Apache Mina Server

public class ServerActivity extends Activity {

    private NioSocketAcceptor acceptor;
    private static final int SERVER_PORT = 9123;
    private IoSession session;

    // Set this to false to use object serialization instead of custom codec.
    private static final boolean USE_CUSTOM_CODEC = true;

    private class ServerSessionHandler extends IoHandlerAdapter {

        private final Logger LOGGER = LoggerFactory.getLogger(ServerSessionHandler.class);

        @Override
        public void sessionOpened(IoSession s) {
            session = s;
            // set idle time to 60 seconds
            session.getConfig().setIdleTime(IdleStatus.BOTH_IDLE, 60);
        }

        @Override
        public void messageReceived(IoSession session, Object message) {
            // client only sends AddMessage. otherwise, we will have to identify
            // its type using instanceof operator.
            AddMessage am = (AddMessage) message;
            String value = am.getValue();
            EditText et = (EditText)findViewById(R.id.messageBoard);
            et.append(value);
        }

        @Override
        public void sessionIdle(IoSession session, IdleStatus status) {
            //LOGGER.info("Disconnecting the idle.");
            // disconnect an idle client
            session.close(true);
        }

        @Override
        public void exceptionCaught(IoSession session, Throwable cause) {
            // close the connection on exceptional situation
            session.close(true);
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_server);
    }

    public void startServerButtonClicked(View v){
        acceptor = new NioSocketAcceptor();
        acceptor.getSessionConfig().setReadBufferSize(2048);

        // Prepare the service configuration.
        if (USE_CUSTOM_CODEC) {
            acceptor.getFilterChain().addLast("codec", new ProtocolCodecFilter(new MessageProtocolCodecFactory(true)));
        } else {
            acceptor.getFilterChain().addLast("codec", new ProtocolCodecFilter(new ObjectSerializationCodecFactory()));
        }

        acceptor.getFilterChain().addLast("logger", new LoggingFilter());
        acceptor.setHandler(new ServerSessionHandler());

        try {
            acceptor.bind(new InetSocketAddress(SERVER_PORT));
        } catch (IOException e) {
            e.printStackTrace();
        }

        Log.d("***************************", "Listening on port " + SERVER_PORT);
    }

    public void sendMessageButtonClicked(View v){

        if (session == null){
            Log.d("***************************", "Session is null");
            return;
        }

        ResultMessage rm = new ResultMessage();
        rm.setSequence(1); // copy sequence
        EditText et = (EditText)findViewById(R.id.message);
        rm.setValue(et.getText().toString());
        rm.setOk(true);
        session.write(rm);
    }
}