How can I listen on 2 ports in 1 app

Question

Here's a synapse of what I'm doing. I'm working on a graphical console program. Basically, I created a GUI interface, for a command prompt program. I'm basically trying to create a command prompt for the new millennium. It allows for multi-connections, has drop-down auto completes, syntax highlighting, object-oriented design, etc. I created it as a multi-threaded server and allows for remote and local connections. The way I have it designed is there are 2 main programs. The graphical client program and the server program. The server program is started whenever the client is started and accepts connections on port 9671. The graphical client can connect to local and remote machines. The client also can store information for multiple sessions in a single window which the user can juggle between. I decided that the server will consist of multiple programs similar to a Linux shell. Rather than build all the commands into the server I can create multiple programs for the server. Once the user needs to do something like copy a file I can call the File program, pass it the info, and have it handle the routine. I decided to have it where once the program is called it will connect to the main server on port 9672 so they can communicate. So what I'm wondering is how can I start my main server on 9671 and allow for connections on port 9672? Remember since I allow for multiple connections I need to be able to find out which thread started the session. I'm thinking either when I call the File program I can pass some thread id so it knows which program called it or I can create another program which runs on port 9672 and I can use the main program as a buffer between itself and the other server? Sorry for the long winded explanation but when I give too little info I usually get people asking me why I'm trying to do it:
<CODE>
package directlinkserver;
import java.io.*;
import java.sql.*;
import java.net.*;
import java.util.*;
public class DirectLinkServer {
static int portOpen1 = 9671;
public static void main(String[] args) {
try {
ServerSocket portListener1 = new ServerSocket(portOpen1);
DirectLinkServer userThreads = new DirectLinkServer();
while (1 == 1) {
Socket userConnection = portListener1.accept();
userThreads.new PortConnection(userConnection);
catch (Exception e) {
System.out.println (
"The server encountered a serious error. Server shut down.");
e.printStackTrace();
System.exit(0);
class PortConnection extends Thread {
Socket ourConnection;
BufferedReader serverInput;
PrintWriter serverOutput;
PortConnection(Socket userConnection) {
try {
ourConnection = userConnection;
serverInput = new BufferedReader(new InputStreamReader(userConnection.getInputStream()));
serverOutput = new PrintWriter(userConnection.getOutputStream(),true);
start();
} catch (Exception e) { System.out.println("An error occurred when a user attempted a connection."); }
public void run() {
serverOutput.println("Welcone to the Server.");
try {
serverOutput.close();
serverInput.close();
ourConnection.close();
} catch (Exception ex1) {}
public void commandConnect() {
</CODE>

Answer 1

Well, I'm still going to ask that. What's wrong with just using the one port? Also, your design seems questionable. How will the server know to start when the client starts, if the server isn't running already and listening on the appropriate port? It's a chicken and egg problem, and generally (every single case I can think of) the server just sits and runs, whether or not there are any clients.