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JavaScript
IN THE CLOUD

Mostafa Eweda
eSpace Technologies
10 January, 2013
Saturday, February 2, 13

Program

• Javascript, 1995 to 2013
• Building Cloud9
• Demo


Javascript

• Livescript
• Netscape 2.0
• Not like Java
• More like Scheme


JS had to "look like Java" only
less so, [it had to] be
Java's dumb kid brother.


XMLHttpRequest


DOM

• Never meant to be scripted
• Direct mapping of C structures
• Incovenient API


Java vs. Javascript

Let’s confess:
JavaScript is already the language of the Web

People started to care

• VMs got faster
• And embeddable!
• EcmaScript 5
• JSConf

So, JavaScript is a very simple, but often
misunderstood language.

Node.js is a NOT another web
framework. I promise !

Google’s V8 engine
as an executable!


LibUV


Asynchronous is cool!


I hate
asynchronous!


Normal C++ IO


LibUV C++ IO


Javascript LibUV

Node.js is a platform for building fast,
scalable network applications.

Javascript bindings to LibUV

Standard libraries in JS

JS executed in V8


LibUV
Not exclusive


Read File in Ruby
file = File.new("readfile.rb", "r")
while (line = file.gets)
# Do something with line
end
file.close

Read File in Node
fs.readFile('readfile.js', function (err, buffer){
if (err) throw err;
// File is read and we're done.
});


browser.js

db.js

server.js


Normal C++ IO
• Node.js is fast by design.
• Never blocking on I/O means less
threads.


Program

Async.parallel([
function loadData(next) {
db.loadData(next);
},
function readFile(next) {
fs.readFile(fName, next);
], function done(err, items) {
if (err) throw err;
// Do something with items
});

https://github.com/caolan/async

Program
var user;
Async.series([
function loadUser(next) {
db.getUser(user_id, function(err, u){
user = u;
next(err);
});
},
function findItems(next) {
var sql = "SELECT * FROM store WHERE
type=?";
db.query(sql, user.type, next);
], function done(err, items) {
if (err) throw err;
// Do something with items
});


Program
Mix to do complex stuff like:

https://github.com/caolan/async

Normal developers


JavaScript Developer


is to

as is to


You really need HELP

Text



Text

undeclared variable



Text

undeclared variable

Iterating using undeclared variable
Did you mean “length”?



Text

undeclared variable

Iterating using undeclared variable
Did you mean “length”?
function created in loop
Warning: you are in an anonymous inner function with its own “this” pointer


Debugging


(Smart!) Code completion


Free Linux VM!

Real terminal

Collaboration


Create

Deploy
Run/Debug

Share Test


Program

• Javascript, 1995 to 2012
• Building Cloud9
• Demo


Node.js simple server

var http = require('http');

http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello world');
}).listen(3000);


Node.js real web app
express / connect
$ npm install -g express
$ express --sessions --css stylus --ejs jade
$ cd myapp
$ npm install
$ node app.js

app.get('/hello.txt', function(req, res){
res.send('Hello World');
});
app.listen(3000);
console.log('Listening on port 3000');

$ node app

http://expressjs.com/

Node.js real web app
Socket.IO 100% JS
Realtime apps made possible blurring the
differences between browser transport mechanisms.

$ npm install socket.io

Server Client
var io = require('socket.io'); <script src=/slideshow/javascript-in-the-cloud/16306312/"/socket.io/socket.io.js"></script>
// attached to the express app <script>
// or runs standalone on port 80 var socket = io.connect('http://localhost');
io = io.listen(app || 80);
socket.on('message', function (msg) {
io.sockets.on('connection', function (socket) { console.log(msg);
socket.on('message', function (msg) { socket.send({ info: 'trash' });
console.log(msg); });
}); </script>
});

http://socket.io

Future (Architect)
• A simple yet powerful plugin system for
large-scale Node.js applications
• Dependency Injection for JavaScript
Managing > ~100K LOC of JS
JS: Dynamically typed - Singly threaded

http://github.com/c9/architect

Wrap-Up

• Node.js is brilliant for modern web apps
• If you do realtime app that is meant to be scalable,
you should probably consider Node.js & Socket.io

• Scale your code base: http://github.com/c9/architect
for your application.

• Check out c9.io for a serious online IDE.


Text

http://c9.io

Mostafa Eweda
github.com/mostafaeweda
@mostafaeweda


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