Présentation de Node.js

Node.js http://nodejs.org

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 );
print( "world" );
blocked!!

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

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

Event programming model Sample
dummyEmitter.emit('myCustomEvent', 'myValue');
dummyReceiver.on('myCustomEvent', function(data){
console.log(data);
});

Event programming model Sample
socket.emit('news', { hello: 'world' });
socket.on('event', function (data) {
console.log(data);
});
SERVEUR 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 var app = express.createServer(); app.get( '/' , function(req, res) { res.send( 'Hello World' ); }); app.listen( 3000 ); Web Framework Inspired by Sinatra (Ruby) Systèmes de templates (jade, Haml, EJS...)

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
Node.js provides its own assert module http://nodejs.org/docs/v0.5.6/api/assert.html
QUnit (JQuery) http://docs.jquery.com/Qunit
NodeUnit https://github.com/caolan/nodeunit
Expresso https://github.com/visionmedia/expresso
Integration tests
Zombie.js http://zombie.labnotes.org
Behavior Driven Development
vowsjs http://vowsjs.org/
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>

Unit Tests with QUnit

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

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Présentation de Node.js

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