Trying to make a simple echo client server program work between two computers

Question

I have been trying to resolve this issue but with no success so finally i am here to get some help from experts.

I just wanted to make a simple client server program work between two computers.

The server will reside in my laptop which is connected to the internet through a linksys router.

The client will reside in a university computer. I scped the file to a university computer and then i run it through ssh.

Now also two things worth noting is that i have also disabled firewall in my computer as well as i have configured port forwaring in my linksys router i.e it will forward request to the port to my ipaddress. I have also made my ipadddress static.

Here is the server code to reside in my laptop.

/* EchoServer.java
 *
 * Copyright (c) 2000 Sean Walton and Macmillan Publishers.  Use may be in
 * whole or in part in accordance to the General Public License (GPL).
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
*/

/*****************************************************************************/
/*** EchoServer.java                                                       ***/
/***                                                                       ***/
/*****************************************************************************/

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

public class EchoServer
{
    public EchoServer(int portnum)
    {
        try
        {
            server = new ServerSocket(portnum);
        }
        catch (Exception err)
        {
            System.out.println(err);
        }
    }

    public void serve()
    {
        try
        {
            while (true)
            {

                Socket client = server.accept();

                BufferedReader r = new BufferedReader(new InputStreamReader(client.getInputStream()));
                PrintWriter w = new PrintWriter(client.getOutputStream(), true);
                w.println("Welcome to the Java EchoServer.  Type 'bye' to close.");
                String line;
                do
                {
                    line = r.readLine();
                    if ( line != null )
                        w.println("Got: "+ line);
                }
                while ( !line.trim().equals("bye") );
                client.close();
            }
        }
        catch (Exception err)
        {
            System.err.println(err);
        }
    }

    public static void main(String[] args)
    {
        EchoServer s = new EchoServer(3000);
        s.serve();
    }

    private ServerSocket server;
}

Here is the client code that will reside in university computer.

/* EchoClient.java
 *
 * Copyright (c) 2000 Sean Walton and Macmillan Publishers.  Use may be in
 * whole or in part in accordance to the General Public License (GPL).
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
*/

/*****************************************************************************/
/*** EchoClient.java                                                       ***/
/***                                                                       ***/
/*****************************************************************************/

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

public class EchoClient
{
    public static void main(String[] args)
    {
        try
        {
            Socket s = new Socket("my static ip address here", 3000);
            BufferedReader r = new BufferedReader(new InputStreamReader(s.getInputStream()));
            PrintWriter w = new PrintWriter(s.getOutputStream(), true);
            BufferedReader con = new BufferedReader(new InputStreamReader(System.in));
            String line;
            do
            {
                line = r.readLine();
                if ( line != null )
                    System.out.println(line);
                line = con.readLine();
                w.println(line);
            }
            while ( !line.trim().equals("bye") );
        }
        catch (Exception err)
        {
            System.err.println(err);
        }
    }
}

When i run it(both). The client program runs and it halts without any error. It just hangs.

I appreciate your help very much!

Answer 1

Actually when your client code try to connect to server and send "string massage" to server at this time server read inputstream (by bufferreader) i.e. line = r.readLine(); // server code

here it would wait for \n or \r or \n\r (Line Feed, Carriage Return )at the end of String.

so you need to append last character as \n or \r or \n\r both side while sending massage to server or vis-versa..

.
.
.
    do
                {
                    line = r.readLine();
                    line = line +"\n"; // Add this line
                    if ( line != null )
                        System.out.println(line);
                    line = con.readLine();
                    w.println(line);
                }
.
.
.

@Client code