Intro to Node.JS

By Aaron StannardStartup Developer Evangelist, Microsoft Corporation

Examples from Today’s Talk

https://github.com/Aaronontheweb/introtonode

Meet Node

var http = require('http');

//Node function called each time a new HTTP request arrivesfunction onRequest(req, res){ res.writeHead(200, {'Content-Type':'text/plain'}); res.end('Hello ' + req.connection.remoteAddress + '!'); /* Write the IP addresses of our connecting client to console */ console.log('Incoming connection from ' + req.connection.remoteAddress);}

//Listen for connections on the port provided by the host processvar server = http.createServer(onRequest).listen(process.env.PORT);

What Is Node?

• Server Side JavaScript• Asynchronous Web Framework• Evented I/O Model

What Is Node?

Network I/O Libraries

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What Makes Node Special?

• Uses the familiar JavaScript programming model to enable server-side development

• Buries the pain of working with async / parallel programming

• No Blocking I/O• Can handle large concurrent loads more easily

than other technologies• Not a silver bullet

Why Node

JavaScript is ubiquitous

Why Node

Traditional Platforms• Things you need for

concurrent web programming:– Locks– Threads / Thread Pools– Thread Management– Inter-Thread Communication– Callbacks + Enclosures + Sync

to Blocking Calls

Node• Things you need for

concurrent web programming:– Callbacks + Enclosures

Which looks simpler?

Good Node Scenarios

Behavior• High request volume, low

response-sizes• Pub / Sub

• Real-time applications

Application• Online games, message

passing services• Social networks, content-

syndication services• Chat, real-time games

Bad Node Scenarios

Behavior• Large HTTP response sizes

• CRUD• Transaction-heavy systems

Application• Static file servers, reporting

tools• Blogs, CMS• E-Commerce

Node Concepts

• What Do Node Projects Look Like?• Event Loop & Workers• HTTP as a First Class Citizen• Callbacks and Functions as Objects• Modules & Packages

Structure of a Node Project/projectroot/

package.jsonreadme.txtweb/server.jsviews/index.htmlmodels/post.jshelpers/timestamp.jstest/route-test.jspost-test.jsnode_modules/

C:\[projectroot]> node web/server.jsNode server listenening on port 3000 in development mode

Tells Node and NPM what packages are required

The main entry point for your application

User-defined module for handling persistence

User-defined module for other stuff

Root of your actual application

Directory for unit tests

Output directory for all NPM installations

Event Loop + Workers

Client

Clients send HTTP requeststo Node.JS server...

EventLoop

(single thread)

Event loop is woken up by OS.Passes request + responseobjects to worker functionswith callbacks.

Long-running jobsrun on worker threads..

Non-blockingWorker

(internal C++ threadpool)

Responses are sentto main thread viacallback

Event loop returnsresult to client

HTTP

• HTTP is a first class citizen• Request Object– Holds properties about the client– Holds session state– Passes client-data to request handlers

• Response Object– Holds the HTTP response stream– Can be written in chunks

Callbacks and Functions as Objects

// HTTP GET /app/listexports.listapps = function(req, res){

var pageTitle = req.session.userName + "'s Apps";

appProvider.getAppsForUser(req.session.userName, function(error, userApps){

if(error){console.log(error.message);return res.redirect('/');

}

res.render('list_apps', {locals:{title: pageTitle, apps:userApps}})

});}

Modules & Packages

• Including a built-in modulevar http = require('http');

• Including your own module[timestamp.js] exports.currentTime = function(){…}

[server.js] var timestamp = require(‘./helpers/timestamp');[server.js] console.log(timestamp.currentTime());

• Node Package Manager (NPM)[Commandline] C:\> npm install express[server.js] var express = require(‘express’);

Microsoft & Node

Microsoft wants Windows Azure to be an option for developers regardless of stack

=>

Node on Windows Azure

• IISNode• Windows Azure Node PowerShell Cmdlets• Windows Azure Node SDK• Cloud9 IDE

IISNode

• Hosts Node applications in IIS as native modules

• Automatically manages life-cycle of node.exe• Can load-balance multiple node.exe processes

Azure / Node Powershell Cmdlets

• Create new Azure Services• Add Node Web and Worker Roles• Deploy to Azure Emulator• Import Publish Settings• Deploy to Azure (Production / Staging)• Source @ Github

Windows Azure SDK

• Loads Storage Settings from Web.config• Azure Tables• Azure Blobs• Azure Queues

[console] C:\> npm install azure

Source @ Github

Cloud9 IDE

• Browser-based IDE• Deploys to Windows Azure• Only way to deploy without Windows Vista / 7

Popular Node Frameworks and Tools

• Express (MVC)• Connect• Socket.IO• Unit Testing:– Assert (built-in)– Nodeunit

Further Reference

• NodeBeginner.org - Used this to teach myself Node when I was first getting started.

• NodeJS.org - Official Node Homepage• Github.com/WindowsAzure – Azure bits

About Me

• Aaron Stannard– Twitter: @Aaronontheweb– Github: @Aaronontheweb– Blog: http://www.aaronstannard.com/