simple socket programming

[Mohamed Sanaulla]

Can you be elaborate on who is the Client and Server? From Your earlier post, I assume - Your Friend's computer is the client and your computer as the Server.

abalfazl hossein wrote:The story is, I ran this program on his computer, for first time, His computer be as server and client,as time that I ran on my computer, On my computer it works, But on his computer it throws that exception.

Please be specific on these facts- Are both Client and Server running on same machine- Your or your friends? or both running on different machines? In which case- who is the server and client. To connect to a computer you need to know a way to communicate with it- Knowing its Public IP address and the port on which the application is running.

[abalfazl hossein]

both Client and Server are running on same machine.

because I decide to show him my program, Then first I decide to show him how it works,But it does not work....

and my friend make

and me

[Henry Wong]

A "connection reset" means that the network plumbing went down; and it is a notice from the system. It could be caused by anything. The network can be configured to timeout the connection (on either side). The other side could have closed the connection. Or there could even be some sort of firewall running, that prevents the connection (even on the same machine).

IOW, the only way to debug it, is to probably load up a network sniffer to hunt it down.

Henry

[abalfazl hossein]

Ok,I went to his home this night, and it doesn't work again!


I use netbeans5.5 in his home.

I don't think I come again to his home.

[Henry Wong]

abalfazl hossein wrote:My IP address [?]: 94.183.229.216 [Whois] [Reverse IP]
My IP country code: IR
My IP address country: ip address flag Iran, Islamic Republic of
....

Ahhh... Okay. Why are you telling us this?

Henry

[abalfazl hossein]

I try again!

My other fired lives in another city, I sent for him server code:

package socketserver;
import java.io.*;
import java.net.*;
/**
 *
 * @author Administrator
 */
public class Main {


    public static void main(String args[]) {
// declaration section:
// declare a server socket and a client socket for the server
// declare an input and an output stream
        ServerSocket echoServer = null;
        String line;
        DataInputStream is;
        PrintStream os;
        Socket clientSocket = null;
// Try to open a server socket on port 9999
// Note that we can't choose a port less than 1023 if we are not
// privileged users (root)
        try {
           echoServer = new ServerSocket(12000);
        }
        catch (IOException e) {
           System.out.println(e);
        }
// Create a socket object from the ServerSocket to listen and accept
// connections.
// Open input and output streams
    try {
           clientSocket = echoServer.accept();
           is = new DataInputStream(clientSocket.getInputStream());
           os = new PrintStream(clientSocket.getOutputStream());
// As long as we receive data, echo that data back to the client.
           while ((line = is.readLine()) != null) {
             
             os.println(line);
           }
        }
    catch (IOException e) {
           System.out.println(e);
        }
    }


    /**
     * @param args the command line arguments
     */
    

}

this is for client

package sockettest;
import java.io.*;
import java.net.*;
/**
 *
 * @author Administrator
 */
public class Main {



    public static void main(String[] args) {
// declaration section:
// smtpClient: our client socket
// os: output stream
// is: input stream
        Socket smtpSocket = null;
        DataOutputStream os = null;
        DataInputStream is = null;
// Initialization section:
// Try to open a socket on port 25
// Try to open input and output streams
        try {
            smtpSocket = new Socket("109.230.87.28", 12000);
            os = new DataOutputStream(smtpSocket.getOutputStream());
            is = new DataInputStream(smtpSocket.getInputStream());
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: hostname");
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: hostname");
        }
// If everything has been initialized then we want to write some data
// to the socket we have opened a connection to on port 25
    if (smtpSocket != null && os != null && is != null) {
            try {
// The capital string before each colon has a special meaning to SMTP
// you may want to read the SMTP specification, RFC1822/3
        os.writeBytes("HELO\n");
                os.writeBytes("MAIL From: [e-mail]\n");
                os.writeBytes("RCPT To: [e-mail]\n");
                os.writeBytes("DATA\n");
                os.writeBytes("From: [e-mail]\n");
                os.writeBytes("Subject: testing\n");
                os.writeBytes("Hi there\n"); // message body
                os.writeBytes("\n.\n");
        os.writeBytes("QUIT");
// keep on reading from/to the socket till we receive the "Ok" from SMTP,
// once we received that then we want to break.
                String responseLine;
                while ((responseLine = is.readLine()) != null) {
                    System.out.println("Server: " + responseLine);
                    if (responseLine.indexOf("Ok") != -1) {
                      break;
                    }
                }
// clean up:
// close the output stream
// close the input stream
// close the socket
        os.close();
                is.close();
                smtpSocket.close();
            } catch (UnknownHostException e) {
                System.err.println("Trying to connect to unknown host: " + e);
            } catch (IOException e) {
                System.err.println("IOException:  " + e);
            }
        }
    }

}

[abalfazl hossein]

May someone answer?

