diff --git a/rdf_indexer.info b/rdf_indexer.info
index a904e7f..0495c4b 100644
--- a/rdf_indexer.info
+++ b/rdf_indexer.info
@@ -8,3 +8,7 @@ package = RDF
 
 files[] = service.inc
 files[] = includes/callback_entity_public.inc
+files[] = service.arc2.inc
+files[] = service.virtuoso.inc
+
+configure = admin/config/search/search_api
diff --git a/rdf_indexer.module b/rdf_indexer.module
index b3ed750..f492b85 100644
--- a/rdf_indexer.module
+++ b/rdf_indexer.module
@@ -13,6 +13,11 @@ function rdf_indexer_search_api_service_info() {
     'description' => t('<p>Index items using an RDF store server.</p>'),
     'class' => 'RdfIndexerArc2StoreService',
   );
+  $services['rdf_virtuoso_service'] = array(
+    'name' => t('RDF indexer service for Virtuoso'),
+    'description' => t('<p>Index items using the Virtuoso triplestore.</p>'),
+    'class' => 'RdfIndexerVirtuosoService',
+  );
   return $services;
 }
 
diff --git a/service.arc2.inc b/service.arc2.inc
new file mode 100644
index 0000000..d6e5783
--- /dev/null
+++ b/service.arc2.inc
@@ -0,0 +1,115 @@
+<?php
+
+/**
+ * Search service class using an RDF store server.
+ */
+class RdfIndexerArc2StoreService extends RdfIndexerBaseService {
+
+  /*
+   * Loads ARC2 store this index is connected to.
+   */
+  public function getStore(SearchApiIndex $index) {
+    return arc2_store_get_store($index->server()->options['store_id']);
+  }
+
+  /**
+   * Form callback. Might be called on an uninitialized object - in this case,
+   * the form is for configuring a newly created server.
+   *
+   * Returns an empty form by default.
+   *
+   * @return array
+   *   A form array for setting service-specific options.
+   */
+  public function configurationForm(array $form, array &$form_state) {
+    ctools_include('export');
+    if (module_exists('arc2_store')) {
+      foreach (ctools_export_crud_load_all('arc2_store_settings') as $store) {
+        if (empty($store->disabled)) {
+          $options[$store->store_id] = $store->label . ' (' . $store->store_id . ')';
+        }
+      }
+    }
+
+    if (empty($options)) {
+      $form['store_id'] = array(
+        '#markup' => t('No ARC2 store found. Please install the ARC2 store module and create some stores.'),
+      );
+    }
+    else {
+      $form['store_id'] = array(
+        '#type' => 'select',
+        '#title' => t('ARC2 store'),
+        '#description' => t('The ARC2 store where the data should be indexed.'),
+        '#options' => $options,
+        '#default_value' => $this->options['store_id'],
+        '#required' => TRUE,
+      );
+    }
+    return $form;
+  }
+
+  /**
+   * View this server's settings. Output can be HTML or a render array, a <dl>
+   * listing all relevant settings is preferred.
+   *
+   * The default implementation does a crude output as a definition list, with
+   * option names taken from the configuration form.
+   */
+  public function viewSettings() {
+    $output = '';
+    $store = arc2_store_settings_load($this->options['store_id']);
+    if (!empty($store->settings['endpoint_enabled'])) {
+      $url = url($store->settings['endpoint_path'], array('absolute' => TRUE));
+      $output .= "<dl>\n  <dt>";
+      $output .= t('SPARQL endpoint');
+      $output .= "</dt>\n  <dd>";
+      $output .= l($url, $url);
+      $output .= '</dd>';
+      $output .= "\n</dl>";
+    }
+
+    return $output;
+  }
+  
+  /*
+   * Index an item to the given store
+   *
+   * @param $item
+   *   The rdfx_get_rdf_model() resource
+   * @param $store
+   *   The ARC2 Store
+   * @param $graph
+   *   The optional graph URI to update (unused for ARC2)
+   */
+  public function indexItem($item, $store, $graph = FALSE) {
+    $store->insert($item->index, $item->uri);
+  }
+  
+  /*
+   * Delete an item from the given store
+   *
+   * @param $item
+   *   The rdfx_get_rdf_model() resource
+   * @param $store
+   *   The ARC2 Store
+   * @param $graph
+   *   The optional graph URI to update (unused for ARC2)
+   */
+  public function deleteItem($item, $store, $graph = FALSE) {
+    $store->delete('', $item);
+  }
+  
+  /*
+   * Clear the ARC2 store
+   *
+   * @param $store
+   *   The ARC2 Store
+   * @param $graph
+   *   The optional graph URI to update (unused for ARC2)
+   */
+  public function clearGraph($store, $graph = FALSE) {
+    $store->reset();
+  }
+  
+}
\ No newline at end of file
diff --git a/service.inc b/service.inc
index f0d5b21..3472054 100644
--- a/service.inc
+++ b/service.inc
@@ -3,128 +3,31 @@
 /**
  * Search service class using an RDF store server.
