An Introduction to Node.JS

Sudar Muthu (@sudarmuthu)Research Engineer

Yahoo Labshttp://sudarmuthu.com

AgendaWhat Node.JS isWhat Node.JS is notWhy Node.JS?Using Node.JS

◦As a interactive shell◦As a Server◦As a Client

Common ModulesTerminologiesQuestions

What is Node.JSProvides Evented, non-blocking

I/OBuilt on Google’s V8JavaScript Programming

EnvironmentSupports C/C++ based addonsSupports CommonJS Module

formatIs fast .. infact very fast.

What is Node.JS

Similar to

EventMachine in RubyTwisted in Python

But provides Evented IO as part of the language construct itself and not as a library.

Node.JS is not …

Ruby on RailsDjango 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 orimplies 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 theevent loop immediately. No moreunnecessary threads.

Demo of Callback// execute the callback after 2 secondssetTimeout(function () { console.log("World!");}, 2000);

// print in consoleconsole.log("Hello");

https://github.com/sudar/jsfoo/blob/master/callback.

js

Using Node.JSInstall Node.JSInstall NPMInstall 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 + 14> true != falsetrue>.help>.exit

Node.JS – As a servervar http = require('http'); // require the http module

// create a serverhttp.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 World\n');}).listen(1337, "127.0.0.1"); // listen on port 1337

// debug informationconsole.log('Server running at http://127.0.0.1:1337/');

https://github.com/sudar/jsfoo/blob/master/http-server.js

Node.JS – As a clientvar http = require('http'); // require the needed modules

// make the request objectvar request = http.request({ 'host': 'sudarmuthu.com', 'port': 80, 'path': '/', 'method': 'GET'});

// assign callbacksrequest.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

ProcessesFilesystemNetworkingUtilities

The entire list can be found at http://nodejs.org/docs/v0.4.12/api/

Core Modules - ProcessesNode allows you to analyze your

process and manage external process

Available Modules

processchild_process

Code samples: http://github.com/sudar/jsfoo/process.js

Core Modules - Filesystem

Low level API to manipulate files

Available Modules

fspath

Code Samples: http://github.com/sudar/jsfoo/filesystem.js

Core Modules - NetworkingAvailable Modules

netdgramhttptlshttpsdns

Code Samples: https://github.com/sudar/jsfoo/blob/master/dns.js

Core Modules - Utilities

Provides utility methods

Available Modules

consoleutil

Code Samples: https://github.com/sudar/jsfoo/blob/master/console.js

Node.JS is useful for..Writing highly concurrent server

applicationsSharing application logic between

server and clientPeer-to-peer web applications

using websockets

TerminologiesNPM – Package manager (like

apt-get)Modules – Plugins or add-ons for

Node.JSExpress – MVC framework (like

RoR)Jade – Template Engine (like

Smarty)Socket.IO – A websockets Library

Linkshttp://github.com/sudar/jsfoo (all

code samples used in this talk)http://nodejs.orghttp://npmjs.orghttp://expressjs.comhttp://socket.io

Questions

Thank you

Sudar Muthuhttp://sudarmuthu.comhttp://github.com/sudarhttp://twitter.com/sudarmuthu