Node azure

AZ02 – NODE.JS SU WINDOWS AZURE

Emanuele DelBono
Software engineer
@emadb

#CDays13 – 27 e 28 febbraio 2013

Do you really know
javascript?

> Array(10)
[ , , , , , , , , , , ]

> Array(10)
[ , , , , , , , , , , ]
> Array(10).join('yo')

> Array(10)
[ , , , , , , , , , , ]
yoyoyoyoyoyoyoyoyoyoyo

> Array(10)
[ , , , , , , , , , , ]
> Array(10).join('yo' + 1)

> Array(10)
[ , , , , , , , , , , ]
yo1yo1yo1yo1yo1yo1yo1yo1yo1yo1yo

> Array(10)
[ , , , , , , , , , , ]
> Array(10).join('yo' - 1) + ' Batmaaan'

> Array(10)
[ , , , , , , , , , , ]
> Array(10).join('yo' - 1) + ' Batmaaan'

NaNNaNNaNNaNNaNNaNNaNNaNNaNNaN Batmaaan

Agenda
• What is node.js?
• Architecture
• Installation
• Building applications
• Modules

I am…
Software engineer and
•
Architect in codiceplastico.
Writes web apps in C#,
javascript e ruby.

What is node.js?
• A development framework that uses
event driven, non blocking I/O
• Built on javascript
• Based on Google V8 engine
• Ideal for high performance

History
• Created by Ryan Dahl in 2009
• He is trying to ﬁnd the best way
to notify the user in real time
• Written in C
• https://github.com/joyent/node

Curious facts
• It’s one of the most watched project on
Github
• The community has build more than 21k
modules
• It’s not only for web apps

Web apps scalability
• Synchronous:
– Every request could block the others
• Multithread
– Hard times with thousands connections

Node keep it simple

Single thread

Non-blocking
• Blocking
var result = db.query(‘select ...’)

• Non blocking
db.query(‘select...’,function(result) {...})

Why didn’t I think at it before?
• Culture: The non blocking code seems
more difﬁcult to get
• Infrastructure: single threaded event loop
require non-blocking I/O

The event loop
• Every operation must be non-
blocking
• Lots of callbacks
• The result will be available in
one of the next ticks

The event loop
• No code in the main method
• All I/O operations are asynchronous
• Be quick to respond

YOU HAVE TO THINK IN
CALLBACKS

Javascript
• Seems the best choice:
– Anonymous functions, closures
– One callback at a time
– None were using it on the server side

Who are using it?

https://github.com/joyent/node/wiki/Projects,-Applications,-and-Companies-Using-Node

What can you do with node?
Web Server
TCP Server
Robot controller
Command line apps
Proxy server
Streaming server
VoiceMail server
Music machine

What you get?
• node executable
• npm (the node packet manager)
• REPL

IDE
• WebMatrix on windows
• Cloud9
• WebStorm

• Don’t forget about the command line + text
editor

Not only for web apps
• Useful for I/O intensive tasks
• Scripts for DevOps
• Build (jake)

• Not suitable for intensive CPU tasks

Modules (npm)
• NPM is the Nuget for noders
• No version clash
• package.json to manage app
dependencies

Express.js
• Minimal MVC framework
• Verb oriented
• Middleware
• Templating

Express.js
var express = require('express');
var app = express();

app.get('/', function(req, res){
res.send('hello noders');
});

app.listen(3000);

Jade
doctype 5
html(lang="en")
head
title= pageTitle
script(type='text/javascript')
if (foo) {
bar()
}
body
h1 Jade - node template engine
#container
if youAreUsingJade
p You are amazing
else
p Get on it!

Azure
• You can deploy your app to Windows
Azure.
• Using the CLI
• From WebMatrix (for IDE addicted)

Node on Azure
• Web sites
• Cloud services
• Virtual machines

Deploy on azure
$ azure site create nodeisfun --git
$ git add .
$ git commit -m’first commit’
$ git push azure master
$ azure site browse

mongodb
var MongoClient = require('mongodb').MongoClient;

MongoClient.connect("mongodb://localhost:27017/myDb",
function(err, db) {

var collection = db.collection('myCollection');

collection.findOne({mykey:1}, function(err, item){
console.log(item)
});
});

node-sqlserver
conn.queryRaw("SELECT * FROM Employees", function (err, res) {
if (err) {
   console.log("Error running query!");
    return;
  }
  for (var i = 0; i < res.rows.length; i++) {
   console.log(res.rows[i][0] + " " + res.rows[i][1]);
  }
});

WebSockets
• Full-duplex communication over TCP
• W3C standard

• The server calls the browser!!

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

io.sockets.on('connection', function (socket) {
socket.emit('news', { hello: 'world' });
socket.on('my other event', function (data) {
console.log(data);
});
});

WebSockets: socket.io
<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect('http://localhost');
socket.on('news', function (data) {
console.log(data);
socket.emit('my other event', { my: 'data' });
});
</script>

DEMO
• A collaborative Drum Machine
– Node.js/express
– Azure
– WebSockets
– Web Audio API

Conclusions
• Node is an interesting platform
• It worth a look
• It’s becoming popular

Not all problems
should be solved in C#

Q&A
Slides and demos available here
http://www.communitydays.it/
http://github.com/emadb/
http://slideshare.net/emadb/

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