  */
-class RdfIndexerArc2StoreService extends SearchApiAbstractService {
+class RdfIndexerBaseService extends SearchApiAbstractService {
 
   public function __construct(SearchApiServer $server) {
     parent::__construct($server);
   }
-
-  /**
-   * Form callback. Might be called on an uninitialized object - in this case,
-   * the form is for configuring a newly created server.
-   *
-   * Returns an empty form by default.
-   *
-   * @return array
-   *   A form array for setting service-specific options.
+  
+  /*
+   * Return a representation of the triplestore
    */
-  public function configurationForm(array $form, array &$form_state) {
-    ctools_include('export');
-    if (module_exists('arc2_store')) {
-      foreach (ctools_export_crud_load_all('arc2_store_settings') as $store) {
-        if (empty($store->disabled)) {
-          $options[$store->store_id] = $store->label . ' (' . $store->store_id . ')';
-        }
-      }
-    }
-
-    if (empty($options)) {
-      $form['store_id'] = array(
-        '#markup' => t('No ARC2 store found. Please install the ARC2 store module and create some stores.'),
-      );
-    }
-    else {
-      $form['store_id'] = array(
-        '#type' => 'select',
-        '#title' => t('ARC2 store'),
-        '#description' => t('The ARC2 store where the data should be indexed.'),
-        '#options' => $options,
-        '#default_value' => $this->options['store_id'],
-        '#required' => TRUE,
-      );
-    }
-
-    return $form;
+  public function getStore(SearchApiIndex $index) {
+    return FALSE;
   }
-
-  /**
-   * View this server's settings. Output can be HTML or a render array, a <dl>
-   * listing all relevant settings is preferred.
-   *
-   * The default implementation does a crude output as a definition list, with
-   * option names taken from the configuration form.
+  /*
+   * Index an item to the given store
    */
-  public function viewSettings() {
-    $output = '';
-    $store = arc2_store_settings_load($this->options['store_id']);
-    if (!empty($store->settings['endpoint_enabled'])) {
-      $url = url($store->settings['endpoint_path'], array('absolute' => TRUE));
-      $output .= "<dl>\n  <dt>";
-      $output .= t('SPARQL endpoint');
-      $output .= "</dt>\n  <dd>";
-      $output .= l($url, $url);
-      $output .= '</dd>';
-      $output .= "\n</dl>";
-    }
-
-    return $output;
-  }
-
-  /**
-   * Notifies this server that it is about to be deleted from the database and
-   * should therefore clean up, if appropriate.
-   *
-   * Note that you shouldn't call the server's save() method, or any
-   * methods that might do that, from inside of this method as the server isn't
-   * present in the database anymore at this point.
-   *
-   * By default, deletes all indexes from this server.
+  public function indexItem($item, $store, $graph = FALSE) {}
+  /*
+   * Delete an item from the given store
    */
-  public function preDelete() {
-    // Only react on real deletes, not on reverts.
-    // @see https://drupal.org/node/1414078
-    // This method could be removed once the above issue is fixed.
-    if ($this->server->hasStatus(ENTITY_IN_CODE)) {
-      return;
-    }
-    $indexes = search_api_index_load_multiple(FALSE, array('server' => $this->server->machine_name));
-    foreach ($indexes as $index) {
-      $this->removeIndex($index);
-    }
-  }
-
-  /**
-   * Add a new index to this server.
-   *
-   * @param SearchApiIndex $index
-   *   The index to add.
