ClientGUI locking up after transmitting one object

Make sure the other end is actually continually reading what's being sent

Yes, i have a while loop to continually read objects..

Put a timestamping debugging SOP in both ends and let me know what gets printed

Sorry, have absolutely no idea what that means..

ok, thanks mccarl..Theres a few classes for the server..ServerGUI, Server (which accepts a connection and then offloads responsibility to the HandleConnection class)..Please see attached code

************ ServerGUI **************
import java.awt.*;
import java.awt.event.*;
import java.util.Vector;

import javax.swing.JFrame;

public class ServerGUI extends JFrame implements ActionListener {
	public static final int defaultWidth = 80, defaultHeight = 40;

	   private Button  startButton;
	   private Button  stopButton;
	   Server server = new Server();
	   
	   public ServerGUI() {
		   
	        super("ServerGUI");
		    Panel topPanel = new Panel();
	        
	        startButton = new Button("Start Server");
	        startButton.setBackground(Color.white);
	        startButton.addActionListener(this);
	        topPanel.add(startButton);
	        
	        stopButton = new Button("Stop Server");
	        stopButton.addActionListener(this);
	        topPanel.add(stopButton);

	        this.add(topPanel, BorderLayout.NORTH);
//	        this.add(c, BorderLayout.CENTER);

	        this.setSize(400, 400);
	        this.setVisible(true);
	        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
	    }  
	 

public static void main(String[] args) {
    new ServerGUI();
}

 public void actionPerformed(ActionEvent e) {

	System.out.println("Action Event");
//	Object source = e.getSource();

	   if 
		(e.getSource() == startButton) {
		 System.out.println("Start button pressed.");
		server.startServer();}
	   
	 
	   else if
		  (e.getSource() == stopButton){			  
		   System.out.println("Stop button pressed.");
}	

}  } 
 

************ Server ***************

import java.net.*;
import java.util.Enumeration;
import java.io.*;

public class Server //extends ServerGUI
{
	protected static StreamService ss;    //Create WhiteboardService object
	private String clients[] = new String[20];
	private int clientCount = 0;
	
    public static void startServer()
    {
 //   	Enumeration e = null;
        ServerSocket serverSocket = null;
        try 
        {
            serverSocket = new ServerSocket(5050);
            System.out.println("Server has started listening on port 5050");
        } 
        catch (IOException e) 
        {
            System.out.println("Error: Cannot listen on port 5050: " + e);
            System.exit(1);
        }
        
        while (true) // infinite loop - loops once for each client
        {
            Socket clientSocket = null;
            try 
            {
                clientSocket = serverSocket.accept();  // returns
                System.out.println("Server has just accepted socket connection from a client " + 
                		clientSocket.getInetAddress().getHostAddress() + " " + clientSocket.getPort());
            } 
            catch (IOException e) 
            {
                System.out.println("Accept failed: 5050 " + e);
                break;
            }	

	       // Create the Handle Connection object - only create it
            ss = new StreamService();
            HandleConnection con = new HandleConnection(clientSocket, ss );

            if (con == null) //If it failed send and error message
            {
                try 
                {
                    ObjectOutputStream os = new ObjectOutputStream(clientSocket.getOutputStream());
                    os.writeObject("error: Cannot open socket thread");
                    os.flush();
                    os.close();
                } 
                catch (Exception ex)  //failed to even send an error message
                {
                    System.out.println("Cannot send error back to client:  5050 " + ex);
                }
            }
            else { con.init(); } // otherwise we have not failed to create the HandleConnection object
				 // run it now.
        }
        try  // do not get here at the moment 
        {
            System.out.println("Closing server socket.");
            serverSocket.close();
        } 
        catch (IOException e) 
        {
            System.err.println("Could not close server socket. " + e.getMessage());
        }
    }
}

************** HandleConnection ***************
/*// The Handle connection class - that deals will all client requests directly
// by Derek Molloy

import java.net.*;
import java.io.*;
import java.util.*;


public class HandleConnection
{

    private Socket clientSocket;			// Client socket object
    private ObjectInputStream is;			// Input stream
    private ObjectOutputStream os;			// Output stream
    
    // The constructor for the connecton handler

    public HandleConnection(Socket clientSocket) 
    {
        this.clientSocket = clientSocket;
    }

    // The main execution method 

    public void init() 
    {
        String inputLine;

        try 
        {
            this.is = new ObjectInputStream(clientSocket.getInputStream());
            this.os = new ObjectOutputStream(clientSocket.getOutputStream());
            while (this.readCommand()) {}

