Slide from my talk at Shanghai on Rails on Saturday 21st, May 2011.

1. Rails as iOS Application Backend
Shanghai On Rails – Saturday 21st, 2011

2. iOS Applications
• Which website doesn’t have an iPhone application ?
• iPhone application add a mobility aspect to your web
application - GPS, on-the-go, etc.
• Push notifications brings retention

3. As a Rails Developer,
why do I care about mobile?

4. Mobile websites

5. Mobile websites

6. Mobile websites

7. You will probably have to make
an API for the iPhone / iPad or

8. Architecture

9. Architecture

10. Architecture

11. Architecture
Rails
application

12. Architecture
Database
Rails
application
3rd party
APIs

13. Architecture
Database
Rails
application
3rd party
APIs JSON

14. Architecture
Database
Rails
application
3rd party
APIs JSON
REST

15. Architecture
Database
Rails
application
3rd party
APIs JSON
REST
over HTTP(s)

16. Architecture
Database
Rails
application
3rd party
APIs
Apple Push
Notification
Services

17. Challenges
• Authentication and Persistence
• Data format and optimization
• Push notifications scheduling

18. Authentication
• Havethe iPhone behaves
as a web browser.
• Sending cookies with
every request
• Persisting cookies on the
iPhone
• Good news for your Railer:
nothing new!

19. Authentication
• Havethe iPhone behaves
as a web browser.
• Sending cookies with authlogic
every request devise
....
• Persisting cookies on the
iPhone
• Good news for your Railer:
nothing new!

20. Authentication
• Havethe iPhone behaves
as a web browser.
• Sending cookies with authlogic
every request devise
....
• Persisting cookies on the Cookies!
iPhone
• Good news for your Railer:
nothing new!

21. Authentication
• Havethe iPhone behaves
as a web browser.
• Sending cookies with authlogic
every request devise
....
• Persisting cookies on the Cookies!
iPhone
• Good news for your Railer:
nothing new!

22. Authentication
Example using inherit_resources and authlogic

23. iOS side
Application code
• Not as easy.
• NSURLConnection is JSONRequest
low level
NSURLConnection
• JSONRequest provides
you a higher level iOS Network Socket
interface

24. JSONRequest
➊ Initiate HTTP request to /inventory
➋ Handle networking, cookies, redirections and errors
➌ Parse HTTP Response as JSON

25. JSONRequest
Your delegate receives one of those two calls

26. JSONRequest
• Youget a NSDictionary object easy to manipulate, you
can view it has a the equivalent of a Ruby hash
{status: “ok”}

27. What about models?

28. We created a lightweight
ORM for the iOS platform

29. Models - Rails

30. Models - iOS

31. Models - iOS

32. Models - How to use it

33. Models - How to use it
/counters.json

34. Models - How to use it
/counters.json

35. Models - How to use it
/counters.json
/counters.json?name=shield

36. Models - How to use it
You directly manipulate objects, not JSON objects

37. Back to Rails

38. https://github.com/maxime/iorm
Application code
JSONRequest
NSURLConnection
iOS Network Socket

39. https://github.com/maxime/iorm
Application code
ORM
JSONRequest
NSURLConnection
iOS Network Socket

