Introduction to Node.js

How does it work? What makes it different? When would

you use it? And most importantly, why does it matter?

Girish Gangadharan @appoosa

What is Node.js?

Development

platform

“Node.js is lightweight and efficient which makes it perfect for building fast, scalable network

applications that run across distributed devices.”

Built on Chrome's JavaScript

engine

Event-

driven

Non-blocking I/O

model

Wait a minute….

Umm…not really.

JavaScript on the server

JavaScript was supposed to be a server-side language as well.

Netscape Enterprise Server

Source: http://www.thefreelibrary.com/NETSCAPE+INTRODUCES+NETSCAPE+ENTERPRISE+SERVER(TM)+2.0-a018056425

“ Netscape Enterprise Server 2.0 is the first web server to support the Java(TM) and JavaScript(TM) programming languages, enabling the creation, delivery and

management of live online applications. ”(March 1996)

Traditional web servers

Anyway, let’s see how web servers work currently…

Current setup

Each request to a traditional web server gets handed over to a thread (picked from a limited thread pool) for processing.

Typically….

Request 1 Request 2 Request n …

Thread 2 …

(m < n)(for a busy site, m could be a fraction of n)

Thread 1

Thread m

How does it scale?

So if there are 10,000 requests coming in at the same time, and each requires executing a long-running task (DB transactions, network I/O, etc.) ….

How does node.js address it?

So what does node.js bring to the table?

Single thread processing.

And how does it work?

behind the scenes

Source: http://www.aaronstannard.com/post/2011/12/14/Intro-to-NodeJS-for-NET-Developers.aspx

Simple “hello world” app

hello-world app in node.js

// Load the http module to create an http server.var http = require('http'); // Configure the HTTP server.var server = http.createServer(function (request, response) {  response.writeHead(200, {"Content-Type": "text/plain"});  response.end("Hello, world");}); // Listen on port 8000, IP defaults to 127.0.0.1server.listen(3000); // Log message to the terminalconsole.log("Server running at http://127.0.0.1:3000/");

Demo

Let’s write some code.

What makes it different?

It’s JavaScript! (everybody know JavaScript, right?)Single threaded (avoid concurrency issues) (single threaded out of the box, but still supports multi-threading)

Super efficient (can handle 100s of 1000s of connections/minute)Great for real-time applications (because of low latency)

And….it’s FREE! (no licensing costs, no expensive dev tools)

Vibrant community (15,000+ packages)

Why does it matter?

It matters because just like with any other technology, Node.js is not perfect.

Don’t start using it because it’s new and shiny.

for example, it’s not the best solution for CPU intensive requests processing

We don’t need another bubble.

When should you use it?

Multi user, real time apps - mobile games, collaboration tools, chat rooms, etc.

APIs exposing JSON based DBs- no need to do any JSON conversion (since it’s

JavaScript)Data Streaming

- Can process files as they’re still being uploaded (using Streams)Single page apps

- AJAX heavy apps can benefit from node’s low response times

We’re done

Questions?

Girish Gangadharan @appoosa