparql':
      return '<p>' . t('The sparql module provides an interface for other modules to perform sparql queries') . '</p>'; // TODO
  }
}

/**
 * Executes a SPARQL query.
 *
 * @param $query
 *   The SPARQL query to execute.
 * @param $endpoint
 *   An endpoint object, as returned by SPARQL Registry.
 * @return
 *   The SPARQL results.
 */
function sparql_request($query, $endpoint) {
  $rows = _sparql_request($query, $endpoint);
  return $rows;
}

function sparql_get_store($name, $type = 'store') {
  $db = $GLOBALS['databases']['default']['default'];
  $name = "sparql_store_$name";

  $config = array(
    /* db */
    'db_host' => $db['host'],
    'db_name' => $db['database'],
    'db_user' => $db['username'],
    'db_pwd' => $db['password'],
    /* store */
    'store_name' => $name,

    /* endpoint */
    'endpoint_features' => array(
      'select', 'construct', 'ask', 'describe',
      'load', 'insert', 'delete',
      'dump' /* dump is a special command for streaming SPOG export */
    ),
    'endpoint_timeout' => 60, /* not implemented in ARC2 preview */
    'endpoint_read_key' => '', /* optional */
    'endpoint_write_key' => 'somekey', /* optional */
    'endpoint_max_limit' => 500, /* optional */
  );

  /* instantiation */
  if ($type == SPARQL_ENDPOINT) {
    $store = ARC2::getStoreEndpoint($config);
  }
  else {
    $store = ARC2::getStore($config);
  }
  if (!$store->isSetUp()) {
    $store->setUp();
  }
  return $store;
}

/**
 * Runs a query against an endpoint.
 *
 * @param $query
 *   The SPARQL query to execute.
 * @param $endpoint
 *   The endpoint to try the query against.
 * @options
 *   Options to use with the remote or local store, as passed to
 *   sparql_request.
 */
function _sparql_request($query, $endpoint) {
  // Initialize connection with the endpoint.
  $store = _sparql_init_remote_store($endpoint);

  // Execute the query.
  $rs = $store->query($query);
  if ($errors = $store->getErrors()) {
    // Log errors.
    foreach ($errors as $error) {
      trigger_error($error, E_USER_ERROR);
    }
    return NULL;
  }
  else {
    // Success!
    return $rs;
  }
}

/**
 * Sets up an ARC2 RDF local repository.
 *
 * @param $name
 *   The name of the local repository.
 * @param $endpoint
 *   Set to TRUE if this store should also be setup as a SPARQL endpoint.
 * @return
 *   An ARC2 store object.
 */
function _sparql_init_store($name, $endpoint = FALSE) {
  // @todo fix this. Error reporting is off because ARC2 throws strict warnings.
  error_reporting(0);

  $db_spec = $GLOBALS['databases']['default']['default'];

  $config = array(
    /* db */
    'db_name' => $db_spec['database'],
    'db_user' => $db_spec['username'],
    'db_pwd' => isset($db_spec['password']) ? $db_spec['password'] : '',
    /* store */
    'store_name' => $name,

    /* endpoint */
    'endpoint_features' => array(
      'select', 'construct', 'ask', 'describe',
      //'load', 'insert', 'delete',
      'dump' /* dump is a special command for streaming SPOG export */
    ),
    'endpoint_timeout' => 60, /* not implemented in ARC2 preview */
    'endpoint_read_key' => '', /* optional */
    'endpoint_write_key' => '', /* optional */
    'endpoint_max_limit' => 500, /* optional */
  );

  // If this site is exposing a SPARQL endpoint, instantiate the endpoint with
  // the endpoint class which can be used for HTTP-based data access.
  if ($endpoint) {
    $store = ARC2::getStoreEndpoint($config);
  }
  // Otherwise, instantiate a locally accessible store.
  else {
    $store = ARC2::getStore($config);
  }
  if (!$store->isSetUp()) {
    $store->setUp();
  }

  return $store;
}

/**
 * Sets up an ARC2 RDF remote store.
 *
 * @param $endpoint
 *   The remote SPARQL endpoint.
 * @return
 *   An ARC2 store object.
 */
function _sparql_init_remote_store($endpoint) {
  $endpoint_url = $endpoint->uri;

  // If there are query parameters that need to be added before ARC2 processing,
  // add them here. Filter the array to remove empty values.
  if (isset($endpoint->options['query_parameters'])) {
    $endpoint_url = url($endpoint_url, array('query' => array_filter($endpoint->options['query_parameters'])));
  }

  $config = array(
    /* remote endpoint */
    'remote_store_endpoint' => $endpoint_url,
  );

  /* instantiation */
  $store = ARC2::getRemoteStore($config);

  return $store;
}