+  public function deleteItem($item, $store, $graph = FALSE) {}
+  /*
+   * Clear a graph from the given store
    */
-  public function addIndex(SearchApiIndex $index) {
-    if (module_exists('search_api_multi') && module_exists('search_api_views')) {
-      views_invalidate_cache();
-    }
-  }
-
-  /**
-   * Notify the server that the indexed field settings for the index have
-   * changed.
-   * If any user action is necessary as a result of this, the method should
-   * use drupal_set_message() to notify the user.
-   *
-   * @param SearchApiIndex $index
-   *   The updated index.
-   *
-   * @return
-   *   TRUE, if this change affected the server in any way that forces it to
-   *   re-index the content. FALSE otherwise.
-   */
-  public function fieldsUpdated(SearchApiIndex $index) {
-    if (module_exists('search_api_multi') && module_exists('search_api_views')) {
-      views_invalidate_cache();
-    }
-    return TRUE;
-  }
-
+  public function clearGraph($store, $graph = FALSE) {}
+  
   /**
    * Index the specified items.
    *
@@ -155,8 +58,8 @@ class RdfIndexerArc2StoreService extends SearchApiAbstractService {
    *   If indexing was prevented by a fundamental configuration error.
    */
   public function indexItems(SearchApiIndex $index, array $items) {
-    // Loads ARC2 store this index is connected to.
-    $store = arc2_store_get_store($index->server()->options['store_id']);
+    
+    $store = $this->getStore($index);
 
     // @todo use documents and merge them before sending to ARC2.
     // $documents = array();
@@ -166,7 +69,7 @@ class RdfIndexerArc2StoreService extends SearchApiAbstractService {
       try {
         // Builds an RDF resource for the entity.
         $rdf = rdfx_get_rdf_model($index->item_type, $id);
-        $store->insert($rdf->index, $rdf->uri);
+        $this->indexItem($rdf, $store);
         $ret[] = $id;
       }
       catch (Exception $e) {
@@ -175,7 +78,7 @@ class RdfIndexerArc2StoreService extends SearchApiAbstractService {
     }
     return $ret;
   }
-
+  
   /**
    * Delete items from an index on this server.
    *
@@ -192,30 +95,91 @@ class RdfIndexerArc2StoreService extends SearchApiAbstractService {
    *   this server should be cleared (then, $ids has to be 'all').
    */
   public function deleteItems($ids = 'all', SearchApiIndex $index = NULL) {
-    // Loads ARC2 store this index is connected to.
-    $store = arc2_store_get_store($index->server()->options['store_id']);
-
+  
+    $store = $this->getStore($index);
     try {
       // Emtpy the local store.
       if ($ids === 'all') {
-        $store->reset();
+        
+        //this clears the graph for a given store, but there may be more than one index storing data at the graph
+        //$this->clearGraph($store);
+        $ids = array_keys(entity_load($index->item_type));
       }
-      elseif (is_array($ids)) {
+      if (is_array($ids)) {
         // Contructs the URI of the graph for each entity ID and deletes it.
-        foreach($ids as $id) {
-          $entity = entity_load_single($index->item_type, $id);
-          $uri = rdfx_resource_uri($index->item_type, $entity);
-          $store->delete('', $uri);
+        foreach ($ids as $id) {
+          $rdf = rdfx_get_rdf_model($index->item_type, $id);
+          //in case there are more than one index
+          foreach($rdf->index as $subject => $triples){
+            $this->deleteItem($subject, $store);
+          }
         }
+      } else {
+        throw new Exception('Could not delete the items specified because they were not in the form of an array');
       }
     }
-    catch(Exception $e) {
+    catch (Exception $e) {
       watchdog_exception('rdf_indexer', $e, '%type while deleting items from server @server: !message in %function (line %line of %file).', array('@server' => $this->server->name));
     }
   }
 
+  
+  /**
+   * Notifies this server that it is about to be deleted from the database and
+   * should therefore clean up, if appropriate.
+   *
+   * Note that you shouldn't call the server's save() method, or any
+   * methods that might do that, from inside of this method as the server isn't
+   * present in the database anymore at this point.
+   *
+   * By default, deletes all indexes from this server.
+   */
+  public function preDelete() {
+    // Only react on real deletes, not on reverts.
