public synchronized Client addClient(Client client) {
		if (client != null) {
			try {
				listClient.put(client);
				logger.info("Client: " + client.getName()
						+ " successfully added!");
			} catch (InterruptedException e) {
				e.getMessage();
			} catch (NullPointerException e) {
				e.getMessage();
			}
			return client;
		} else {
			return null;
		}
	}