40. Tips
• Why not using the built-in .to_json ?

41. Built-in to_json
2k bytes
> puts Counter.all.to_json
[{"counter":{"level_id":2,"name":"Mend","created_at":"2011-01-11T10:56:02Z","strength":11,"cost":
2,"updated_at":"2011-04-28T18:10:28Z","id":12,"initial_stock":25,"inventory_icon_id":21}},{"counter":{"level_id":
2,"name":"Radiate","created_at":"2011-01-11T10:57:19Z","strength":11,"cost":2,"updated_at":"2011-04-28T18:10:30Z","id":
13,"initial_stock":25,"inventory_icon_id":10}},{"counter":{"level_id":
4,"name":"Float","created_at":"2011-01-11T10:50:37Z","strength":31,"cost":4,"updated_at":"2011-04-28T18:10:33Z","id":
10,"initial_stock":15,"inventory_icon_id":31}},{"counter":{"level_id":
2,"name":"Shine","created_at":"2011-01-11T10:52:47Z","strength":31,"cost":4,"updated_at":"2011-04-28T18:10:35Z","id":
11,"initial_stock":25,"inventory_icon_id":12}},{"counter":{"level_id":
6,"name":"Pure","created_at":"2011-01-11T10:50:18Z","strength":51,"cost":6,"updated_at":"2011-04-28T18:10:38Z","id":
9,"initial_stock":10,"inventory_icon_id":30}},{"counter":{"level_id":
8,"name":"Bounce","created_at":"2010-12-20T19:39:05Z","strength":51,"cost":6,"updated_at":"2011-04-28T18:10:41Z","id":
1,"initial_stock":5,"inventory_icon_id":8}},{"counter":{"level_id":
9,"name":"Reflect","created_at":"2011-01-11T08:56:10Z","strength":71,"cost":8,"updated_at":"2011-04-28T18:10:44Z","id":
6,"initial_stock":10,"inventory_icon_id":9}},{"counter":{"level_id":
11,"name":"Detect","created_at":"2011-01-11T08:57:06Z","strength":81,"cost":10,"updated_at":"2011-04-28T18:10:48Z","id":
7,"initial_stock":10,"inventory_icon_id":26}},{"counter":{"level_id":
10,"name":"Healer","created_at":"2011-01-11T10:49:49Z","strength":81,"cost":10,"updated_at":"2011-04-28T18:10:52Z","id":
8,"initial_stock":5,"inventory_icon_id":34}},{"counter":{"level_id":
11,"name":"Counter","created_at":"2011-01-11T10:58:24Z","strength":101,"cost":25,"updated_at":"2011-04-28T18:10:55Z","id":
14,"initial_stock":10,"inventory_icon_id":28}},{"counter":{"level_id":
11,"name":"Return","created_at":"2011-01-11T08:54:57Z","strength":151,"cost":50,"updated_at":"2011-04-28T18:10:57Z","id":
5,"initial_stock":5,"inventory_icon_id":20}}]

42. Write your own .to_json
1k byte
> puts Counter.all.map(&:to_json).to_json
[{"name":"Mend","strength":11,"id":12,"icon":"/system/pictures/21/large/Glass-2.png?1299820062"},{"name":"Radiate","strength":
11,"id":13,"icon":"/system/pictures/10/large/potion-1.png?1299786958"},{"name":"Float","strength":31,"id":10,"icon":"/system/
pictures/31/large/Untitled-1.png?1299820281"},{"name":"Shine","strength":31,"id":11,"icon":"/system/pictures/12/large/
point-3.png?1299787038"},{"name":"Pure","strength":51,"id":9,"icon":"/system/pictures/30/large/Umbrella-3.png?1299820262"},
{"name":"Bounce","strength":51,"id":1,"icon":"/system/pictures/8/large/shield-2.png?1299786772"},{"name":"Reflect","strength":
71,"id":6,"icon":"/system/pictures/9/large/shield-3.png?1299786787"},{"name":"Detect","strength":81,"id":7,"icon":"/system/
pictures/26/large/Shield-1.png?1299820172"},{"name":"Healer","strength":81,"id":8,"icon":"/system/pictures/34/large/Vest-3.png?
1299820340"},{"name":"Counter","strength":101,"id":14,"icon":"/system/pictures/28/large/Shield-3.png?1299820222"},
{"name":"Return","strength":151,"id":5,"icon":"/system/pictures/20/large/Glass-1.png?1299820042"}]
By writing your own to_json method, you not only
optimize the size of the body but also you can be
much more specific and prepare your own data

43. Push Notification

44. Push Notification
Apple Push
Rails
Notification
application
Services

45. Push Notification

46. Push Notification

47. Push Notification

48. Push Notification
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1b19102c 0e652002 6ca9a785

49. Push Notification
• Push Notification Token identifies one device, not one
user
• Send it to your Rails backend and save it to your data
storage

50. Push Notification
• Rails plugin: apn_on_rails
• http://www.github.com/PRX/apn_on_rails
• Rails3 branch

51. Push Notification
This saves the message to your database

52. Push Notification
Every ten minutes.. or every minute..

53. Push Notification
• Rake task triggered by crontab
• Resque scheduler
• Ifyou want to schedule a Rake task every minute or even
every 5 minutes, you will consume a lot of resources on
your server to boot up the Rails environment.
• Be careful about 256 bytes size limit!

54. Resque Scheduler

55. Thank you
• maxime@ekohe.com
• Thanksto maverick@ekohe.com for his contribution on
the JSONRequest / Model ORM
• Thanks
to jimmy@ekohe.com for writing an awesome
backend for Breeze Living