+    // @see https://drupal.org/node/1414078
+    // This method could be removed once the above issue is fixed.
+    if ($this->server->hasStatus(ENTITY_IN_CODE)) {
+      return;
+    }
+    $indexes = search_api_index_load_multiple(FALSE, array('server' => $this->server->machine_name));
+    foreach ($indexes as $index) {
+      $this->removeIndex($index);
+    }
+  }
+  
+  /**
+   * Add a new index to this server.
+   *
+   * @param SearchApiIndex $index
+   *   The index to add.
+   */
+  public function addIndex(SearchApiIndex $index) {
+    if (module_exists('search_api_multi') && module_exists('search_api_views')) {
+      views_invalidate_cache();
+    }
+  }
+  
+  /**
+   * Notify the server that the indexed field settings for the index have
+   * changed.
+   * If any user action is necessary as a result of this, the method should
+   * use drupal_set_message() to notify the user.
+   *
+   * @param SearchApiIndex $index
+   *   The updated index.
+   *
+   * @return
+   *   TRUE, if this change affected the server in any way that forces it to
+   *   re-index the content. FALSE otherwise.
+   */
+  public function fieldsUpdated(SearchApiIndex $index) {
+    if (module_exists('search_api_multi') && module_exists('search_api_views')) {
+      views_invalidate_cache();
+    }
+    return TRUE;
+  }
+  
   public function search(SearchApiQueryInterface $query) {
     throw new SearchApiException(t('The RDF indexer service does not support search. Please query the SPARQL endpoint directly if the RDF store provide such service.'));
   }
-
-}
+}
\ No newline at end of file
diff --git a/service.virtuoso.inc b/service.virtuoso.inc
new file mode 100644
index 0000000..565244d
--- /dev/null
+++ b/service.virtuoso.inc
@@ -0,0 +1,411 @@
+<?php
+
+/**
+ * Search service class using an RDF store server.
+ */
+class RdfIndexerVirtuosoService extends RdfIndexerBaseService {
+  
+  /*
+   * The external store
+   */
+  public function getStore(SearchApiIndex $index) {
+    return $this->options;
+  }
+  
+  public function getTriplestoreUrl() {
+    if ( !isset($this->options['url']) ) {
+      watchdog('rdf_indexer', "The URL of the Virtuoso Server has not been specified.", WATCHDOG_WARNING);
+    }
+    
+    return $this->options['url'];
+  }
+  
+  public function getRequestHeaders() {
+    $headers = array(
+      'Content-Type' => 'application/x-www-form-urlencoded',
+    );
+    if ( !empty($this->options['authorization']) ) {
+      $headers['Authorization'] = $this->options['authorization'];
+    }
+    return $headers;
+  }
+
+  /**
+   * Form callback. Might be called on an uninitialized object - in this case,
+   * the form is for configuring a newly created server.
+   *
+   * Returns an empty form by default.
+   *
+   * @return array
+   *   A form array for setting service-specific options.
+   */
+  public function configurationForm(array $form, array &$form_state) {
+    global $base_url;
+    
+    $settings = isset($this->options) ? $this->options : array();
+    $form['url'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Virtuoso SPARQL Endpoint URL'),
+      '#description' => t('The Virtuoso SPARQL Endpoint URL where data will be inserted and deleted via basic authentication. Typically, http://example.com:8890/sparql-auth'),
+      '#default_value' => isset($settings['url']) ? $settings['url'] : '',
+      '#required' => TRUE,
+    );
+    $form['graph'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Graph URI'),
+      '#description' => t('The URI of the graph where data will be inserted and deleted.'),
+      '#default_value' => isset($settings['graph']) ? $settings['graph'] : $base_url,
+      '#required' => TRUE,
+    );
+    $form['test_query'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Test SPARQL Query'),
+      '#description' => t('A test query that can be used to verify a connection can be established.'),
+      '#default_value' => isset($settings['test_query']) ? $settings['test_query'] : 'SELECT ?s WHERE {?s ?p ?o} LIMIT 1',
+      '#required' => TRUE,
+    );
+    $form['query_params'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Additional Query Parameters'),
+      '#description' => t('Specify other query parameters that should be added to SPARQL Update requests.'),
+      '#default_value' => isset($settings['query_params']) ? $settings['query_params'] : 'default-graph-uri=&format=text%2Fhtml&timeout=0&debug=on',
+    );
+    $form['username'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Username'),
+      '#description' => t('The username of the Virtuoso account with SPARQL/Update privileges'),
+      '#default_value' => isset($settings['username']) ? $settings['username'] : '',
+      '#required' => TRUE,
+    );   
+    //assume that 'Administer Search API' permission is valid enough to view the password 
+    $form['credential'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Credential'),
+      '#description' => t('The credential of the Virtuoso account with SPARQL/Update privileges'),
+      '#default_value' => isset($settings['credential']) ? $settings['credential'] : '',
+      '#required' => TRUE,
+    ); 
+    $form['authorization'] = array(
+      '#type' => 'hidden',
+      '#value' => isset($settings['authorization']) ? $settings['authorization'] : '',
+    );    
+    return $form;
+  }
+
+  /**
+   * View this server's settings. Output can be HTML or a render array, a <dl>
+   * listing all relevant settings is preferred.
