Write a connection oriented socket program which can exchange the message between server and client once the connection is established.

  Here's an example of a connection-oriented socket program in Java that establishes a connection between a server and a client and allows them to exchange messages:

Server Code:

import java.io.*;
import java.net.*;
public class Server {
    public static void main(String[] args) throws IOException {

        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(5000);
        } catch (IOException e) {
            System.err.println("Could not listen on port: 5000.");
            System.exit(1);
        }

        Socket clientSocket = null;

        try {
            System.out.println("Waiting for client to connect...");
            clientSocket = serverSocket.accept();
        } catch (IOException e) {
            System.err.println("Accept failed.");
            System.exit(1);
        }

        PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

      BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
     

        String inputLine, outputLine;

        while ((inputLine = in.readLine()) != null) {
            System.out.println("Client: " + inputLine);
            outputLine = "Server: " + inputLine;
            out.println(outputLine);
            if (outputLine.equals("Server: Bye"))
                break;
        }

        out.close();
        in.close();
        clientSocket.close();
        serverSocket.close();
    }
}

Client Code:

import java.io.*;
import java.net.*;
public class Client {
    public static void main(String[] args) throws IOException {

        Socket socket = null;
        PrintWriter out = null;
        BufferedReader in = null;

        try {
            socket = new Socket("localhost", 5000);
            out = new PrintWriter(socket.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: localhost.");
            System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: localhost.");
            System.exit(1);
        }

        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
        String userInput;

        while ((userInput = stdIn.readLine()) != null) {
            out.println(userInput);
            System.out.println("Server: " + in.readLine());
            if (userInput.equals("Bye"))
                break;
        }

        out.close();
        in.close();
        stdIn.close();
        socket.close();
    }
}

To use this program, first run the server code in one terminal window:

$ javac Server.java
$ java Server

Then run the client code in another terminal window:

$ javac Client.java
$ java Client

Once the client connects to the server, they can exchange messages. Any message typed by the client will be sent to the server, which will respond by sending back the same message with "Server:" added to the beginning. The client will display the server's response on the console. If the client types "Bye", the connection will be closed.