Develop Simple Application for Request and Response between Client and Server using Socket Programming

Answer :

1. Server Application (Server.java): This will accept client requests, process them, and send a response back to the client.
2. Client Application (Client.java): This will send requests to the server and receive responses.

Here’s how to implement it:

Server.java

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

public class Server {
    public static void main(String[] args) {
        try {
            // Create server socket on port 12345
            ServerSocket serverSocket = new ServerSocket(12345);
            System.out.println("Server is waiting for client requests...");

            // Wait for client connection
            Socket clientSocket = serverSocket.accept();
            System.out.println("Client connected!");

            // Get input and output streams
            InputStream inputStream = clientSocket.getInputStream();
            OutputStream outputStream = clientSocket.getOutputStream();

            // Create buffered reader and writer for reading and sending data
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            PrintWriter writer = new PrintWriter(outputStream, true);

            // Read request from client
            String clientMessage = reader.readLine();
            System.out.println("Received from client: " + clientMessage);

            // Process the request and send a response
            String response = "Hello from Server: You said, '" + clientMessage + "'";
            writer.println(response);
            System.out.println("Response sent to client: " + response);

            // Close the streams and socket
            reader.close();
            writer.close();
            clientSocket.close();
            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Client.java

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

public class Client {
    public static void main(String[] args) {
        try {
            // Connect to the server at localhost and port 12345
            Socket socket = new Socket("localhost", 12345);
            System.out.println("Connected to server!");

            // Create input and output streams
            InputStream inputStream = socket.getInputStream();
            OutputStream outputStream = socket.getOutputStream();

            // Create buffered reader and writer for reading and sending data
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            PrintWriter writer = new PrintWriter(outputStream, true);

            // Send request to server
            String message = "Hello Server!";
            writer.println(message);
            System.out.println("Sent to server: " + message);

            // Read response from server
            String serverResponse = reader.readLine();
            System.out.println("Received from server: " + serverResponse);

            // Close the streams and socket
            reader.close();
            writer.close();
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Steps for Running the Application:

1. Start the Server:
   • Open a terminal or command prompt.
   • Navigate to the directory containing Server.java.
   • Compile and run the server: javac Server.java java Server
   • The server will now be listening for client connections on port 12345.
2. Start the Client:
   • Open another terminal or command prompt.
   • Navigate to the directory containing Client.java.
   • Compile and run the client: javac Client.java java Client
   • The client will connect to the server, send a message, and receive a response.

Notes:

• Server: The Server listens on port 12345 for incoming client connections using ServerSocket. When a client connects, it creates a Socket to communicate with that client. It reads the message sent by the client and sends a response back.
• Client: The Client connects to the server at localhost and port 12345. It sends a request and waits for the server’s response.