+   *
+   * The default implementation does a crude output as a definition list, with
+   * option names taken from the configuration form.
+   */
+  public function viewSettings() {
+    $settings = isset($this->options) ? $this->options : array();
+    if ( !empty($settings) ) {
+      require './includes/password.inc';
+      $output = "<dl>\n  <dt>";
+      $output .= t('Virtuoso SPARQL endpoint');
+      $output .= "</dt>\n  <dd>";
+      $output .= l($settings['url'], $settings['url']);
+      $output .= "</dd>\n  <dt>";
+      $output .= t('Graph URI');
+      $output .= "</dt>\n<dd>";
+      $output .= $settings['graph'];
+      $output .= "</dd>\n  <dt>";
+      $output .= t('Test Query');
+      $output .= "</dt>\n<dd>";
+      $output .= $settings['test_query'];
+      $output .= "</dd>\n  <dt>";
+      $output .= t('Additional Query Parameters');
+      $output .= "</dt>\n<dd>";
+      $output .= $settings['query_params'];
+      $output .= "</dd>\n  <dt>";
+      $output .= t('Username');
+      $output .= "</dt>\n  <dd>";
+      $output .= $settings['username'];
+      $output .= "</dd>\n  <dt>";
+      $output .= t('Credential');
+      $output .= "</dt>\n <dd>";
+      $output .= user_hash_password($settings['credential']);
+      $output .= "</dd>\n</dl>";
+      return $output;
+    } 
+    else {
+      return 'Virtuoso has not been configured.';
+    }
+  }
+  
+  /*
+   * Index an item to the given store
+   *
+   * @param $item
+   *   The rdfx_get_rdf_model() resource
+   * @param $store
+   *   The Virtuoso Store options from the SearchApiServer
+   * @param $graph
+   *   The optional graph URI to update
+   * @param $options
+   *    Array provided to expansion of the function
+   *    Currently, it supports returning the query string
+   */
+  public function indexItem($item, $store, $graph = FALSE, $options = array()) {
+    $graph = $graph ? $graph : $store['graph'];
+    $beginning = 'INSERT DATA INTO GRAPH <' . $graph . '> { ';
+    $end = ' } ';
+    $query = '';
+    $queries = array();
+    $triple_count = 0;
+    foreach($item->index as $subject => $triples){
+      //clear out the item in case it already exists 
+      $this->deleteItem($subject, $store, $graph, array('no_log' => TRUE));
+      
+      if( function_exists('drush_log') ){
+        drush_log('Re-indexing ' . $subject, 'ok');
+      }
+      
+      foreach($triples as $predicate => $value){
+        foreach($value as $triple){
+          $object = '';
+          if( isset($triple['type']) && $triple['type'] == 'uri' ){
+            $object .= '<'.$triple['value'].'>';
+          } else {
+            if( !empty($triple['datatype']) ){
+              $object .= '"'.$this->prepareString($triple['value']).'"^^'.$triple['datatype'];
+            } else if( isset($triple['lang']) && !empty($triple['lang']) ){
+              $object .= '"'.$this->prepareString($triple['value']).'"@'.$triple['lang'];
+            } else {
+              $object .= '"'.$this->prepareString($triple['value']).'"';
+            }
+          }
+          $query .= ' <'.$subject.'> <'.$predicate.'> '.$object.' . ';
+          $triple_count += 1;
+          //this is to avoid  ERROR:
+          //Virtuoso 37000 Error SP031: SPARQL: Internal error: The length of generated SQL text has exceeded 10000 lines of code
+          if( $triple_count == 500 ){
+            $queries[] = $beginning . $query . $end;
+            $triple_count = 0;
+            $query = '';
+          }
+        }
+      }
+    }
+    if( strlen($query) > 0 ){
+      $queries[] = $beginning . $query . $end;
+    }
+
+    if( isset($options['display']) ){
+      $query = '';
+      foreach($queries as $q){
+        $query .= $q;
