public Event receive() throws IOException, ClassNotFoundException{
		DatagramPacket dp = null;
		dp = server.receive();
		if(dp == null) return null;
		log.trace("յݰlength=" + dp.getLength() + " from=" + dp.getAddress().getHostAddress());
		ByteArrayInputStream bis = new ByteArrayInputStream(dp.getData());
		ObjectInputStream ois = new ObjectInputStream(bis);
		Object o = ois.readObject();
		log.info("յ¼" + o);
		return (Event) o;
	}