Question

h. P2PUtil

i. connectForOneMessage:

1. This method will connect to a given server via Socket for a one-time sending of a message to that server and it will return the reply from the server and disconnect.

2. Code for the Socket communication will be reviewed in class.

Provided code:

P2PUtil.java

import java.io.*;

import java.net.InetSocketAddress;

import java.net.Socket;

/**

* This class holds any utility methods needed for P2P networking communication.

*/

public class P2PUtil {

/**

* Allows a one time socket call to a server, gets reply, and then closes connection.

* @param sIP

* @param iPort

* @param sMessage

* @return

*/

public static String connectForOneMessage(String sIP, int iPort, String sMessage) {

#######################

### ADD CODE HERE ###

#######################

}

}

Answer 1

Note: I have added main method in the P2PUtil class to test the code. Also, I have provided the sever program also.

Source code:

Client:

import java.io.*;

import java.net.Socket;

/**

* This class holds any utility methods needed for P2P networking communication.

*/

public class P2PUtil {

/**

* Allows a one time socket call to a server, gets reply, and then closes connection.

* @param sIP

* @param iPort

* @param sMessage

* @return

*/

   public static String connectForOneMessage(String sIP, int iPort, String sMessage) {
       String rMessage = null;
       try{
           //Connecting to the server
           System.out.println("Connecting to " + sIP + " on port " + iPort);
   Socket client = new Socket(sIP, iPort);
     
   //connection established
   System.out.println("Connected to server " + client.getRemoteSocketAddress());
   //Getting output stream
   OutputStream outToServer = client.getOutputStream();
   DataOutputStream out = new DataOutputStream(outToServer);
     
   //sending message to the server
   out.writeUTF(sMessage);
  
   //getting input stream
   InputStream inFromServer = client.getInputStream();
   DataInputStream in = new DataInputStream(inFromServer);
     
   //receiving message from server
   rMessage = in.readUTF();
  
   //closing the connection
   client.close();
       }
       catch (IOException e) {
   e.printStackTrace();
       }
      
       return rMessage;
   }
  
   public static void main(String [] args){      
       String sIP = "192.168.100.8";   //server IP address
       int sPort = 200;   //server port address
       String sMessage = "Hello, I am your client. Please say hello to me.";   //message to the server
      
       //connecting to server
       String retMessage = connectForOneMessage(sIP, sPort, sMessage);
      
       //printing return message from server
       System.out.println("Server Replied: " + retMessage);
   }
}

Server:

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class P2PServer {
   public static void main(String[] args){
       try {
           @SuppressWarnings("resource")
           //creating server socket object
           ServerSocket serverSocket = new ServerSocket(200);
          
           //waiting for a client connection
System.out.println("Waiting for a client request on port " + serverSocket.getLocalPort() + "...");
Socket server = serverSocket.accept();
  
//connected to aclient
System.out.println("Connected to the client" + server.getRemoteSocketAddress());
//input stream object
DataInputStream in = new DataInputStream(server.getInputStream());
  
//printing message from the client
System.out.println("Message from the client: " + in.readUTF());
//output stream object
DataOutputStream out = new DataOutputStream(server.getOutputStream());
  
//sending message to the client
out.writeUTF("Hello. Thank you for connecting.");
  
//closing the connection
server.close();
  
       }
       catch (Exception e) {
e.printStackTrace();
}
   }
}

Code screenshot:

client:

server:

Output:

Client side:

Server side: