private function HandleQueryResponse($sth)
 {
     $found = array();
     while ($obj = $sth->fetchObject()) {
         $session = new Session();
         $session->UserID = $obj->UserID;
         $session->SessionID = $obj->SessionID;
         $session->SecureSessionID = $obj->SecureSessionID;
         $session->SceneID = $obj->SceneID;
         $session->ScenePosition = Vector3::Parse($obj->ScenePosition);
         $session->SceneLookAt = Vector3::Parse($obj->SceneLookAt);
         $session->LastUpdate = $obj->LastUpdate;
         if (!is_null($obj->ExtraData)) {
             $session->ExtraData = $obj->ExtraData;
         } else {
             $session->ExtraData = "{}";
         }
         $found[] = $session->toOSD();
     }
     log_message('debug', 'returning ' . count($found));
     header("Content-Type: application/json", true);
     echo '{ "Success": true, "Sessions": [' . implode(',', $found) . '] }';
     exit;
 }