public ClientThread(Socket socket, History history, Users users) throws IOException {

    logger.warn("New client is trying to connect to the chat...");
    logger.info("Assigning a socket to a new client...");
    this.s = socket;

    logger.info("Getting the input stream...");
    in = new DataInputStream(s.getInputStream());

    logger.info("Getting the output stream...");
    out = new DataOutputStream(s.getOutputStream());

    this.users = users;
    users.addObserver(this);

    this.history = history;

    start();
    logger.warn("Connection with new user is established.");
  }