soft-shake.ch - Hands on Node.js

cocktail d’expérience informatiques
Genève 3 & 4 octobre 2011
Seconde édition

Auteur M. LEMEE & R. MATON
Track Incubateur
Session Node.js

Co-founder of Duchess France
http://www.java-freelance.fr
@MathildeLemee

Creator of Web Tambouille
http://www.web-tambouille.fr
@rmat0n

Summary
•  What ? Why ?
•  Non blocking API example
•  Event programming model
•  Express, Socket.IO and modules
•  Mini Hands On
•  Unit Test
•  Limits

What is Node ?

Server-side Javascript

Node.js javascript implementation is V8 Javascript
Engine (Google Chrome)

Provide an easy way to build scalable network programs

Non blocking I/O

Single Threaded

Written by Ryah Dahl

What is Node ?

http://codingrelic.geekhold.com/2010/08/nodejs-from-30000-feet.html

What is Node ?

var http = require('http');

http.createServer(function (request, response) {
res.writeHead(200, {"Content-Type": "text/plain"});
res.end("Hello Worldn");
}).listen(1337, "127.0.0.1");

console.log("Server running at http://127.0.0.1:1337/");

~$ node server.js
~$ curl http://127.0.0.1:1337/

Why using Node ?

•  Ryan Dahl: "Node.js project: To provide a purely evented,
non-blocking infrastructure to script highly concurrent
programs" (http://yuilibrary.com/theater/ryan-dahl/dahl-node/)
•  Scalable software
•  Non blocking I/O
•  Same language and share code between server side and
client side

•  JSON friendly (web, server, database...)

Blocking API example

print("hello");

sleep(2000); blocked!!

print("world");

Non blocking API example

var data = File.read("file.txt");
...
// Here you have to wait... maybe a lot...
...
// And your thread is still alive... doing nothing...
...
parseResult(data);

Non blocking API example

var data = File.read("file.txt", function(data) {
parseResult(data);
});

// Here, your thread is alive and continue working !!!
myOtherCode();

Event programming model

•  Events are the heart of Node.js

•  Everything is event based

•  You can create yours own events

Sample

dummyEmitter.emit('myCustomEvent', 'myValue');

dummyReceiver.on('myCustomEvent', function(data){
console.log(data);
});

Sample
SERVEUR
socket.emit('news', { hello: 'world' });

socket.on('event', function (data) {
console.log(data);
});

CLIENT
socket.on('news', function (data) {
console.log(data);
socket.emit('event', { my: 'data' });
});

Modules

Node Boilerplate

Event Emitter 2

Underscore

Vows

Coffeemate

Node Inspector

Spotify, Twitter, Gravatar, Dropbox, AWS,

https://github.com/joyent/node/wiki/modules

Express
Web Framework

Inspired by Sinatra (Ruby)

Systèmes de templates (jade, Haml, EJS...)

var app = express.createServer();

app.get('/', function(req, res) {
res.send('Hello World');
});

app.listen(3000);

Express
app.configure('development', function() {
server.set('views', __dirname + '/views');
server.set('view engine', 'ejs');
app.use(express.static(__dirname + '/public'));
app.use(express.errorHandler({ dumpExceptions: true,
showStack: true }));
});

app.configure('production', function() {
server.set('views', __dirname + '/views');
server.set('view engine', 'ejs');
var aYear = 31557600000;
app.use(express.static(__dirname + '/public', { 'maxAge': aYear }));
app.use(express.errorHandler());
});

Express
app.get('/user/:id', function(req, res) {
res.send('user' + req.params.id);
});

'/users/:id?'
/users/5
/users

'/user/:id.:format?'
/user/12
/user/12.json

'/user/:id/:operation?'
/user/1
/user/1/edit

'/files/*'
/files/jquery.js
/files/javascripts/jquery.js

Socket.IO - Why ?

WebSocket : Firefox 4, Chrome 4, Opera 10.70, and Safari 5.

Asynchronous communication from client to server.

AJAX - XmlHttpRequest ?

Flash / AJAX Long Polling
Disconnection

Socket.IO - How

var io = require('socket.io').listen(80);

io.sockets.on('connection', function (socket) {
io.sockets.emit('info', 'a player join the game');

socket.on('chat', function (msg) {
console.log('send a chat', msg);
});

socket.on('disconnect', function () {
sockets.emit('user disconnected');
});
});

Socket.IO - How

<script>
var socket = io.connect('http://localhost');

socket.on('connect', function () {
socket.on('info', function (data) {
alert(data);
});
});

socket.emit('chat',myMessage);
</script>

Socket.IO - How
•  custom messages :
socket.emit('my custom event',{data:xxx});
•  volatile :
socket.volatile.emit('tweet',tweet);
•  acknoledgements
•  broadcast :
socket.broadcast.emit('hello','world');
•  room :
socket.join('justin bieber fans')
•  send a message in a room :
io.sockets.in('my room').emit('hello','world');
•  storing data :
socket.set('name','Mathilde',function () { //callback });

Modules

Create yours !

hello.js
var world = function() {
alert("helloworld");
};
exports.world = world;

server.js
var hello = require("./hello")
hello.world();

Mini Hands On

Go Mathilde o/

Tests
MLE
•  Unit tests
o  Node.js provides its own assert module
http://nodejs.org/docs/v0.5.6/api/assert.html

o  QUnit (JQuery) http://docs.jquery.com/Qunit
o  NodeUnit https://github.com/caolan/nodeunit
o  Expresso https://github.com/visionmedia/expresso
•  Integration tests
o  Zombie.js http://zombie.labnotes.org
•  Behavior Driven Development
o  vowsjs http://vowsjs.org/
o  jasmine-node https://github.com/mhevery/jasmine-node

•  https://github.com/joyent/node/wiki/modules#wiki-testing

Unit Tests with QUnit

<script>
$(document)
.ready(
function() {
module("1. Game");
test(
"Connais la valeur du joueur suivant en fonction du joueur actuel",
function() {
game = new Game();
game.take(3);
game.take(1);
equals(game.otherPlayer(), "O", "O est le joueur précédent");
});
...
</script>

Limits

- Cryptic error messages
node.js:50 throw e; ^
Error: ECONNREFUSED, Connection refused at
IOWatcher.callback (net:870:22) at node.js:607:9

client.on("error", function (err) {
console.log("Error " + err);
});

Limits

- Cryptic error messages

- Only one thread (it is also an advantage)
- Can be difficult to read

- Non async lib/third party decrease perfs

- IDE, Tooling, Debugger, Profiler

- How to choose a good module ?

Node REPL

~$ node
> 1+2
3
> [1, 2, 3].splice(1,2)
[2, 3]
> process.pid
2998
> ...

Links

Quick tour : http://www.slideshare.net/the_undefined/nodejs-a-quick-tour

Node + Websockets :
http://www.slideshare.net/the_undefined/nodejs-a-quick-tour

Node beginner : http://nodebeginner.org/

The Node Beginner Book :
https://github.com/ManuelKiessling/NodeBeginnerBook

Hands on Node.js : http://nodetuts.com/handson-nodejs-book.html

Node.js in Action (été 2012): http://www.manning.com/cantelon

soft-shake.ch - Hands on Node.js

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