danielebarchiesi@4: <?php
danielebarchiesi@4: /*
danielebarchiesi@4:  * @file
danielebarchiesi@4:  * API function for running queries on external SPARQL endpoints.
danielebarchiesi@4:  */
danielebarchiesi@4: 
danielebarchiesi@4: define('SPARQL_ENDPOINT', 'endpoint');
danielebarchiesi@4: 
danielebarchiesi@4: /**
danielebarchiesi@4:  * Implements hook_help().
danielebarchiesi@4:  */
danielebarchiesi@4: function sparql_help($path, $arg = NULL) {
danielebarchiesi@4:   switch ($path) {
danielebarchiesi@4:     case 'admin/settings/sparql':
danielebarchiesi@4:       return '<p>' . t('The sparql module provides an interface for other modules to perform sparql queries') . '</p>'; // TODO
danielebarchiesi@4:   }
danielebarchiesi@4: }
danielebarchiesi@4: 
danielebarchiesi@4: /**
danielebarchiesi@4:  * Executes a SPARQL query.
danielebarchiesi@4:  *
danielebarchiesi@4:  * @param $query
danielebarchiesi@4:  *   The SPARQL query to execute.
danielebarchiesi@4:  * @param $endpoint
danielebarchiesi@4:  *   An endpoint object, as returned by SPARQL Registry.
danielebarchiesi@4:  * @return
danielebarchiesi@4:  *   The SPARQL results.
danielebarchiesi@4:  */
danielebarchiesi@4: function sparql_request($query, $endpoint) {
danielebarchiesi@4:   $rows = _sparql_request($query, $endpoint);
danielebarchiesi@4:   return $rows;
danielebarchiesi@4: }
danielebarchiesi@4: 
danielebarchiesi@4: function sparql_get_store($name, $type = 'store') {
danielebarchiesi@4:   $db = $GLOBALS['databases']['default']['default'];
danielebarchiesi@4:   $name = "sparql_store_$name";
danielebarchiesi@4: 
danielebarchiesi@4:   $config = array(
danielebarchiesi@4:     /* db */
danielebarchiesi@4:     'db_host' => $db['host'],
danielebarchiesi@4:     'db_name' => $db['database'],
danielebarchiesi@4:     'db_user' => $db['username'],
danielebarchiesi@4:     'db_pwd' => $db['password'],
danielebarchiesi@4:     /* store */
danielebarchiesi@4:     'store_name' => $name,
danielebarchiesi@4: 
danielebarchiesi@4:     /* endpoint */
danielebarchiesi@4:     'endpoint_features' => array(
danielebarchiesi@4:       'select', 'construct', 'ask', 'describe',
danielebarchiesi@4:       'load', 'insert', 'delete',
danielebarchiesi@4:       'dump' /* dump is a special command for streaming SPOG export */
danielebarchiesi@4:     ),
danielebarchiesi@4:     'endpoint_timeout' => 60, /* not implemented in ARC2 preview */
danielebarchiesi@4:     'endpoint_read_key' => '', /* optional */
danielebarchiesi@4:     'endpoint_write_key' => 'somekey', /* optional */
danielebarchiesi@4:     'endpoint_max_limit' => 500, /* optional */
danielebarchiesi@4:   );
danielebarchiesi@4: 
danielebarchiesi@4:   /* instantiation */
danielebarchiesi@4:   if ($type == SPARQL_ENDPOINT) {
danielebarchiesi@4:     $store = ARC2::getStoreEndpoint($config);
danielebarchiesi@4:   }
danielebarchiesi@4:   else {
danielebarchiesi@4:     $store = ARC2::getStore($config);
danielebarchiesi@4:   }
danielebarchiesi@4:   if (!$store->isSetUp()) {
danielebarchiesi@4:     $store->setUp();
danielebarchiesi@4:   }
danielebarchiesi@4:   return $store;
danielebarchiesi@4: }
danielebarchiesi@4: 
danielebarchiesi@4: /**
danielebarchiesi@4:  * Runs a query against an endpoint.
danielebarchiesi@4:  *
danielebarchiesi@4:  * @param $query
danielebarchiesi@4:  *   The SPARQL query to execute.
danielebarchiesi@4:  * @param $endpoint
danielebarchiesi@4:  *   The endpoint to try the query against.
danielebarchiesi@4:  * @options
danielebarchiesi@4:  *   Options to use with the remote or local store, as passed to
danielebarchiesi@4:  *   sparql_request.
danielebarchiesi@4:  */
danielebarchiesi@4: function _sparql_request($query, $endpoint) {
danielebarchiesi@4:   // Initialize connection with the endpoint.
danielebarchiesi@4:   $store = _sparql_init_remote_store($endpoint);
danielebarchiesi@4: 
danielebarchiesi@4:   // Execute the query.
danielebarchiesi@4:   $rs = $store->query($query);
danielebarchiesi@4:   if ($errors = $store->getErrors()) {
danielebarchiesi@4:     // Log errors.
