building businesspost.ie using node.js

Buildingbusinesspost.ie

Richard Rodger@rjrodger

Friday 9 November 2012

businesspost.ie


Everything JavaScript.


So, how do you build it?‣have a common code-base,‣be service-oriented,‣use small, independent pieces.


Mobile Web Apps

Web Services

API

Cloud Services

Mobile & Tablet Web

Mobile & Tablet Apps

Desktop Web

REST & JSON

Horizontal Scale

Cloud Hosted

Database

Third Party Services

Monitoring


Client-side•Common code-base

• even for hybrid apps!

•backbone.js

• shims for weak browsers

•browser-targeting: user-agent & capabilities

• responsive layout (mostly)

Models

Views

Router

Helpers

#! URLs

Data, biz logic

DOM Layout

Shared code


Running...1. Load static index.html and assets

2. Init shared code, then targeted code

3. Init router, and display as per #! URL

4. Wait for events


Native AppsSame code as mobile web versions, ...

... wrapped using PhoneGap to run natively

... plus some native plugins


Server-side• nginx & Node.js

• Small code volume

• Third party modules:

• connect

• express

• seneca

• Deploy with:

• sudo killall node

API functions

Helpers

Router

Modules

map /api/ URLs

to functions

Shared code

(some with client)

Open source

heavy-lifting

function( req, res ) { ... }


Running...1. Connect to databases and listen for HTTP

2. Route HTTP requests to API functions

3. Talk to database, wait for callback

4. Send JSON back to client


this is the common language of Node.js - always use it!

Callback Style

doSomething( input, function( error, output ) { ...})


Database Hosting Monitors

MongoDB

Redis

memcached

Amazon

Load Balancer

Instance Scaling

Amazon

cloudkick

Continuous

Cloud Services


Analytics

Logging

Email

Integrations...

Twitter

Facebook

LinkedIn

E-Commerce

In-App Purchasing

Stock Feed

JSON, XML, simple form data, text files, ... ... all easy using JavaScript and Node.js Modules


Lots of Little Processes‣Web API‣RSS reader‣Image resizer

‣Admin site‣Search index‣Sitemap


Use queues!This is how processes talk.


redis.publish("images", "/storage/img1234.jpg");

news reader finds an image...... and pushes it onto queue

Example!

redis.subscribe("images");redis.on("message", function(channel, message) { resizeImage( message ) // message == "/storage/img1234.jpg"});

then image processor resizes...


Node.js modules.


Write small modules, not big apps!


businesspost.ie modules‣underscore,‣connect,‣express,‣appgen,‣seneca


‣npm install underscore‣underscorejs.org‣do functional programming‣provides "missing" JS features‣useful for handling arrays, objects

underscoremodule


‣npm install connect‣senchalabs.org/connect‣build web services‣provides "middleware" pattern‣useful for HTTP request handling

connectmodule


‣npm install express‣expressjs.com‣build websites‣provides HTML page handling‣useful for building dynamic sites

expressmodule


‣npm install appgen‣appgenjs.org‣build multi-platform web apps‣generates multiple code versions‣useful for organizing platform code

appgenmodule


‣npm install seneca‣senecajs.org‣build business logic‣provides "command" pattern‣useful for organizing features

senecamodule


businesspost.ie lessons.


Lesson:


Lesson:

0

1

2

3

4

Client JavaScript Server JavaScript

code volume


Lesson:multi-platform client-side JavaScript is really hard

• a framework is a must

• backbone.js

• business logic must be in common code

• browser-specific code

• virtual .js files

• use jshint to keep IE happy

• code against ECMA, use shims to support older browsers

• Code/Test/Debug inside Safari

• phonegap.github.com/weinre for hard to reach places

• use error capture in production

• Finally, use a simple static site as a fallback (also for Googlebot)

• appgen module helps!


http://phonegap.github.com/weinre

http://phonegap.github.com/weinre

Lesson:multi-platform HTML/CSS is really hard

• "structured" CSS is a must

• sass or less

• Be happy with

•media queries

•CSS3 transforms

• browser-specific code

• virtual .css files

• Clean, semantic HTML is not optional

• graceful degradation may require radically different CSS

• 100% "Responsive" design is tough

• Responsive within browser subsets has higher reward/effort

•appgen module helps!


Lesson:the app stores are not web sites

• that bug in version one...

•will take two weeks to fix via an update

• some users will never update

• appears after an OS update

• you can't deploy hot fixes

•make everything configurable!

•All prices, text, host names, urls, ...

•On launch, app "checks-in" for new configuration

• this will save your lifeFriday 9 November 2012

Lesson:Node.js is awesome!

• High performance

• High throughput

• Low CPU usage

• Constant memory usage

• leaks will kill, but then

• < 100ms startup time

• means you may not notice!

• callback spaghetti is not a problem in practice

•use functional style

• client-side code is far more difficult

•Don't do CPU intensive stuff

•Node.js is not for thatFriday 9 November 2012

Lesson:Small processes can save your life

• Prevents total failure even if other systems fail

• Easy to scale - just move to new machines

• Easy to code - you get small, single purpose code bases

• Easy to manage - even traditional process management will get you a long way

•Memory leaks are not a disaster - just restart!

•Use queues in preference to direct communication

•Easy to divide up work between developers


Thank You!

Richard Rodger@rjrodger


building businesspost.ie using node.js

Technology

urls common codebase

native appssame code

function error

multiplatform client

return function

googlebot use jshint

mobile web versions

web sites