Into to Node.js: Building Fast, Scaleable Network Applications

Node.js
“This is the node.js project: to provide a purely
evented non-blocking infrastructure to script highly
concurrent programs.” - Ryan Dahl
by Shelly Seroussi & Hannah Kim

Node.js is...
● Builds fast, scalable network applications.
● Wrapper to Google’s V8 Javascript runtime.
● Event driven with nonblocking libraries.

contents = File.read(‘/etc/hosts’)
puts “#{contents}”
puts ‘Hello Flatiron’
fs.readFile(‘/etc/hosts’, function(err, contents){
console.log(contents);
});
console.log(‘Hello Flatiron’);
Blocking Code - Ruby
Non-Blocking Code - Node.js
Blocking Code
Non-Blocking Code

Listening
For Events
Known EventsEvent Queue
close
connection
request
connection
close
The Event Loop

Express
● Middleware Using Connect
● URLs Routing as Callbacks
● Redirection Helpers
● File Uploads
● Environment Based Configuration

Socket.io
● Real-time Event-based Communication
● Abstracts Websockets
● Browser Compatibility

Server.js
var express = require('express');
var socket = require('socket.io');
var app = express();
// LISTEN FOR REQUESTS
var server = app.listen(3000);
var io = socket.listen(server);
-----
// ROUTES
app.get('/', function(req, res){
res.render('index', {
title: 'title'
});
});

// Initialize Socket.io
var socket = io.connect('/');
socket.on('user:connect', function(user_count) {
update_user_count( user_count );
});
socket.on('user:disconnect', function(user_count) {
update_user_count( user_count );
});
var active_users = 0;
io.sockets.on('connection', function (socket) {
active_users++
io.sockets.emit('user:connect', active_users);
socket.on('disconnect', function () {
active_users--
io.sockets.emit('user:disconnect', active_users);
});
server.js
index.html

// EVENT: User is drawing something
socket.on('draw:progress', function( user, data ) {
progress_external_path( JSON.parse( data ), user );
}
});
// EVENT: User stops drawing something
socket.on('draw:end', function( user, data ) {
end_external_path( JSON.parse( data ), user );
});
// EVENT: User is drawing something
socket.on('draw:progress', function (uid, coordinates) {
io.sockets.emit('draw:progress', uid, coordinates)
});
// EVENT: User stops drawing something
socket.on('draw:end', function (uid, coordinates) {
io.sockets.emit('draw:end', uid, coordinates)
});
index.html
server.js

Node is great for
● Websocket Servers
● Fast File Upload Clients
● Ad Servers
● Real-Time Data Apps

Contact Us
Shelly Seroussi
shelly.seroussi@flatironschool.com
Hannah Kim
hannah.kim@flatironschool.com

var http = require(‘http’);
http.createServer(function(request, response) {
response.writeHead(200);
response.write(‘Hello, Flatiron School!’);
response.end();
}).listen(3000);
console.log(‘Listening on port 3000’);
Hello Flatiron!

package.json
---
"scripts": {
"start": "app.js"
},
"version": "0.0.0-14",
"engines": {
"node": "0.6.x"
},
"dependencies": {
"express": "^3.5.3",
"jade": "*",
"socket.io": "*"
}
}
{
"name": "drawstuff",
"subdomain": "drawstuff",
"scripts": {
"start": "server.js"
},
"version": "0.0.0-14",
"engines": {
"node": "0.6.x"
},
"dependencies": {
"express": "^3.5.3",
"jade": "*",
"socket.io": "*"
}
}

function onMouseDown(event) {
var point = event.point;
path = new Path();
path.fillColor = active_color_rgb;
path.add(event.point);
// The data we will send every 100ms on mouse drag
path_to_send = {
rgba : active_color_json,
start : event.point,
path : []
};
}
index.html

Paper.js
● Vector Graphic Library Framework
● Runs on Top of HTML5 Canvas

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Node Package Management

Into to Node.js: Building Fast, Scaleable Network Applications

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