Socket Programming using UDP Socket

Socket:

Sockets allow communication between two different processes on the same or different machines. A Unix Socket is used in a client-server application framework. A server is a process that performs some functions on request from a client. The client in socket programming must know two information:

• IP Address of Server, and
• Port number.

Java DatagramSocket class:

Java DatagramSocket class represents a connection-less socket for sending and receiving datagram packets.

A datagram is basically an information but there is no guarantee of its content, arrival or arrival time.

Commonly used Constructors of DatagramSocket class:

• DatagramSocket() throws SocketEeption: it creates a datagram socket and binds it with the available Port Number on the localhost machine.
• DatagramSocket(int port) throws SocketEeption: it creates a datagram socket and binds it with the given Port Number.
• DatagramSocket(int port, InetAddress address) throws SocketEeption: it creates a datagram socket and binds it with the specified port number and host address.

Java Program for Server side using UDP:

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.SocketException;

public class udpBaseServer_2 {

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

                        DatagramSocket ds = new DatagramSocket(1234);

                        byte[] receive = new byte[65535];

                        DatagramPacket DpReceive = null;

                        while (true) {

                                    DpReceive = new DatagramPacket(receive, receive.length);

                                    ds.receive(DpReceive);

                                    System.out.println("Client:-" + data(receive));

                                    if (data(receive).toString().equals("bye")) {

                                                System.out.println("Client sent bye.....EXITING");

                                                break;

                                    }

                                    receive = new byte[65535];

                        }

            }

            public static StringBuilder data(byte[] a) {

                        if (a == null)

                                    return null;

                        StringBuilder ret = new StringBuilder();

                        int i = 0;

                        while (a[i] != 0) {

                                    ret.append((char) a[i]);

                                    i++;

                        }

                        return ret;

            }

}

Java Program for Client side using UDP:

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.util.Scanner;

public class udpBaseClient_2 {

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

                        Scanner sc = new Scanner(System.in);

                        DatagramSocket ds = new DatagramSocket();

                        InetAddress ip = InetAddress.getLocalHost();

                        byte buf[] = null;

                        while (true) {

                                    String inp = sc.nextLine();

                                    buf = inp.getBytes();

                                    DatagramPacket DpSend =

                                                new DatagramPacket(buf, buf.length, ip, 1234);

                                    ds.send(DpSend);

                                    if (inp.equals("bye"))

                                                break;

                        }

            }

}

Snapshots:

                        Client                                                                                      Server