@Override
public void messageReceived(IoSession session, Object message) {
System.err.println("rcv : " + message);
CoapMessage resp = reg.respond((CoapMessage) message, session);
System.err.println("resp : " + resp);
session.write(resp);
count++;
if (count >= 100_000) {
System.err.println("time for 100k msg : " + (System.currentTimeMillis() - start));