code: private void executeGetOperation(HttpServletRequest request, HttpServletResponse response)
          throws IOException, ClassNotFoundException {
          if (request.getContentLength() > 0) {
              response.setStatus(HttpServletResponse.SC_NO_CONTENT);
              ObjectInputStream input = new ObjectInputStream(new BufferedInputStream(request.getInputStream()));
              CommandPayload paylod = (CommandPayload) input.readObject();
              events.put(currentCall, paylod);
          } else {
              if (events.containsKey(currentCall) && !events.get(currentCall).isExecuted()) {
                  response.setStatus(HttpServletResponse.SC_OK);
                  ObjectOutputStream output = new ObjectOutputStream(response.getOutputStream());
                  output.writeObject(events.remove(currentCall));
                  output.flush();
                  output.close();
              } else {
                  response.setStatus(HttpServletResponse.SC_NO_CONTENT);
              }
          }
      }
docs: Container-to-Client command execution