LMAX-Exchange/nanofix

        FixClient client = FixClientFactory.createFixClient("hostname", 2000);
        client.subscribeToAllMessages(new FixMessageHandler() {
            @Override
            public void onFixMessage(FixMessage fixMessage) {
                System.out.println("Received fix message " + fixMessage.toFixString());
            }
        });

        client.connect();

        client.registerTransportObserver(new ConnectionObserver() {
            ...
            @Override
            public void connectionClosed() {
                System.out.println("TCP Connection Closed.");
            }
        });

        client.send(new FixMessageBuilder().messageType(MsgType.LOGIN).username("hello").build());

        final FixClient listeningClient = FixClientFactory.createFixClient(2000);
        listeningClient.subscribeToAllMessages(new FixMessageHandler() {
            @Override
            public void onFixMessage(FixMessage fixMessage) {
                System.out.println("Received fix message " + fixMessage.toFixString());
                listeningClient.send(new FixMessageBuilder().messageType(MsgType.LOGIN).username("hello back").build());
            }
        });

        listeningClient.listen();

        listeningClient.registerTransportObserver(new ConnectionObserver() {
            @Override
            public void connectionEstablished() {
                System.out.println("TCP Connection Established.");
            }

            @Override
            public void connectionClosed() {
                System.out.println("TCP Connection Closed.");
            }
        });