danielebarchiesi@4:     foreach ($errors as $error) {
danielebarchiesi@4:       trigger_error($error, E_USER_ERROR);
danielebarchiesi@4:     }
danielebarchiesi@4:     return NULL;
danielebarchiesi@4:   }
danielebarchiesi@4:   else {
danielebarchiesi@4:     // Success!
danielebarchiesi@4:     return $rs;
danielebarchiesi@4:   }
danielebarchiesi@4: }
danielebarchiesi@4: 
danielebarchiesi@4: /**
danielebarchiesi@4:  * Sets up an ARC2 RDF local repository.
danielebarchiesi@4:  *
danielebarchiesi@4:  * @param $name
danielebarchiesi@4:  *   The name of the local repository.
danielebarchiesi@4:  * @param $endpoint
danielebarchiesi@4:  *   Set to TRUE if this store should also be setup as a SPARQL endpoint.
danielebarchiesi@4:  * @return
danielebarchiesi@4:  *   An ARC2 store object.
danielebarchiesi@4:  */
danielebarchiesi@4: function _sparql_init_store($name, $endpoint = FALSE) {
danielebarchiesi@4:   // @todo fix this. Error reporting is off because ARC2 throws strict warnings.
danielebarchiesi@4:   error_reporting(0);
danielebarchiesi@4: 
danielebarchiesi@4:   $db_spec = $GLOBALS['databases']['default']['default'];
danielebarchiesi@4: 
danielebarchiesi@4:   $config = array(
danielebarchiesi@4:     /* db */
danielebarchiesi@4:     'db_name' => $db_spec['database'],
danielebarchiesi@4:     'db_user' => $db_spec['username'],
danielebarchiesi@4:     'db_pwd' => isset($db_spec['password']) ? $db_spec['password'] : '',
danielebarchiesi@4:     /* store */
danielebarchiesi@4:     'store_name' => $name,
danielebarchiesi@4: 
danielebarchiesi@4:     /* endpoint */
danielebarchiesi@4:     'endpoint_features' => array(
danielebarchiesi@4:       'select', 'construct', 'ask', 'describe',
danielebarchiesi@4:       //'load', 'insert', 'delete',
danielebarchiesi@4:       'dump' /* dump is a special command for streaming SPOG export */
danielebarchiesi@4:     ),
danielebarchiesi@4:     'endpoint_timeout' => 60, /* not implemented in ARC2 preview */
danielebarchiesi@4:     'endpoint_read_key' => '', /* optional */
danielebarchiesi@4:     'endpoint_write_key' => '', /* optional */
danielebarchiesi@4:     'endpoint_max_limit' => 500, /* optional */
danielebarchiesi@4:   );
danielebarchiesi@4: 
danielebarchiesi@4:   // If this site is exposing a SPARQL endpoint, instantiate the endpoint with
danielebarchiesi@4:   // the endpoint class which can be used for HTTP-based data access.
danielebarchiesi@4:   if ($endpoint) {
danielebarchiesi@4:     $store = ARC2::getStoreEndpoint($config);
danielebarchiesi@4:   }
danielebarchiesi@4:   // Otherwise, instantiate a locally accessible store.
danielebarchiesi@4:   else {
danielebarchiesi@4:     $store = ARC2::getStore($config);
danielebarchiesi@4:   }
danielebarchiesi@4:   if (!$store->isSetUp()) {
danielebarchiesi@4:     $store->setUp();
danielebarchiesi@4:   }
danielebarchiesi@4: 
danielebarchiesi@4:   return $store;
danielebarchiesi@4: }
danielebarchiesi@4: 
danielebarchiesi@4: /**
danielebarchiesi@4:  * Sets up an ARC2 RDF remote store.
danielebarchiesi@4:  *
danielebarchiesi@4:  * @param $endpoint
danielebarchiesi@4:  *   The remote SPARQL endpoint.
danielebarchiesi@4:  * @return
danielebarchiesi@4:  *   An ARC2 store object.
danielebarchiesi@4:  */
danielebarchiesi@4: function _sparql_init_remote_store($endpoint) {
danielebarchiesi@4:   $endpoint_url = $endpoint->uri;
danielebarchiesi@4: 
danielebarchiesi@4:   // If there are query parameters that need to be added before ARC2 processing,
danielebarchiesi@4:   // add them here. Filter the array to remove empty values.
danielebarchiesi@4:   if (isset($endpoint->options['query_parameters'])) {
danielebarchiesi@4:     $endpoint_url = url($endpoint_url, array('query' => array_filter($endpoint->options['query_parameters'])));
danielebarchiesi@4:   }
danielebarchiesi@4: 
danielebarchiesi@4:   $config = array(
danielebarchiesi@4:     /* remote endpoint */
danielebarchiesi@4:     'remote_store_endpoint' => $endpoint_url,
danielebarchiesi@4:   );
danielebarchiesi@4: 
danielebarchiesi@4:   /* instantiation */
danielebarchiesi@4:   $store = ARC2::getRemoteStore($config);
danielebarchiesi@4: 
danielebarchiesi@4:   return $store;
danielebarchiesi@4: }