public void demarrer() {
        mySocket = null;
        try {
            mySocket = new DatagramSocket(6789); // port convenu avec les clients
            byte[] buffer = new byte[1000];
            while (true) {
                DatagramPacket request = new DatagramPacket(buffer,
                        buffer.length);
                mySocket.receive(request); // réception bloquante

                Requete requete = Requete.unmarshall(request);
                new Thread(new RequestHandler(requete)).start();
            }
        } catch (SocketException e) {
            System.out.println("Socket: " + e.getMessage());
        } catch (IOException e) {
            System.out.println("IO: " + e.getMessage());
        }

        finally {
            if (mySocket != null)
                mySocket.close();
        }

    }