A slightly advanced introduction to node.js

An Introduction to Node.JS
Sudar Muthu (@sudarmuthu)
Research Engineer
Yahoo Labs
http://sudarmuthu.com

Agenda
What Node.JS is
What Node.JS is not
Why Node.JS?
Using Node.JS
As a interactive shell
As a Server
As a Client
Common Modules
Terminologies
Questions

What is Node.JS
Provides Evented, non-blocking I/O
Built on Google’s V8
JavaScript Programming Environment
Supports C/C++ based addons
Supports CommonJS Module format
Is fast .. infact very fast.

What is Node.JS
Similar to
EventMachine in Ruby
Twisted in Python
But provides Evented IO as part of the language construct itself and not as a library.

Node.JS is not …
Ruby on Rails
Django
Codeigniter
Node.JS is bare bone and the community are making stuff like Express, connect etc.

Why Node.JS?
Code like this
var result = db.query("select..");
// use result
either blocks the entire process or
implies multiple execution stacks (threads).

Why Node.JS?
But a line of code like this
db.query("select..", function (result) {
// use result
});
allows the program to return to the
event loop immediately. No more
unnecessary threads.

Demo of Callback
// execute the callback after 2 seconds
setTimeout(function () {
console.log("World!");
}, 2000);
// print in console
console.log("Hello");
https://github.com/sudar/jsfoo/blob/master/callback.js

Using Node.JS
Install Node.JS
Install NPM
Install other modules you want by doing
npm install <module_name>
You are good to go

Node.JS – as an interactive shell
Similar to Python’s shell
$> node
> 3 + 1
4
> true != false
true
>.help
>.exit

Node.JS – As a server
var http = require('http'); // require the http module
// create a server
http.createServer(function (req, res) {
// call this function when a request is received
res.writeHead(200, {
'Content-Type': 'text/plain'
});
// send this as part of the response
res.end('Hello Worldn');
}).listen(1337, "127.0.0.1"); // listen on port 1337
// debug information
console.log('Server running at http://127.0.0.1:1337/');
https://github.com/sudar/jsfoo/blob/master/http-server.js

Node.JS – As a client
var http = require('http'); // require the needed modules
// make the request object
var request = http.request({
'host': 'sudarmuthu.com',
'port': 80,
'path': '/',
'method': 'GET'
});
// assign callbacks
request.on('response', function (response) {
console.log('Response Status Code: ' + response.statusCode);
response.on('data', function (data) {
console.log('Body: ' + data);
});
});
https://github.com/sudar/jsfoo/blob/master/http-client.js

Core Modules
Processes
Filesystem
Networking
Utilities
The entire list can be found at http://nodejs.org/docs/v0.4.12/api/

Core Modules - Processes
Node allows you to analyze your process and manage external process
Available Modules
process
child_process
Code samples: http://github.com/sudar/jsfoo/process.js

Core Modules - Filesystem
Low level API to manipulate files
Available Modules
fs
path
Code Samples: http://github.com/sudar/jsfoo/filesystem.js

Core Modules - Networking
Available Modules
net
dgram
http
tls
https
dns
Code Samples: https://github.com/sudar/jsfoo/blob/master/dns.js

Core Modules - Utilities
Provides utility methods
Available Modules
console
util
Code Samples: https://github.com/sudar/jsfoo/blob/master/console.js

Node.JS is useful for..
Writing highly concurrent server applications
Sharing application logic between server and client
Peer-to-peer web applications using websockets

Terminologies
NPM – Package manager (like apt-get)
Modules – Plugins or add-ons for Node.JS
Express – MVC framework (like RoR)
Jade – Template Engine (like Smarty)
Socket.IO – A websockets Library

Links
http://github.com/sudar/jsfoo (all code samples used in this talk)
http://nodejs.org
http://npmjs.org
http://expressjs.com
http://socket.io

Questions
Thank you
Sudar Muthu
http://sudarmuthu.com
http://github.com/sudar
http://twitter.com/sudarmuthu

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A slightly advanced introduction to node.js

by Sudar Muthu

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