Java socket programming problem - sockets

Question

Hey,
I am trying to run this socket programming code.
This is the code on the server side -
package sockettest;
import java.net.*;
import java.io.*;
public class Server {
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = null;
try
{
serverSocket = new ServerSocket(139);
}
catch (IOException e)
{
System.err.println("not able to listen on port");
System.exit(1);
}
Socket clientSocket = null;
try
{
clientSocket = serverSocket.accept();
}
catch (IOException e)
{
System.err.println("Accept failed.");
System.exit(1);
}
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); // Out is Outputstream is used to write to the Client .
BufferedReader in = new BufferedReader( new InputStreamReader(clientSocket.getInputStream())); // in is used to read the Client's input.
String inputLine, outputLine;
out.println("Hey! . Who are you?"); // Writes to client as "Hey! . Who are you?"
while ((inputLine = in.readLine()) != null)
{
// Reads the input from the Client. if it is "bye" the program ends.
if (inputLine.equalsIgnoreCase("Bye"))
{
out.println("Bye");
break;
}
else
{
out.println("Hello Mr. " + inputLine);
}
}
out.close();
in.close();
clientSocket.close();
serverSocket.close();
}
}
This is the code running on the client side -
import java.io.*;
import java.net.*;
public class Client
{
public static void main(String[] args) throws IOException {
Socket kkSocket = null;
PrintWriter out = null;
BufferedReader in = null;
try
{
kkSocket = new Socket("192.168.2.3", 139);
out = new PrintWriter(kkSocket.getOutputStream(), true); // Out may be used to write to server from the client
in = new BufferedReader(new InputStreamReader(kkSocket.getInputStream())); // in will be used to read the lines sent by the Server.
}
catch (UnknownHostException e)
{
System.err.println("Unidentified host.");
System.exit(1);
}
catch (IOException e)
{
System.err.println("Couldn't get I/O for the connection to.");
System.exit(1);
}
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
String fromServer;
String fromClient;
while ((fromServer = in.readLine()) != null) {
System.out.println("Server: " + fromServer);
if (fromServer.equals("Bye"))
break;
fromClient = stdIn.readLine();
if (fromClient != null) {
System.out.println("Client: " + fromClient);
out.println(fromClient);
}
}
out.close();
in.close();
stdIn.close();
kkSocket.close();
}
}
I'm running the codes on eclipse in both the client and the server side. Using netstat -an command in cmd prompt, i can see that a connection has been established between the client and the server but i cannot communicate and eclipse is not showing any output too. What seems to be wrong??

Answer 1

You haven't told us what the problem is. However, from a cursory glance at your code, I would advise against listening on port 139 as this is already used by NetBios under Windows and may cause a conflict.

Answer 2

also your Server code is missing
the initialization of inputLine,
e.g
String inputline = "";
before the while loop

Answer 3

keep in mind that Socket's are blocked if you read or write...
your client is reading all the time because it waits for every information on the server
until it is null
and your server also reads all the time and is waiting for any input..
so as long as server and client are waiting for input, no one will receive any data.
try to think of a protocol to communicate between the server and the client.
e.g
Sever to Client: Hello Who are you?
Client receives Data and replies: Client
Server receives Information: You Are now authorized, what ya gonna do?
and so on ^^
also out.flush() is needed to send a message