[Ulf Dittmer]

It looks like both client and server exhibit the Don't println to a Socket bug. (There may be other problems, but that one jumped out at me.)

[abalfazl hossein]

package sockettest;
import java.io.*;
import java.net.*;
/**
 *
 * @author Administrator
 */
public class Main {



    public static void main(String[] args) {
// declaration section:
// smtpClient: our client socket
// os: output stream
// is: input stream
        Socket smtpSocket = null;
        DataOutputStream os = null;
        DataInputStream is = null;

        try {
            smtpSocket = new Socket("109.230.85.156", 12000);
            os = new DataOutputStream(smtpSocket.getOutputStream());
            is = new DataInputStream(smtpSocket.getInputStream());
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: hostname");
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: hostname");
        }

    if (smtpSocket != null && os != null && is != null) {
            try {

                  os.writeBytes("HELO\n");
                  os.writeBytes("Hi there\n"); // message body
                  os.writeBytes("\n.\n");
                  os.writeBytes("QUIT");

                String responseLine;
                while ((responseLine = is.readLine()) != null) {
                    System.out.println("Server: " + responseLine);
                    if (responseLine.indexOf("Ok") != -1) {
                      break;
                    }
                }
// clean up:
// close the output stream
// close the input stream
// close the socket
                os.flush();
                
                os.close();
                is.close();
                smtpSocket.close();
            } catch (UnknownHostException e) {
                System.err.println("Trying to connect to unknown host: " + e);
            } catch (IOException e) {
                System.err.println("IOException:  " + e);
            }
        }
    }

}

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

public class Main {


    public static void main(String args[]) {
// declaration section:
// declare a server socket and a client socket for the server
// declare an input and an output stream
        ServerSocket echoServer = null;
        String line;
        DataInputStream is;
        PrintStream os;
        Socket clientSocket = null;
// Try to open a server socket on port 9999
// Note that we can't choose a port less than 1023 if we are not
// privileged users (root)
        try {
           echoServer = new ServerSocket(12000);
        }
        catch (IOException e) {
           System.out.println(e);
        }
// Create a socket object from the ServerSocket to listen and accept
// connections.
// Open input and output streams
    try {
           clientSocket = echoServer.accept();
           is = new DataInputStream(clientSocket.getInputStream());
           os = new PrintStream(clientSocket.getOutputStream());
// As long as we receive data, echo that data back to the client.
           while ((line = is.readLine()) != null) {
             
             os.println(line);
           }
        }
    catch (IOException e) {
           System.out.println(e);
        }
    }


}

run:
Server: HELO
Server: Hi there
Server:
Server: .
ok
Ok

When I type Ok, Nothing happened

and also it does not print ouit

[Ulf Dittmer]

Ulf Dittmer wrote:It looks like both client and server exhibit the Don't println to a Socket bug. (There may be other problems, but that one jumped out at me.)

[Mihai Calin]

i want to test this program,
Is it possible my computer be client and server?

[abalfazl hossein]

Yes, But you must use your IP, I also wanted to check through the internet, If you like please send PM for me,

[abalfazl hossein]

String responseLine;  
                while ((responseLine = is.readLine()) != null) {  
                    System.out.println("Server: " + responseLine);  
                    if (responseLine.indexOf("Ok") != -1) {  
                      break;  
                    }  
                }  

What is the usage of this code in program?

[Mohamed Sanaulla]

That code snippet - reads the Line from the stream and then prints it on the standard output. If the line contains "Ok" it breaks out of the loop.

Anyways, I see that this thread is marked as Solved.

