/**
  * Try to determine all request headers
  *
  * @return array
  */
 public function getRequestHeaders()
 {
     $headers = array();
     foreach ($this->data->getAll() as $key => $value) {
         if ('HTTP_' === substr($key, 0, 5)) {
             $headers[substr($key, 5)] = $value;
         }
     }
     return $headers;
 }