chatServer.js, Annotated - FAR-Lab/Developing-and-Designing-Interactive-Devices GitHub Wiki

var express = require('express'); // web server application, the toolkit that allows node to talk to the internet
var app = express(); // webapp
var http = require('http').Server(app); // connects http library to server
var io = require('socket.io')(http); // connect websocket library to server
var serverPort = 8000;

Variable declaration. Note:

• the invocation of 'express', which is a server application
• the attachment of the http library, which makes it a webserver
• the attachment of the WebSocket library(socket.io), which acts as a real-time communication link between the server and client

app.use(express.static('public')); // find pages in public directory

// start the server and say what port it is on, in this case, 8000, as defined above. [More info on what ports do.](https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers#Well-known_ports)
http.listen(serverPort, function() { // listening for connections
  console.log('listening on *:%s', serverPort); // writes a message to the console
});

Starting the ChatBot Server Starting the webserver telling it to server files found in folder 'public'

// this is the websocket event handler and say if someone connects
// as long as someone is connected, listen for messages
io.on('connect', function(socket) {
  console.log('a new user connected');
  var questionNum = 0; // keep count of question, used for IF condition.
  socket.on('loaded', function(){ // we wait until the client has loaded and contacted us that it is ready to go.

    socket.emit('answer', "Hey, hello I am \"___*-\" a simple chat bot example."); // We start with the introduction;
    setTimeout(timedQuestion, 5000, socket, "What is your name?"); // Wait a moment and respond with a question.

  });
  socket.on('message', (data) => { // If we get a new message from the client we process it;
    console.log(data);
    questionNum = bot(data, socket, questionNum); // run the bot function with the new message
  });
  socket.on('disconnect', function() { // This function  gets called when the browser window gets closed
    console.log('user disconnected');
  });
});

Client connection. This specifies what to do with connections and messages from clients (e.g. you on the web browser!). This section initializes the ChatBot, waits for the load message from the client and handles the incoming and outgoing traffic.

function bot(data,socket,questionNum) {
  var input = data; // This is generally really terrible from a security point of view ToDo avoid code injection
  var answer;
  var question;
  var waitTime;

/// These are the main statements that make up the conversation.
  if (questionNum == 0) {
    answer= 'Hello ' + input + ' :-)';// output response
    waitTime = 5000;
    question = 'How old are you?';			    
  } else if (questionNum == 1) {
    answer= 'Really, ' + input + ' years old? So that means you were born in: ' + (2018-parseInt(input)); // output response
    waitTime = 5000;
    question = 'Where do you live?';	
  } else if (questionNum == 2) {
    answer = 'Cool! I have never been to ' + input+'.';
    waitTime = 5000;
    question = 'Whats your favorite color?';
  } else if (questionNum == 3) {
    answer = 'Ok, ' + input+' it is.';
    socket.emit('changeBG', input.toLowerCase());
    waitTime = 5000;
    question = 'Can you still read the font?';
  } else if (questionNum == 4) {
    if (input.toLowerCase() === 'yes' || input === 1){
      answer = 'Perfect!';
      waitTime = 5000;
      question = 'Whats your favorite place?';
    } else if (input.toLowerCase() === 'no' || input === 0){
      socket.emit('changeFont','white'); // We really should look up the inverse of what we said before.
      answer = 'How about now?'
      question = '';
      waitTime = 0;
      questionNum--; // Here we go back in the question number this can end up in a loop!
    } else {
      question = 'Can you still read the font?'; // load next question
      answer = 'I did not understand you. Could you please answer "yes" or "no"?'
      questionNum--;
      waitTime = 5000;
    }
  // load next question
  } else {
    answer= 'I have nothing more to say!';// output response
    waitTime = 0;
    question = '';
  }


  /// We take the changed data and distribute it to the required objects.
  socket.emit('answer',answer);
  setTimeout(timedQuestion, waitTime,socket,question);
  return (questionNum+1);
}

ChatBot 'decision tree' These are the answers and questions the chatbot will say. The long if and else statement can be easily modified to change the responses. Note:

• questionNum keeps track of where we are in the conversation tree.
• waitTime Sets how long in milliseconds the answer is shown before the server sends the next question.
• answer The 'answer' type message does not enable the input field.
• question poses a question to the user and enables the input field.

function timedQuestion(socket,question) {
  if(question!=''){
    socket.emit('question',question);
  } else {
    //console.log('No Question send!');
  }
}

waiting function Once the time, as set in waitTime, has run out the question is send to the client if the question is not empty.