Talks about how Node.js and Socket.io are changing the way how Realtime apps are being developed today .

1. Node.js ,
Socket.io
and
the Magic
Bhagaban Behera

3. What is Node.js ?
Created by Ryan Dahl ( Joyent )
Command line tool to run Javascript
Built on Top of Google’s V8 Javascript Engine
Provides Javascript API for Network and File System . Used to
create Servers, Networking tools.
Event-driven , non-blocking I/O APIs
Core written in C/C++ . Supports C/C++ addons.
Can handle thousands of concurrent connections with minimal
overhead on a single process.

4. What’s the need ?

5. Node.js - Features
Really Lean( 8000 lines of C/C++
and 2000 lines of JS )
Exceptionally Fast
Easily Scalable

6. Event-Driven Approach
Analogy – Bank Reception
Analogy - Restaurant

7. The Cost of IO
Accessing RAM ~250 CPU cycles
Disk Operations ~41 000 000 CPU cycles
Reading a file
Writing to a file
Network IO ~240 000 000 CPU cycles
Database Query
HTTP Responses

10. Handling I/O
Apache is multithreaded (depending on
conf.)
Spawns a thread per request (or
process)
Each request is in its own "box”
Blocking IO
result = query('SELECT * FROM ...');
print result.id;

11. The Node way
Single thread for your code
...but, I/O runs in parallel
Handle thousands of concurrent connections
with a single process
Need to be very careful with CPU-intensive
code

12. Why JavaScript ?
• Single Threaded , Asynchronous
• Non blocking IO
• Ubiquitous
• Massive codebase of libraries
• One language to rule them all( Full
stack )

13. Hello World !
HellowWorld.js HellowWorld.php
setTimeout(function(){ echo(“Hello”);
console.log(“World”); sleep(2000);
},2000); echo(“World”);
console.log(“Hello”);

15. Our own HTTP Server
var http= require('http');
var s = http.createServer(function(req,res){
res.writeHead(200,{'content-type' : 'text/plain'}) ;
res.end("hello world n");
})
s.listen(8000);

16. Built-in Modules
• File System
require('fs');
• HTTP Client and Server
require('http');
• TCP Sockets
require('net');
• Many more: http://nodejs.org/docs/v0.4.8/api/

17. Express makes HTTP easier
• Node's HTTP module is low level.
• Express is a simple framework inspired by Sinatra
(Ruby).
• InstallingExpress:
npm install express
• Robust verb-based routing
app.get('/about', function(req, res) { });
• Templating(with Jade or EJS)
• Sessions

18. When to use Node.js ?
Realtime Apps
Crawlers
Single-page Apps
Streaming
File uploading
Online Gaming
Collaboration
Live Sports
Live chat
Financial Applications

19. Getting Started
Node.js: http://nodejs.org/#download
Buildinstructions: http://bit.ly/egLfzu Mac:
brew update && brew install node
npm, a package manager for Node:
curl http://npmjs.org/install.sh | sh
Many modules at: http://search.npmjs.org/
Windows support isn't great.

20. Node PAAS
NodeJitsu
Nodester
Joyent
Heroku

21. Socket.io

22. Real-time Web

23. History
Static Apps
Dynamic Apps
Ajax Apps
Real-time Apps

24. HTTP

25. Ajax Polling

26. Long Polling

27. Sockets

29. Websockets / Socket.io
Socket.IO aims to make realtime apps possible in every
browser and mobile device, blurring the differences between the
different transport mechanisms. It's care-free realtime 100% in
JavaScript.

30. Show me the code
Visit http://socket.io/#how-to-use for excellent and
simple documentation .

31. Contact me !
bhagaban@noisestreet.com / @bhoga