Reading text from server socket stream

Question

I have a basic cd input program i've been trying to figure out the following problem for a while now, the user enters the artist and title etc and then a DOM (XML) file is created in memory this is then sent to the server. The server then echos back the results which is later printed on a html page by reading the replys from the server line by line.
The server must be run it listens for clients connecting the clients connect and send DOM documents through the following jsp code.
<%@page import="java.io.*"%>
<%@page import="java.net.*"%>
<%@page import="javax.xml.parsers.*"%>
<%@page import="org.w3c.dom.*"%>
<%@page import="org.apache.xml.serialize.*"%>
<%!
   public static final String serverHost = "cdserver";
   public static final int serverPort = 10151;
%>
<hr />
<pre>
<%
        Socket mySocket = null;          // socket object
        PrintWriter sockOut = null;      // to send data to the socket
        BufferedReader sockIn = null;    // to receive data from the socket
        try {
            //  #1 add line that creates a client socket
            mySocket = new Socket(serverHost, serverPort);
            // #2 add lines that create input and output streams
            //            attached to the socket you just created
             sockOut = new PrintWriter(mySocket.getOutputStream(), true);
             sockIn = new BufferedReader(new InputStreamReader(mySocket.getInputStream()));
        } catch (UnknownHostException e) {
            throw e; // This time the JSP can handle the exception, not us
        } catch (IOException e) {
            throw e; // This time the JSP can handle the exception, not us
String cdTitle, cdArtist, track1Title, track1Time, track1Rating;
// Retrieve the HTML form field values
cdTitle = request.getParameter("cdtitle");
cdArtist = request.getParameter("cdartist");
track1Title = request.getParameter("track1title");
track1Time = request.getParameter("track1time");
track1Rating = request.getParameter("track1rating");
// Create a new DOM factory, and from that a new DOM builder object
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
// Note that we are creating a new (empty) document
Document document = builder.newDocument();
// The root element of our document wil be <cd>
// It gets stored as the child node of the whole document (it is the root)
Element rootElement = document.createElement("cd");
document.appendChild(rootElement);
// Create an element for the CD title called <title>
Element cdTitleElement = document.createElement("title");
// Add a text code under the <title> element with the value that
// the user entered into the title field of the web form (cdTitle)
cdTitleElement.appendChild(document.createTextNode(cdTitle));
// Place the <title> element underneath the <cd> element in the tree
rootElement.appendChild(cdTitleElement);
// Create an <artist> element with the form data, place underneath <cd>
Element cdArtistElement = document.createElement("artist");
cdArtistElement.appendChild(document.createTextNode(cdArtist));
rootElement.appendChild(cdArtistElement);
// Create a <tracklist> element and place it underneath <cd> in the tree
// Note that it has no text node associated with it (it not a leaf node)
Element trackListElement = document.createElement("tracklist");
rootElement.appendChild(trackListElement);
// In this example we only have one track, so it is not necessary to
// use a loop (in fact it is quite silly)
// But the code below is included to demonstrate how you could loop
// through and add a set of different tracks one by one if you
// needed to (although you would need to have the track data already
// stored in an array or a java.util.Vector or similar
int numTracks = 1;
for (int i=0; i<numTracks; i++) {
  String trackNum = Integer.toString(i+1);
  Element trackElement = document.createElement("track");
  trackElement.setAttribute("id", trackNum);
  trackListElement.appendChild(trackElement);
  // Track title element called <title>, placed underneath <track>
  Element trackTitleElement = document.createElement("title");
  trackTitleElement.appendChild(document.createTextNode(track1Title));
  trackElement.appendChild(trackTitleElement);
  // Track time element called <time>, placed underneath <track>
  Element trackTimeElement = document.createElement("time");
  trackTimeElement.appendChild(document.createTextNode(track1Time));
  trackElement.appendChild(trackTimeElement);
  // Track rating element called <rating>, placed underneath <track>
  Element trackRatingElement = document.createElement("rating");
  trackRatingElement.appendChild(document.createTextNode(track1Rating));
  trackElement.appendChild(trackRatingElement);
OutputFormat format = new OutputFormat();
format.setIndenting(true);
// Create a new XMLSerializer that will be used to write out the XML
// This time we will serialize it to the socket
// #3 change this line so that it serializes to the socket,
// not to the "out" object
XMLSerializer serializer = new XMLSerializer(writer, format);
serializer.serialize(document);
        // Print out a message to indicate the end of the data, and
        // flush the stream so all the data gets sent now
        sockOut.println("<!--QUIT-->");
        sockOut.flush();
        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
        String fromServer;
        String fromUser;
         #4 add a while loop that reads text from the
        server socket input stream, line by line, and prints
        it out to the web page, using out.println(...);
        Note that because the reply from the server will contain
        XML, you will need to call upon the toHTMLString() method
        defined below to escape the < and > symbols so that they
        will display correctly in the web browser.
        Also note that as you receive the reply back from the
        server, you should look out for the special <!--QUIT-->
        string that will indicate when there is no more data
        to receive.
        while ((fromServer = sockIn.readLine()) != null) {
        out.println(sockIn.readLine());
            // If the reply from the server said "QUIT", exit from the
            // while loop by using a break statement.
            if (fromServer.equals("QUIT")) {
                out.println("Connection closed - good bye ...");
            // Print the text from the server out to the user's screen
            out.println("Reply from Server: " + fromServer);
            // Now read a line of text from the keyboard (typed by user)
            fromUser = stdIn.readLine();
            // If it wasn't null, print it out to the screen, and also
            // print a copy of it out to the socket
            if (fromUser != null) {
                out.println("Client: " + fromUser);
                sockOut.println(fromUser);
        // Close all the streams we have open, and then close the socket
        sockOut.close();
        sockIn.close();
        mySocket.close();
%>
I'm suppose to modify the commented sections labled with #.
#1,2 are correct but i have doubts on the 3rd and 4th modification.
for #3 i changed so i serializes to the socket not to the "out" object:
from
XMLSerializer serializer = new XMLSerializer(out, format);
to
XMLSerializer serializer = new XMLSerializer(writer, format);
with "out" it prints out some of the results entered but it just hangs i'm thinking it might be the while loop that i added in #4. If i changed it to serialize the socket XMLSerializer serializer = new XMLSerializer(writer, format); it doesn't print out nothing at all; just a blank screen where it hangs.
I can post the rest of the code (server thats in java and cdinput.html) but since i want to keep my post short and if required i'll post it later on i also omitted some of the code where it creates the DOM textnodes etc to keep my post short.

Answer 1

On your previous thread, why did you say the server was using http POST and application/xml content type when it quite obviously isn't, but a direct socket communication that abuses XML comments for message end delimiters?
The comments imply you need to wait for "<!--QUIT-->" on a line by itself, but your loop is waiting for "QUIT".
Pete