Why is this node.js tcp server not writing back to Java client until it closes?

Question

Here is an example of a tcp server written in node.js I found:

net.createServer(function(sock) {

    // We have a connection - a socket object is assigned to the connection automatically
    console.log('CONNECTED: ' + sock.remoteAddress +':'+ sock.remotePort);

    // Add a 'data' event handler to this instance of socket
    sock.on('data', function(data) {

        console.log('DATA ' + sock.remoteAddress + ': ' + data);
        // Write the data back to the socket, the client will receive it as data from the server
        sock.write('You said "' + data + '"');

    });

    // Add a 'close' event handler to this instance of socket
    sock.on('close', function(data) {
        console.log('CLOSED: ' + sock.remoteAddress +' '+ sock.remotePort);
    });

}).listen(PORT, HOST);

console.log('Server listening on ' + HOST +':'+ PORT);

I am trying to use this as a basis for a tcp server which will have to handle multiple incoming connections at the same time. Here is a Java program I wrote to test this:

public static final String MESSAGE = "Hellow world";
    public static Semaphore networkLock;

    public static void main(String[] args) 
    {
        //writeMessage(MESSAGE);

        Thread[] threadPool = new Thread[10];
        networkLock = new Semaphore(1);

        for (int i = 0; i < threadPool.length; i++) 
        {
            threadPool[i] = new Thread(new Runnable() {

                @Override
                public void run() {
                    writeMessage(MESSAGE);

                }
            });

            threadPool[i].start();
        }

    }

    public static void writeMessage(String test)
    {
        try {
            if(sock == null || sock.isClosed())
                sock = new Socket(HOST, PORT);

            DataOutputStream out =
                    new DataOutputStream(sock.getOutputStream());
            System.out.println("Writting message");

            //networkLock.acquire();
            out.writeUTF(test);
            //networkLock.release();

              BufferedReader in = new BufferedReader(
                        new InputStreamReader(sock.getInputStream()));

              System.out.println("Waiting for reply");
              String input = in.readLine();

              System.out.println(input);
//            in.close();
//          out.close();
//          sock.close();

        } catch (UnknownHostException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
    }

When I start the client, the only output I get from the client is a "Writting message" and "Waiting for reply" a bunch of times. When I shut down the server, I finally get the responses of You said " Hellow world" along with a null or two thrown in usually. As for the server, it prints out the two print statements just fine. Do you think someone could help me out here?

Answer 1

The Java client is using in.readLine() which looks for a newline character in the input stream. However, the server is not writing a newline to the client socket.

So change this:

sock.write('You said "' + data + '"');

to this:

sock.write('You said "' + data + '"\n');