+      }
+      return htmlspecialchars($query);
+    } else {
+      $result = '';
+      foreach($queries as $query){
+        $response = $this->executeQuery($query);
+        if( $response ){ $result .= $response; }
+        else if( function_exists('drush_log') ){
+          drush_log($query, 'error');
+        }
+      }
+      return $result;
+    }
+  }
+  
+  /**
+   * Delete the given URI from the triplestore
+   * 
+   * @param $item
+   *   The rdfx_get_rdf_model() resource
+   * @param $store
+   *   The Virtuoso Store options from the SearchApiServer
+   * @param $graph
+   *   The optional graph URI to update
+   * @param $options
+   *    Array provided to expansion of the function
+   *    Currently, it supports returning the query string
+   */
+  public function deleteItem($item, $store, $graph = FALSE, array $options = array()) {
+    $graph = $graph ? $graph : $store['graph'];
+    $query = 'WITH <' . $graph . '> DELETE { ?s ?p ?o } WHERE { ?s ?p ?o FILTER (?s = <' . $item . '>)}';
+    
+    if( !isset($options['no_log']) && function_exists('drush_log') ){
+      drush_log('Removing ' . $item, 'ok');
+    }
+      
+    if ( isset($options['display']) ) {
+      return htmlspecialchars($query);
+    } 
+    else {
+      return $this->executeQuery($query);
+    }
+  }
+  
+  /*
+   * Clear the Virtuoso store of all values from this index
+   * *** NEEDS UPDATING TO GET ALL ENTITIES FOR THIS INDEX
+   *     AND REMOVE ONLY THOSE ***
+   *
+   * @param $store
+   *   The Virtuoso Store options from the SearchApiServer
+   * @param $graph
+   *   The optional graph URI to update
+   * @param $options
+   *    Array provided to expansion of the function
+   *    Currently, it supports returning the query string
+   */
+  public function clearGraph($store, $graph = FALSE) {
+    $graph = $graph ? $graph : $store['graph'];
+    $query = 'CLEAR GRAPH <' . $graph . '>';
+    if ( isset($options['display']) ) {
+      return htmlspecialchars($query);
+    } 
+    else {
+      return $this->executeQuery($query);
+    }
+  }
+    
+  /*
+   * Connect to the triplestore and run a query
+   *
+   * Virtuoso at the /sparql-auth URL implements Digest Authentication
+   */
+  protected function executeQuery($query) {
+    $url = $this->getTriplestoreUrl();
+    $config = $this->options;
+ 
+    $data = 'query=' . urlencode($query);
+    if( !empty($config['query_params']) ){
+      $data .= '&' . $config['query_params'];
+    } 
+    $content = array(
+      'method' => 'POST',
+      'headers' => $this->getRequestHeaders(),
+      'data' => $data,
+    ); 
+    $response = drupal_http_request($url, $content);
+    if( $response->code == 200 ) {
+      return $response->data;
+    }
+    
+    //Unauthorized
+    elseif ( $response->code == 401 ) {
+    
+      $uri = parse_url($this->getTriplestoreUrl());
+      $this->authenticate($response->headers['www-authenticate'], $uri['path']);
+      //the authenticate method above will have added the new auth headers 
+      $content['headers'] = $this->getRequestHeaders(); 
+      $response = drupal_http_request($url, $content);
+      if ( $response->code == 200 ) {
+        watchdog('rdf_indexer', "@data.", array('@data' => $response->data), WATCHDOG_INFO);
+        return $response->data;
+      } 
+      else {
+        watchdog('rdf_indexer', "Could not authenticate with the triplestore while trying to run query: @query", array('@query' => $query), WATCHDOG_ERROR);
+      }
+    } 
+    else {
+      watchdog('rdf_indexer', "Unknown error[HTTP=@code] occured while trying to run the query: @query", array('@code' => $response->code, '@query' => $query), WATCHDOG_ERROR);
+    }
+    return FALSE;
+  }
+  
+  /*
