/**
  * Performs a RESTfulException instance, based on the current output class.
  */
 public function perform_exception(RESTfulException $ex)
 {
     header('X-PHP-Response-Code: ' . $ex->getErrorCode(), true, $ex->getErrorCode());
     $outputer = $this->build_outputer();
     $outputer->action($ex->getExceptionObject());
     exit;
 }