         } 
         catch (IOException e) 
         {
                e.printStackTrace();
         }
    }

    // Receive and process incoming command from client socket 

    private boolean readCommand() 
    {
        Object obj = null;

        try 
        {
            obj = is.readObject();
            System.out.println("Shape converted to string = " + obj.toString());
        } 
        catch (Exception e) 
        {
            obj = null;
        }
        if (obj == null) 
        {
            this.closeSocket();
            return false;
        }
        
        return true;

    }
        

    private void send(Object o) 
    {
        try 
        {
            System.out.println("Sending " + o);
            this.os.writeObject(o);
            this.os.flush();
        } 
        catch (Exception ex) 
        {
            ex.printStackTrace();
        }
    }
    
    // Send a pre-formatted error message to the client 
    public void sendError(String msg) 
    {
        this.send("error:" + msg);	//remember a string IS-A object!
    }
    
    // Close the client socket 
    public void closeSocket()		//close the socket connection
    {
        try 
        {
            this.os.close();
            this.is.close();
            this.clientSocket.close();
        } 
        catch (Exception ex) 
        {
            System.err.println(ex.toString());
        }
    }

}

*/

// The Handle connection class - that deals will all client requests directly
// by Derek Molloy

import java.net.*;
import java.io.*;
import java.util.*;

public class HandleConnection
{

    private Socket clientSocket;			// Client socket object
    private ObjectInputStream is;			// Input stream
    private ObjectOutputStream os;
    private StreamService streamService;
    private String clients[] = new String[20];
	private static int clientCount = 0;

    public HandleConnection(Socket clientSocket, StreamService ss) 
    {
    	System.out.println("In handle connection constructor");
    	this.streamService = ss;
        this.clientSocket = clientSocket;
        clientCount++;
        System.out.println("Client count is : " + clientCount);
        // init();
    }

    // The main execution method 
    public void init() 
    {
        String inputLine;
        System.out.println("Got to init()");

        try 
        {
            this.is = new ObjectInputStream(clientSocket.getInputStream());
            this.os = new ObjectOutputStream(clientSocket.getOutputStream());                      
            while (this.readCommand()) {}

         } 
         catch (IOException e) 
         {
                e.printStackTrace();
         }
    }


    private boolean readCommand() 
    {
       Object obj = null;

        try 
        {
       // 	System.out.println(obj.getClass());
            obj = is.readObject();
            System.out.println("is.readObject()");
            
            if(obj instanceof FootballStream){
            	System.out.println(obj.getClass());
            	sendReply(obj);
            	FootballStream fs = (FootballStream) obj;
            	streamService.addFootyMessage(fs);
            	System.out.println("In handle connection, first element of received vector is " + 
            			fs.footyVector.firstElement());
            }
            else if(obj instanceof MusicStream){
            	System.out.println(obj.getClass());
            	sendReply(obj);
            	MusicStream ms = (MusicStream) obj;
 //           	streamService = new StreamService();
            	streamService.addMusicMessage(ms);
 //           	System.out.println("In handle connection, first element of received vector is " + 
 //           			ms.musicVector.firstElement());
            }
            
            
    //        rc.shapeRepaint((Vector<Shape>) obj);
            
        } 
        catch (Exception e) 
        {
        	System.out.println("In exception");
            obj = null;
            e.printStackTrace();
        }
        if (obj == null) 
        {
        //    this.closeSocket();
            return false;
        }
        
        return true;

    }
        
   private void sendReply(Object o) 
    {
        try 
        {        	
            this.os.writeObject(o);
            this.os.flush();
            System.out.println("Reply sent to client.");
        } 
        catch (Exception ex) 
        {
            ex.printStackTrace();
        }
    }
    
   public void closeSocket()		//close the socket connection
    {
        try 
        {
        	System.out.println("About to close client socket..");
            this.os.close();
            this.is.close();
            this.clientSocket.close();
        } 
        catch (Exception ex) 
        {
            System.err.println(ex.toString());
        }
    }

}

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I think the HandleConnection class will be the one causing the issue...

Hi mccarl,

Thanks for your detailed reply..With regards to your first point, i agree..Obviously i shouldnt be creating a new connection for each object..I will see about fixing that..
With regards to your second point, yes we actually have to make our application multi-threaded..Well, i will leave it for the night for now (its 2 in the morning!)..I will let you know how i get on tomorrow and points will be coming your way :)

Hi mccarl,

I fixed the code so that the connectToServer() is only called once when the ClientTransmit is first instantatiated. Its working fine now. Thanks for your help. I will give you the points now.

Good to hear that you are making progress!!