1. We need to have a secured connection, this type of direct connection could be a target of DDOS attacks.

2. public class Server {

private static final int PORT = 1000;

public static void main(String[] args) {

   try (
            ServerSocket serverSocket
            = new ServerSocket(PORT);
            //new ServerSocket(Integer.parseInt(args[0]));
            Socket clientSocket = serverSocket.accept();
            PrintWriter out
            = new PrintWriter(clientSocket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(
                     new InputStreamReader(clientSocket.getInputStream()));) {
         String inputLine;
         while ((inputLine = in.readLine()) != null) {
            //out.println(inputLine);
            //System.out.println("" + inputLine);
            //System.out.println(inputLine);
            out.println(process(inputLine));
         }
   } catch (IOException e) {
         System.out.println("Exception caught when trying to listen on port "
               + PORT + " or listening for a connection");
         System.out.println(e.getMessage());
   }
}

private static String process(String input) {
   String feedback = "-0.01:Invalid message";

   try {
         String[] sp = input.split(":");
         if (sp.length != 5) {
            feedback = "-0.01:The message has to follow the right format";
         } else {
            int year = Integer.parseInt(sp[1]);
            int month = Integer.parseInt(sp[2]);
            int day = Integer.parseInt(sp[3]);
            BookingDay bd = new BookingDay(year, month, day);
            if (bd.isValidDate() == false) {

This program counts characters in each line of a text file, and wri...