import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

/**
* This is the Server program which is responsible for connecting
* different clients together.
*
* This is the first program to run on the host machine.
* Then run the Client program on 4 different machines.
*
* To compile: javac Server.java
* To run: java Server
*
* Port is the port name on which this Server to run e.g. 8888 etc.
*/

class Process extends Thread {

private Socket socket;
private Server server;
private int id;
private PrintWriter printWriter;

public Process(Socket socket, Server server, int id) {
   this.socket = socket;
   this.server = server;
   this.id = id;
}

public int getProcessId() {
   return id;
}

/**
* The method pass message to the client to which
* this process is attached.
* @param message
*/
public void sendMessage(String message, int senderId) {
   try {
         String[] split = message.split(" ");
         if (split.length > 1) {
            String msg = "" + senderId;
            for (int i = 2; i < split.length; i++) {
               msg += " " + split[i];
            }
            printWriter.println(msg);
         } else {

We have stressed the need for an operating system to make efficient...