1. APIs/Services for
Mobile Apps
(in Ruby)
Andrei Navarro

2. Background
● Web development for Startups
○ Web Products (w/ APIs)
● .NET, PHP, Ruby (Rails, Ramaze)
● Currently:
○ Tech Guy at Scrambled Eggs
○ Faculty at Ateneo de Manila
● PHRUG, Startup Weekend
● Geekcamp

3. History
● 80 - 90s: Computers for "Business" use
● 90s - Early 00s: "dotcom" era; ecommerce
○ Web TV
● Mid 00s: "Web 2.0"

4. History

5. Recent Years
● Late 00s - 10s: Mobile Era
○ Faster mobile internet speed
○ Easier access to devices
○ Exponential growth in users
○ "App" Era
● People becoming App developers instead of
going into Web

6. Mobile Apps need Web
● Web developers are still relevant
○ Need to provide data/interconnectedness to mobile
apps
○ Moving from Application layer to
Presentation/Session layer

7. Similarities with RIA
● Javascript/AJAX makes requests to your
backend -- which is connected to your
database

8. AJAX architecture

9. Quick Story (Amundsen vs Scott)
● The Antarctic Race
○ http://www.slideshare.net/apigee/amundsens-dogs-
information-halos-and-apis
● Apps are the "South Pole"
● Native Wisdom: Your APIs support and
strengthen your mobile apps (whether built
by yourself or by a developer community)

10. Mobile App Data Architecture

11. Building APIs
● Just like any other web app
○ no view layer (HTML/CSS/JS)
○ apps "view" your API
● Transfer is via HTTP/HTTPS
● Plan your format
○ JSON, XML, SOAP etc.
○ REST/RPC?
○ Parsing capability on client end
● Scalability
● Sessions and Authentication
○ token-based
○ header-based
○ devise

12. Design-by-Contract
● Define your "interface" that will supply the
mobile app with JSON/XML data
○ use mocks!
● When building your API, conform to that
interface
● Allows parallelization of development

13. Testing
● Web apps are tested on a browser
● APIs ultimate test is on the target clients
● Development usually happens in parallel --
and you need to validate your API works
before app is completed
○ rest-client gem
○ rest-client chrome/firefox extensions

14. Building it with Rails
● Rails already supports RESTful architecture
● Rails already supports multiple formats
● Can use RSpec/Test::Unit to validate API
requests
● Variety of existing gems already tested and
well integrated with Rails

15. Issues with Rails
● Issues for APIs (not in general)
● Adds a lot of dependencies that aren't
needed for your purpose
○ Wasted memory
● Cherry pick middleware and modules from
the stack
○ hassle.
● Others
○ http://engineering.gomiso.com/2011/05/16/if-youre-
using-to_json-youre-doing-it-wrong/

16. Some solutions
● RABL (Ruby API builder language)
○ https://github.com/nesquena/rabl
● Rails-API
○ https://github.com/rails-api/rails-api
○ a subset of rails specifically for building APIs

17. Microframeworks
● Much lighter than Rails
○ Sinatra/Padrino
○ Ramaze
○ Merb
○ Camping
● Build only what you need
○ smaller footprint
● You'll need to know Ruby well
○ that's actually a good thing

18. Grape Framework
● https://github.com/intridea/grape
● From Intridea, creators of OmniAuth
● "An opinionated microframework for creating
REST-like APIs in Ruby"
Generalized
Rapid
API
Erector

19. Grape Framework

20. Grape Framework
● Rack-based
○ easy deployment over passenger
○ run via config.ru
○ can sit alongside your Rails app
■ mount My::API in config/routes.rb
● Different content-types supported
● Fun HTTP stuff (headers, verbs, status
codes etc)
● Entities: grouping/presenting your data into
"Models"
● Killer feature: API versioning

21. API Versioning
Traditional Web Development

22. API Versioning
● Support several versions of Mobile apps
○ up to client/user to update
● App store problem
○ Dev
○ Staging
■ App store staging
○ Production
■ App store production

23. API Versioning

24. Recommendations
● MVC-ize your application
○ It's just good design.
● Use Devise/Omniauth for authentication
○ token-based authentication
● Use oj gem for JSON
○ https://github.com/ohler55/oj
○ faster Json parser/encoder compared to native ruby
JSON parsing
● Use ox gem for XML

25. Questions?
@dreinavarro