Computer Network Lab Programs

DayTimeClient.java

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


public class lab5DayTimeClient{
    
    public static void main (String args[]) throws Exception {

        Socket soc = new Socket("localhost" , 1300);
        InputStreamReader r = new InputStreamReader (soc.getInputStream());
        BufferedReader br = new BufferedReader (r);
        System.out.println ("Server: "+br.readLine());
        br.close();
        r.close();
        soc.close();

    }

}

DaytimeServer.java

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


public class lab5DaytimeServer{
    
    public static void main (String args[]) throws Exception {

        ServerSocket ss = new ServerSocket (1300);
        System.out.println ("DayTime Server Stated: Listening on port 1300.");
        // 1)As defined in RFC 867
        // 2)Link to RFC https://www.rfc-editor.org/rfc/rfc867
        // 3)For concurrency, we are using threading!
        while(true){
            Socket soc = ss.accept();
            System.out.println ("Got connection: "+soc.toString());
            Runnable runner = new Runnable (){
                @Override
                public void run()  {
                    try {
                        OutputStreamWriter w = new OutputStreamWriter (soc.getOutputStream());
                        w.write ((new Date()).toString());
                        w.flush();
                        w.close();
                        soc.close();
                    }
                    catch (Exception e){
                        System.out.println (e);
                    }
                }
            };
            (new Thread(runner)).start();
        }

    }

}

lab3Client.java

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


public class lab3Client{
    
    public static void main (String args[]) throws Exception {

        Socket soc = new Socket("localhost" , 3141);
        System.out.println ("Got connection: "+soc.toString());
        InputStreamReader r = new InputStreamReader (soc.getInputStream());
        BufferedReader br = new BufferedReader (r);
        System.out.println ("Server: "+br.readLine());
        br.close();
        r.close();
        soc.close();

    }

}

lab3Server.java

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


public class lab3Server{
    
    public static void main (String args[]) throws Exception {

        ServerSocket ss = new ServerSocket (3141);
        System.out.println ("Waiting for connection:");
        Socket soc = ss.accept();
        System.out.println ("Got connection: "+soc.toString());
        OutputStreamWriter w = new OutputStreamWriter (soc.getOutputStream());
        w.write ("Hello, World!");
        w.flush();
        w.close();
        soc.close();

    }

}

lab4_UDP_Echo.java

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


public class lab4_UDP_Echo{
    
    public static void main (String args[]) throws Exception {
        int portTo = Integer.parseInt(args[1]);
        int portFrom = Integer.parseInt(args[0]);
        DatagramSocket s = new DatagramSocket (portFrom);
        String message = "Hello, UDP Server!";
        byte[] messageData = message.getBytes();
        s.send(new DatagramPacket(messageData,messageData.length, InetAddress.getLocalHost(),portTo));
        for (int i=0;i<5;i++){
            s.receive(new DatagramPacket(messageData,messageData.length));
            System.out.println("Echoing "+portTo+" :- "+new String (messageData));
            s.send(new DatagramPacket(messageData,messageData.length, InetAddress.getLocalHost(),portTo));
        }
    }

}

lab5HalfDuplex.java

import java.util.*;
import java.net.*;
import java.io.*;
// usage: java lab5HalfDuplex <portNumber>
// for eg: java lab5HalfDuplex 3141
public class lab5HalfDuplex{
    
    public static void main (String args[]) throws Exception {
        System.out.println ("Is this Server or Client? [S/c]");
        Scanner scn = new Scanner (System.in);
        String input = scn.nextLine();
        Socket s;
        int port = Integer.parseInt(args[0]);
        char ch = input.charAt(0);
        if (ch =='C' || ch == 'c'){
            s = new Socket("localhost",port);
        }
        else {
            ServerSocket ss = new ServerSocket(port);
            s = ss.accept();
        }
        System.out.print ("Enter User Name: ");
        String name = scn.nextLine();
        BufferedReader br = new BufferedReader (new InputStreamReader(s.getInputStream()));
        OutputStreamWriter w = new OutputStreamWriter (s.getOutputStream());
        while (true){
            System.out.print("Enter a message: ");
            String message = scn.nextLine();
            if (message.equalsIgnoreCase("close")) break;
            w.write(name+" : "+message+"\n");
            w.flush();
            System.out.println (br.readLine());
        }
    }

}

lab6FullDuplex.java

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

public class lab6FullDuplex{

    public static void main (String args[]) throws Exception {

        System.out.println ("Is this Server or Client? [S/c]");
        Scanner scn = new Scanner (System.in);
        String input = scn.nextLine();
        Socket s;
        int port = Integer.parseInt(args[0]);
        char ch = input.charAt(0);
        if (ch =='C' || ch == 'c'){
            s = new Socket("localhost",port);
        }
        else {
            ServerSocket ss = new ServerSocket(port);
            s = ss.accept();
        }

        new Thread(new lab6FullDuplex.reader(s)).start();
        new Thread(new lab6FullDuplex.writer(s)).start();
    }

	public static class reader implements Runnable {
		
		public Socket s;
		
		public reader(Socket s){
			this.s = s;
		}
		
		@Override
		public void run () {
            try {
            	InputStreamReader r = new InputStreamReader (s.getInputStream());
            	while (true) {
            		char  dataLine [] = new char [8*1024];
            		if (r.read(dataLine)!=-1) {
            			System.out.println("Receiver: "+new String(dataLine));
            		}
            	}
            }
            catch (Exception e) {
            	System.out.print(e);
            }
		}
		
	}
	
	public static class writer implements Runnable {
		
		public Socket s;
		
		public writer(Socket s){
			this.s = s;
		}
		
		@Override
		public void run () {
			try {
				OutputStreamWriter w = new OutputStreamWriter (s.getOutputStream());
				Scanner scn = new Scanner (System.in);
				while (true) {
					//System.out.print("Sender: ");
					String message = scn.nextLine();
					w.write(message);
					w.flush();
				}
			}
            catch (Exception e) {
            	System.out.println(e);
            }
		}
	}
}