This presentation teaches how to make chatbot using Facebook messenger. To build a simple bot that can send simple messages more likely to say echo bot. A bot that will send a message back whatever we send as text format.

1. HOW TO “BUILD A FACEBOOK MESSENGER
BOT” FOR YOUR BUSINESS
By: www.edtechnology.in

2. Objective
• To build a simple bot that can send simple messages more likely
to say echo bot.
• A bot that will send a message back whatever we send as text
format.

3. Procedure
Create Facebook developer App
•https://developers.facebook.com/
Create NodeJs Backend
•Create server.js, config.js, and
API.js file
•Install request and restify two
NPM modules
Create a Facebook Page After that select messenger
product and click setup,
then generate the page
token from there
Messenger Bot ready to
use
1 2 3 4 5

4. Short Tour
1. Create your facebook page, from
your facekook account.
2. Create a facebook developer account.
1
2

5. 3
4
3. Select messenger product and click
setup, then generate the page token
4. Create Node Js Backend.

6. The config.js File
• The file includes general configuration and
tokens so we can use it when it’s required.

7. Code
‘use strict’;
module.exports ={
“FB”: {
“PAGE_ACCESS_TOKEN”:
“page_access_token”,
“VERIFY_TOKEN”:“verify_token”,
“APP_SECRET”:“app_secret”
}
}

8. The API.js File
• The file helps to connect with facebook messenger platform and can send and
receive the messages.
• It consists of the following:
• registerHook() Function will verify the hub challange code when we register our server in facebook.
• incoming() Function is for checking which event we are getting either we are getting text,
attachment or anything else.
• sendMessage() This is for the sending data to the messenger by using Graph API URL.
• txt() function is the common payload template that we will call when we have to send text
message.

9. Code
‘use strict’;
const request = require(‘request’);
class FB{
constructor(config) {
try {
if(!config || config.PAGE_ACCESS_TOKEN ===undefined ||
config.VERIFY_TOKEN === undefined || config.APP_SECRET ===
undefined) { throw new Error(“Unable to access tokens!”);}
else {
this.PAGE_ACCESS_TOKEN=config.PAGE_ACCESS_TOKEN;
this.VERIFY_TOKEN=config.VERIFY_TOKEN;
this.APP_SECRET = config.APP_SECRET;
}
} catch(e) {console.log(e);
}
}
registerHook(req, res) {
let {mode, verify_token, challenge} = req.query.hub;
if(mode === ‘subscribe’ &&verify_token === this.VERIFY_TOKEN) {
return res.end(challenge);
} else {
console.log(“Could not register webhook!”);
return res.status(403).end();
}
}

10. Code
incoming(req, res, cb) {
let data = req.body;
if(data.object === ‘page’) {
data.entry.forEach(pageObj => {
pageObj.messaging.forEach(msgEvnt=> {
let messageObj = {
sender: msgEvent.sender.id,
timeOfMessage:msgEvent.timestamp,
message: msgEvent.message
}
cb(messageObj);
});
});
}
res.send(200);
}
sendMessage(payload) {
return new Promise((resolve, reject) => {
request({
uri:‘https://graph.facebook.com/v2.6/me/messages’,
qs: {
access_token: this.PAGE_ACCESS_TOKEN
},
method: ‘POST’,
json: payload
}, (error, response, body) => {
if(!error && response.statusCode === 200){
resolve({messageId: body.message_id});
} else {reject(error);}
});
});
}

11. Code
txt(id, text, messaging_type = ‘RESPONSE’) {
let obj = {
messaging_type,
recipient: {
id
},
message: {
text
}
}
this.sendMessage(obj)
.catch(error => console.log(error));
}
}
module.exports = FB;

12. The server.js File
• The file helps create a restify server

13. Code
‘use strict’;
const Restify = require(‘restify’);
const server = Restify.createServer({
name: ‘Simplebot’
});
const PORT = process.env.PORT || 3000;
server.use(Restify.jsonp());
server.use(Restify.bodyParser());
const config = require(‘./config’);
const API = require(‘./API’);
const f = new API(config.FB)
server.get(‘/’, (req, res, next) => {
f.registerHook(req, res);
return next();
});
server.post(‘/’, (req, res, next) => {
f.incoming(req, res, msg => {
const {
message,
sender
} = msg;
if(message.text) {
f.txt(sender, `You just said ${message.text}`);
}
});
return next();
});
server.listen(PORT, () => console.log(`running on port ${PORT}`));

14. Establish Connection
• Create two routes one for GET and One For POST.
• To verify request will come from facebook we are calling registerHook() to verify the hub
challenge code.
• Now in Post method we will use incoming() to check did we got the text from the user
and by using txt() function we will send the text message again.
• That’s it in coding part now run your node server and but we need live HTTPS URL rather
than the localhost so Download ngrok and make the port live.
• You will get Two URL and copy HTTPS one.
• In the webhook section of the Facebook app add URL and the verification token that you
declared in config.js.

15. References
http://www.edtechnology.in/machine-learning/how-to-build-a-facebook-messenger-bot-for-your-
business/