Socket Programming in Java: Make changes in the client code, so that the client allows the user to continue to send multiple requests until the user types in Quit. This means that the client process should not exit after the user sends one request and receives one response. Instead, the client process should be able to receive subsequent inputs from the user. You need to have a loop in the client code, so that it can accept the user request until the user explicitly types in Quit. Please comment on what each line does.

You are required to have three files:

The modified UDP client code. (preferred file name: UDPClient.py or UDPClient.java)

The modified TCP client code. (preferred file name: TCPClient.py or TCPClient.java)

The project report, which must include the tests you have run to verify that your code meets the requirements. You can paste what you got in the console or some screenshots.

In this project, you dont need to change anything on the server side. Please run the given code on your machine to understand the code and the original application, before you make changes to the code. Make sure your code works without errors before submission.

The behaviors of the application are as follows:

1. client reads a line of characters (data) from its keyboard and sends data to server.

2. server receives the data and converts characters to uppercase.

3. server sends modified data to client; continue to run to serve other clients.

4. client receives modified data and displays line on its screen and then exits.

We assume that both the client and the server run on the same machine.

Java Socket Programming

If we use UDP sockets, we have the following code:

Java code for the UDP client

import java.io.*;

import java.net.*;

import java.util.Scanner;

public class UDPClient {

private final static int PORT = 5000;

private static final String HOSTNAME = "localhost";

public static void main(String[] args) {

System.out.println("This is the UDP Client.");

try {

DatagramSocket socket = new DatagramSocket(0);

Scanner scanner = new Scanner(System.in);

String requestString = scanner.nextLine();

scanner.close();

byte[] requestBuffer = requestString.getBytes();

InetAddress host = InetAddress.getByName(HOSTNAME);

DatagramPacket request = new DatagramPacket(requestBuffer, requestBuffer.length, host, PORT);

socket.send(request);

DatagramPacket response = new DatagramPacket(new byte[1024], 1024);

socket.receive(response);

String result = new String(response.getData());

System.out.println(result);

} catch (IOException e) {

e.printStackTrace();

}

}

}

Java code for the UDP server

import java.io.*;

import java.net.*;

public class UDPServer {

private final static int PORT = 5000;

public static void main(String[] args) {

System.out.println("This is the UDP Server.");

try {

DatagramSocket socket = new DatagramSocket(PORT);

while (true) {

DatagramPacket request = new DatagramPacket(new byte[1024], 1024);

socket.receive(request);

byte[] requestBuffer = request.getData();

String requestString = new String(requestBuffer);

String responseString = requestString.toUpperCase();

byte[] responseBuffer = responseString.getBytes();

DatagramPacket response = new DatagramPacket(responseBuffer, responseBuffer.length,

request.getAddress(), request.getPort());

socket.send(response);

}

} catch (IOException e) {

e.printStackTrace();

}

}

}

Java code for the TCP client

import java.net.*;

import java.io.*;

import java.util.*;

public class TCPClient {

private static final int PORT = 5000;

private static final String HOSTNAME = "localhost";

public static void main(String[] args) {

try {

Socket socket = null;

try {

socket = new Socket(HOSTNAME, PORT);

} catch (UnknownHostException e) {

e.printStackTrace();

}

System.out.println("Connected.");

DataOutputStream out = new DataOutputStream(socket.getOutputStream());

DataInputStream in = new DataInputStream(socket.getInputStream());

Scanner scanner = new Scanner(System.in);

String line = scanner.nextLine();

out.writeUTF(line);

out.flush();

String response = in.readUTF();

System.out.println(response);

scanner.close();

out.close();

in.close();

socket.close();

} catch(IOException e) {

e.printStackTrace();

}

}

}

Java code for the TCP server

import java.net.*;

import java.io.*;

public class TCPServer {

private static int PORT = 5000;

public static void main(String[] args) {

try {

ServerSocket server = new ServerSocket(PORT);

System.out.println("This is the TCP Server.");

while (true) {

Socket connectionSocket = server.accept();

System.out.println("Client accepted.");

DataInputStream in = new DataInputStream(connectionSocket.getInputStream());

DataOutputStream out = new DataOutputStream(connectionSocket.getOutputStream());

String line = in.readUTF();

String newLine = line.toUpperCase();

out.writeUTF(newLine);

out.flush();

System.out.println("Closing connection.");

connectionSocket.close();

in.close();

out.close();

}

} catch(IOException e) {

e.printStackTrace();

}

}

}