This blink like it's 1998

what js is good for

if (el.style.visibility === 'hidden') {
  el.style.visibility = 'visible'
} else {
  el.style.visibility = 'hidden'
}

Flow control is built-in

If applications sends too much data, we can slow them down with backpressure!

function process(data, cb) {
  /* oh yeah, we are processing one
     thing at a time
     or we can do batches! */
  setTimeout(cb, 500)
}

Node.js has streams too!

source.pipe(dest).pipe(source)

Microservices

• AWS Lambda
• Netflix
• Uber
• ... and many others!

The best community ever

we love you too, npm

var HelloMessage = React.createClass({
  render: function() {
    return 
Hello {this.props.name}
;
  }
});

ReactDOM.render(<HelloMessage name="John" />, mountNode);

NodeBots

Johnny Five

var five = require("johnny-five")
var board = new five.Board()

board.on('ready', function () {
  /* Create an Led on pin 13 */
  var led = new five.Led(13)
  /* Blink every half second */
  led.blink(500)
})

You should not see this!

Universal JS

• use the same libraries in browsers, servers, and devices
• simple architecture, fewer components
• can we use all of this to build an IoT system?

What is an IoT system?

Architecture

Sensor Data Flow

Commands Flow

Problems

• Latency
• no reuse
• complex
• lots of moving parts

Using a pub/sub broker

Sensor Data Flow

Commands Flow

MQTT.js works on

• browsers
• servers
• devices

MQTT

• publish/subscribe protocol
• multiple quality of service level..
• ..with at-least-once and exactly-once semantics
• low overhead (2 bytes at minimum)
• offline messaging
• retained messages, like a key/value store
• can run over WebSocket

Publish-Subscribe

MQTT broker in Node.js

Mosca

• http://npm.im/mosca
• Standalone usage, through `$ mosca`
• Embeddable in your app, so you can do X for every message
• Authentication APIs
• Supports Mongo, Redis, AMQP, and MQTT as pub/sub backends
• Needs a DB, such as LevelDB, Mongo, or Redis
• Support websockets
• Test instance available at test.mosca.io
• New version coming with 10x throughput improvement

Authentication in Mosca

var server = new mosca.Server(settings);
/* Accepts the connection if the username
   and password are valid */
function authClient(client, user, pass, cb) {
  var authorized = (
    user=== 'alice' &&
    pass.toString() == 'secret' );
  if (authorized) client.user = user;
  callback(null, authorized);
}
server.authenticate = authClient;

Publish Authorization in Mosca

var server = new mosca.Server(settings);
function authPub(client, topic, payload, cb) {
  var ok = client.user == topic.split('/')[1];
  /* we can alter the message here */
  if (ok) callback(null, payload);
  else callback(null, false);
}
server.authorizePublish = authPub;

Subscribe Authorization in Mosca

var server = new mosca.Server(settings);
function authSub(client, topic, cb) {
  var ok = client.user === topic.split('/')[1];
  cb(null, ok);
}
server.authorizeSubscribe = authSub;

Storing data in a timeseries

var server = new mosca.Server(settings);

function published(packet, client, callback) {
  timeseries.store(packet, callback);
}
server.published = published;

http://senecajs.org

var seneca = require('seneca')()
seneca.add({
  role:'user',
  cmd:'login'
}, function (args, callback) {
  var loggedIn = args.username === 'matteo' &&
                 args.password === 'collina'
  callback(null, { loggedIn:loggedIn })
})
seneca.listen()

var seneca = require('seneca')()
var client = seneca.client()
client.act({
  role:'user',
  cmd:'login',
  username: 'matteo',
  password: 'collina'
}, function (err, result) {
  console.log(result.loggedIn)
})

Features

• multiple transports, from bare TCP to busses
• build a monolith, and then split it away
• deep inspection & debugging tools
• authentication/user managament system
• control panel
• integration with HAPI
• gossip-based service discovery

Demo: an IoT system

• microservice based
• on top of MQTT
• service discovery based on gossip

Demo!

https://github.com/nearform/iot-system

Links

• MQTT.js: http://npm.im/mqtt
• Mosca: http://mosca.io
• Seneca: http://senecajs.org/
• Fuge: http://fuge.io
• Vidi: https://github.com/vidi-insights/vidi-dashboard
• seneca-mesh:  http://npm.im/seneca-mesh
• toolbag: http://npm.im/toolbag
• swim-js: http://npm.im/swim-js
• baseswim: http://npm.im/baseswim

This presentation

• https://github.com/mcollina/js-everywhere
• https://mcollina.github.io/js-everywhere
• https://github.com/nearform/iot-system

Thanks!

If you need help with Node

or the Internet of Things

matteo.collina@nearform.com

@matteocollina on Twitter

www.nearform.com