+   * Build the Authorization header for Virtuoso
+   *
+   * @param $digest
+   *    The digest information passed from Virtuoso via the WWW-Authenticate header
+   * @param $uri
+   *    The uri path at which the original request was made
+   */
+  protected function authenticate($data, $uri) {
+    $value = explode(' ', $data, 2);
+    $type = $value[0];
+    
+    switch ($type) {
+    
+      case 'Digest':{
+        $digest = array();
+        $parts = explode(", ", $value[1]);
+        foreach ($parts as $element) {
+          $bits = explode("=", $element);
+          $digest[$bits[0]] = str_replace('"', '', $bits[1]);
+        }
+    
+        if ( $digest['qop'] == 'auth') {
+          $cnonce = time();
+          $ncvalue = '00000001';
+          $noncebit = $digest['nonce'] . ':' . $ncvalue . ':' . $cnonce . ':auth:' . md5("POST:" . $uri);
+          $A = md5($this->server->options['username'] . ':' . $digest['realm'] . ':' . $this->server->options['credential']);
+          $respdig = md5("$A:$noncebit");
+          $auth_header = 'Digest username="' . $this->server->options['username'] . '", realm="' . $digest['realm'];
+          $auth_header .= '", nonce="' . $digest['nonce'] . '", uri="' . $uri . '", algorithm=' . $digest['algorithm'];
+          $auth_header .= ', response="' . $respdig . '", opaque="' . $digest['opaque'] . '", qop=' . $digest['qop'];
+          $auth_header .= ', nc=' . $ncvalue . ', cnonce="' . $cnonce . '"';
+      
+          //update the authorization info
+          $config = $this->options;
+          $config['authorization'] = $auth_header;
+          $this->server->options = $config;
+          $this->server->save();
+      
+        } 
+        else {
+          watchdog('rdf_indexer', "Could not authenticate with the triplestore at URI: @uri because the Digest qop != 'auth'. It was '@qop'", array('@uri' => $uri, '@qop' => $digest['qop'] ), WATCHDOG_ERROR);
+        }
+        break;
+      } //end of 'Digest'
+    } //end of switch
+  }
+  
+  /*
+   * Clean up literal string values for processing
+   */
+  protected function prepareString($object = FALSE) {
+    if ( !empty($object) ) {
+      //strip out control characters
+      if ( !ctype_print($object) ) {
+        $object = preg_replace('/[\x00-\x1F\x80-\xFF]/', '', $object);
+      }
+      //escape backslash
+      $object = str_replace( "\\", "\\\\", $object );
+      //escape double quotes
+      $object = str_replace( "\"", "\\\"", $object );
+    }
+    return $object;
+  }
+
+  /*
+   * Set a drupal message with the insert/delete queries 
+   * or the response data for a given entity type and entity ID
+   *
+   * @param $entity_type
+   *    The type of entity to test
+   *
+   * @param $id
+   *    The entity ID
+   *
+   * @param $display
+   *    A boolean flag that if TRUE just displays the queries. 
+   *    If FALSE, the queries are executed and the response data 
+   *    is displayed instead
+   *
+   *  @param $toggle
+   *    A string where 'insert' runs just the insert routine,
+   *    'delete' runs just the delete routine, and
+   *    'both' runs both insert and delete routines
+   */
+  public function testQueries($entity_type, $id, $display = TRUE, $toggle = 'both') {
+    $options = $display ? array('display' => $display) : array();
+    $rdf= rdfx_get_rdf_model($entity_type, $id);
+    
+    $messages = array();
+    if ( $toggle == 'both' || $toggle == 'insert') {
+      $messages['insert'] = $this->indexItem($rdf, $this->options, FALSE, $options);
+    }
+    if ( $toggle == 'both' || $toggle == 'delete') {
+      $messages['delete'] = $this->deleteItem($rdf->uri, $this->options, FALSE, $options);
+    }
+    return $messages;
+  }
+}