[abalfazl hossein]

package socketserver;
import java.io.*;
import java.net.*;

public class Main {


    public static void main(String args[]) {
// declaration section:
// declare a server socket and a client socket for the server
// declare an input and an output stream
        ServerSocket echoServer = null;
        String line;
        BufferedReader bufferchar=null;
        PrintStream os;
        Socket clientSocket = null;

        try {
           echoServer = new ServerSocket(12000);
        }
        catch (IOException e) {
           System.out.println(e);
        }
// Create a socket object from the ServerSocket to listen and accept
// connections.
// Open input and output streams
    try {
           clientSocket = echoServer.accept();
           bufferchar=new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
           os = new PrintStream(clientSocket.getOutputStream());
// As long as we receive data, echo that data back to the client.
           while ((line = bufferchar.readLine()) != null) {
             
             os.println(line);
             os.flush();
           }
        }
    catch (IOException e) {
           System.out.println(e);
        }
    }
}

package sockettest;
import java.io.*;
import java.net.*;
/**
 *
 * @author Administrator
 */
public class Main {



    public static void main(String[] args) {
// declaration section:
// smtpClient: our client socket
// os: output stream
// is: input stream
        Socket ClientSocket = null;
        //DataOutputStream os = null;
        //DataInputStream is = null;
        BufferedWriter inchar=null;
        BufferedReader bufferchar=null;



        try {
            ClientSocket = new Socket("100.230.85.132", 12000);
            
            inchar=new BufferedWriter(new OutputStreamWriter(ClientSocket.getOutputStream()));
            bufferchar=new BufferedReader(new InputStreamReader(ClientSocket.getInputStream()));
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: hostname");
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: hostname");
        }

    if (ClientSocket != null &&  inchar != null && bufferchar != null) {
            try {

                  inchar.write("HELO\n");
                  inchar.write("Hi there\n");
                  inchar.write("\n.\n");
                  inchar.write("QUIT");

                String responseLine;
                while ((responseLine = bufferchar.readLine()) != null) {
                    System.out.println("Server: " + responseLine);
                    if (responseLine.indexOf("Ok") != -1) {
                      break;
                    }
                }
// clean up:
// close the output stream
// close the input stream
// close the socket
                inchar.flush();
                
                inchar.close();
                bufferchar.close();
               ClientSocket.close();
            } catch (UnknownHostException e) {
                System.err.println("Trying to connect to unknown host: " + e);
            } catch (IOException e) {
                System.err.println("IOException:  " + e);
            }
        }
    }

}

I change the code and it does not print anything.

reads the Line from the stream and then prints it on the standard output. If the line contains "Ok" it breaks out of the loop.

But I don't see any sentence in that code that contains "OK".You can check original site:
http://www.javaworld.com/jw-12-1996/jw-12-sockets.html?page=3

[Ulf Dittmer]

Why are you ignoring my posts? As long as your socket code calls "readLine" or "println" it's liable not to work correctly (or not at all).

[abalfazl hossein]

Sometimes this program does't work and folks told me it is about firewall or maybe my computer is behind a NAT

Then how other programs access to internet without any problem?If it is a permission, I can give permission and it isn't necessery to turn off firewall.

[Henry Wong]

abalfazl hossein wrote:
Sometimes this program does't work and folks told me it is about firewall or maybe my computer is behind a NAT

Then how other programs access to internet without any problem?If it is a permission, I can give permission and it isn't necessery to turn off firewall.

Well, if you are behind a NAT server, you should have no problems accessing the internet. A NAT hides you from the internet, it doesn't hide the internet from you.

If you want a machine on the internet to get you a NAT'ed machine, you will need to configure the server to forward ports to your machine.

Henry

[abalfazl hossein]

Thanks Sir,

If you want a machine on the internet to get you a NAT'ed machine, you will need to configure the server to forward ports to your machine.

May you explain more?

[Stephan van Hulst]

Well, your clients need to use some sort of IP address and port to make contact with your server. If your server is in a LAN, it has a local IP address which is not visible to your clients. What you need to do is configure your router (which has an IP address that *is* visible to your clients) to forward any packets it receives on a specific port to your server.

[abalfazl hossein]

Thanks, But MSN messenger, Or Yahoo messenger doesn't manipulate the router.

[Joe Ess]

I posted about port forwarding in this thread three weeks ago (see my post of Thursday, December 30, 2010 08:05:57). It looks like you're chasing your tail at this point.

[Rob Spoor]

abalfazl hossein wrote:Thanks, But MSN messenger, Or Yahoo messenger doesn't manipulate the router.

That's because they're clients, not servers. They initiate the connection instead of listening for incoming connections.

[Henry Wong]

abalfazl hossein wrote:Thanks, But MSN messenger, Or Yahoo messenger doesn't manipulate the router.

Actually it does, but something tells me that it would be a good idea to understand what was discussed already first.

Henry