[4613] in java-interest

home	help	back	first	fref	pref	prev	next	nref	lref	last	post

Help needed with UDP-client & server

daemon@ATHENA.MIT.EDU (Tim Moons)
Tue Jan 9 14:08:39 1996

Date: Tue, 09 Jan 1996 17:17:28 +0000
From: Tim Moons <tim@innet.be>
To: java-interest@java.Eng.Sun.COM

This is a multi-part message in MIME format.

-----------------------------73382773518973
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Hello all,

I'm programming for a long time Java now.
I try to write a client and a server. NOT in TCP, but UDP.
The SOURCE-codes are ATTACHED. 
The client and server are compiling correcly, but there is an endless 
loop in my server.

The prob :
I start my server, which constantly looks to port 7000. If the client is 
started, he sends an UDP-Packet to port 7000. At the time this packet is 
sent, the server starts in an endless loop. This means that there is a 
connection between the client and the server, but something goes wrong, 
can someone tell me what ?????

	Tim Moons...............

Thanks to everybody who can help me !!!!

-----------------------------73382773518973
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline; filename="UDPSer.java"

// THIS IS THE SERVER !!!!!
// IT IS AN APPLICATION (STAND-ALONE PROGRAM)
// COMPILE IT AND RUN IT LIKE : 'java UDPServer'

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

class Server extends Thread {
  DatagramSocket server;

  byte ibuf[];

  int iPort=7000;

  public static String response, responseUpper;

  public void run() {
   DatagramPacket receive_Packet;
   int ilength=256, i;

   boolean loop=true;
   while (loop) {
     try {
       try {
         StringBuffer s=new StringBuffer();
   
         receive_Packet = new DatagramPacket(ibuf, ilength);
         server.receive(receive_Packet);

         for (i=0 ; i<ilength ; i++) {
           char c=(char)ibuf[i];
           if (i<ilength-1) s.append(c);
         }
 
         response=s.toString();
         responseUpper=response.toUpperCase();

       }
       catch (IOException e) {
         System.out.println("an IO exception occurred: " + e.getMessage());
         e.printStackTrace();
       }

       System.out.println("De server heeft ontvangen : " + response);
       System.out.println("De server heeft dit gecodeerd als : " + responseUpper + " en naar de client gestuurd");
     
     }
     catch (Exception e) {
       System.out.println("an IO exception occurred: " + e.getMessage());
       e.printStackTrace();

       loop=false;
       return;
     }
   }
   stop();
  }

  public void acceptRequests() {
    try {
      server=new DatagramSocket(iPort);
      while (true) {
        System.out.println("Accept");
        run();
      }
    }
    catch (Exception e) {
      System.out.println("exception from Socket server " + iPort);
      return;
    }
  }
}

public class UDPServer {
  public static void main(String args[]) {
    Server testserver;
    testserver=new Server();
    testserver.acceptRequests();
  }
}


-----------------------------73382773518973
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline; filename="UDPCli.java"

// THIS IS THE CLIENT !!!!!
// IT IS AN APPLET (RUN IT IN THE APPLETVIEWER)
// COMPILE IT AND RUN IT LIKE : 'appletviewer ?????.html'

import java.io.*;
import java.lang.*;
import java.net.*;
import java.awt.*;

public class UDPClient extends java.applet.Applet {
  int iport = 7000;
  InetAddress iaddr;

  public static String response;

  DatagramSocket client;

  public void connect() {
    try {
      client = new DatagramSocket(iport);
    } 
    catch (Exception e) {
      System.out.println("an IO exception occurred: " + e.getMessage());
      e.printStackTrace();
    }
  }

  public void sendString(String s) {
    int ilength, j;
    byte ibuf[];
    DatagramPacket sent_Packet;

    ilength = s.length();
    ibuf = new byte[ilength+1];

    for (j=0 ; j<ilength ; j++) {
      ibuf[j] = (byte)s.charAt(j);
    }
    ibuf[ilength] = (byte)'\n';

    try {
      sent_Packet = new DatagramPacket(ibuf, ilength, iaddr.getByName("194.7.1.41"), iport);
      client.send(sent_Packet);
    } 
    catch (Exception e) {
      System.out.println("an IO exception occurred: " + e.getMessage());
      e.printStackTrace();
    }
  }

  public void close_connection() {
    System.out.println("The inputstream is closed !");
    
    try {
      sendString("gedaan");
      client.close();
    }
    catch (Exception e) {
      System.out.println("an IO exception occurred: " + e.getMessage());
      e.printStackTrace();
    }
  }
  

  public void init() {
    resize(400,100);
    UDPClient t;
    t=new UDPClient();

    t.connect();
    t.sendString(new String("Hallo, deze tekst beweegt tussen client en server !!!!!"));
    t.close_connection();

    repaint();
  }

  public void paint (Graphics g) {
    g.drawString("De client kreeg van de server terug", 10,30);
  }
}

-----------------------------73382773518973--

-
This message was sent to the java-interest mailing list
Info: send 'help' to java-interest-request@java.sun.com

home	help	back	first	fref	pref	prev	next	nref	lref	last	post