private function validateRequest($serverKey)
 {
     // If the request comes from the local computer, then don't require authorization,
     // otherwise check the headers
     if (HttpUtils::isLocal()) {
         return true;
     } else {
         $providedServerkey = HttpUtils::getHeader(HEADER_SERVER_KEY);
         if (empty($serverKey)) {
             throw new MashapeException(EXCEPTION_EMPTY_SERVERKEY, EXCEPTION_XML_CODE);
         }
         if ($providedServerkey != null && md5($serverKey) == $providedServerkey) {
             return true;
         }
         return false;
     }
 }