Post on 12-May-2015
Buildingbusinesspost.ie
Richard Rodger@rjrodger
Friday 9 November 2012
businesspost.ie
Friday 9 November 2012
Everything JavaScript.
Friday 9 November 2012
So, how do you build it?‣have a common code-base,‣be service-oriented,‣use small, independent pieces.
Friday 9 November 2012
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
Friday 9 November 2012
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
Friday 9 November 2012
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
Friday 9 November 2012
Native AppsSame code as mobile web versions, ...
... wrapped using PhoneGap to run natively
... plus some native plugins
Friday 9 November 2012
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 ) { ... }
Friday 9 November 2012
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
Friday 9 November 2012
this is the common language of Node.js - always use it!
Callback Style
doSomething( input, function( error, output ) { ...})
Friday 9 November 2012
function wraperror( success ) { return function( err, result ) { if( err ) return handleError( err ); else return success( result ); }}
database.doQuery( wraperror( function( result ) { doRealWork( result );}))
use functional style avoidif statements everywhere
Error Pattern
Friday 9 November 2012
Database Hosting Monitors
MongoDB
Redis
memcached
Amazon
Load Balancer
Instance Scaling
Amazon
cloudkick
Continuous
Cloud Services
Friday 9 November 2012
Analytics
Logging
Integrations...
E-Commerce
In-App Purchasing
Stock Feed
JSON, XML, simple form data, text files, ... ... all easy using JavaScript and Node.js Modules
Friday 9 November 2012
Lots of Little Processes‣Web API‣RSS reader‣Image resizer
‣Admin site‣Search index‣Sitemap
Friday 9 November 2012
Use queues!This is how processes talk.
Friday 9 November 2012
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...
Friday 9 November 2012
Node.js modules.
Friday 9 November 2012
Write small modules, not big apps!
Friday 9 November 2012
businesspost.ie modules‣underscore,‣connect,‣express,‣appgen,‣seneca
Friday 9 November 2012
‣npm install underscore‣underscorejs.org‣do functional programming‣provides "missing" JS features‣useful for handling arrays, objects
underscoremodule
Friday 9 November 2012
‣npm install connect‣senchalabs.org/connect‣build web services‣provides "middleware" pattern‣useful for HTTP request handling
connectmodule
Friday 9 November 2012
‣npm install express‣expressjs.com‣build websites‣provides HTML page handling‣useful for building dynamic sites
expressmodule
Friday 9 November 2012
‣npm install appgen‣appgenjs.org‣build multi-platform web apps‣generates multiple code versions‣useful for organizing platform code
appgenmodule
Friday 9 November 2012
‣npm install seneca‣senecajs.org‣build business logic‣provides "command" pattern‣useful for organizing features
senecamodule
Friday 9 November 2012
businesspost.ie lessons.
Friday 9 November 2012
Lesson:
Friday 9 November 2012
Lesson:
0
1
2
3
4
Client JavaScript Server JavaScript
code volume
Friday 9 November 2012
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!
Friday 9 November 2012
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!
Friday 9 November 2012
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
Friday 9 November 2012
Thank You!
Richard Rodger@rjrodger
Friday 9 November 2012