private function serializeResponse(Request $request)
 {
     $formatter = $request->getFormatter();
     MessageWriter::writeObject($request, $formatter);
     $byteBuffer = $formatter->getBytes();
     ob_clean();
     header("Content-type: " . $formatter->getContentType());
     header("Content-length: " . strlen($byteBuffer));
     $formatter->cleanup();
     print $byteBuffer;
     ob_end_flush();
 }