API-based client/server applications with TDD and ActiveResource github: http://github.com/wolframarnold/tdd_with_activeresource

1. API-based client/serverAPI-based client/server
applications with TDD andapplications with TDD and
ActiveResourceActiveResource
Wolfram ArnoldWolfram Arnold
www.rubyfocus.bizwww.rubyfocus.biz
In collaboration with:In collaboration with:
Kurt SnyderKurt Snyder
papercheck.compapercheck.com
marakana.commarakana.com

2. Database-backedDatabase-backed
DB
Application
ActiveRecord
SQL

3. API-backedAPI-backed
Client
Application
ActiveResource
Server
Application
API
JSON
DB
SQL

4. Tradeoffs?Tradeoffs?
DB-backed
Fast
ActiveRecord well developed
Complex relationships possible
Limited scalability—tight coupling
API-backed
Extra network & server latency
Complex relationships more difficult
Scales well to different front-ends—loose coupling

5. Client
Application
(Flash or JS)
Frontend ScalabilityFrontend Scalability
Client
Application
ActiveResource
Server
Application
API
JSON
DB
SQL
Client
Application
(Mobile)

6. Rails ActiveResourceRails ActiveResource
Model objects that behaves ActiveRecord objects
Maps CRUD operations to RESTful API
No Associations
No Validations (added in Rails 3)
Rougher around the edges than ActiveRecord

7. From CRUD to RESTFrom CRUD to REST
class Person < ActiveResource::Base
site “http://server.example.com/people”
format :json
end
Person.create(:name => “Joe”)
→ POST /people, {'name':'Joe'}
Person.find(4)
→ GET /people/4

8. Resourceful RoutesResourceful Routes
map.resources :people (in config/routes.rb)
people_path, people_url “named route methods”
GET /people → “index” action
POST /people → “create” action
new_person_path, new_person_url
GET /people/new → “new” action
edit_person_path, edit_person_url
GET /people/:id/edit → “edit” action with ID
person_path, person_url
GET /people/:id → “show” action with ID
PUT /people/:id → “update” action with ID
DELETE /people/:id → “destroy” action with ID

9. Hyperactive ResourceHyperactive Resource
http://github.com/taryneast/hyperactiveresource
Adds Associations
Supports nested routes
/people/5/addresses/3
But: Cannot mix nested and non-nested routes for the
same resource
Adds Validations

10. Let's do some codingLet's do some coding
Demo
RESTful Person Server API with JSON
HyperactiveResource-based client

11. TDD anyone?TDD anyone?
DB
Application
ActiveRecord
SQL
RSpec model tests
with fixtures, factories
Test Database
with transaction support

12. TDD ActiveRecord StyleTDD ActiveRecord Style
it “should create the object” do
lambda {
Person.create(:first_name => “Joe”)
}.should change(Person, :count).by(1)
end
it “should destroy the object” do
p = Factory.create(:person)
lambda {
p.destroy
}.should change(Person, :count).by(-1)
end

13. API-backedAPI-backed
Client
Application
ActiveResource
Server
Application
API
JSON
DB
SQL
RSpec model test
Test Database
on
Test Server
instance!

14. Mocks anyone?Mocks anyone?
FakeWeb gem: http://github.com/chrisk/fakeweb
FakeWeb.register_uri(:get,
"http://server.example.com/people",
:body => "Hello World!")
Body is the mock object.
It should simulate the server response.
Great solution if it's a 3rd
party server.

15. Problems with Mocks?Problems with Mocks?
If the server code is under our control...
What happens if the server API changes but the
mock doesn't?
What process keeps the simulated server
responses and the actual API in sync?
Better ideas?

16. Beyond MocksBeyond Mocks
Remote Specs
Rely on remote server running (in test environment)
Mechanism to set up data
Mechanism to inspect data
Mechanism to clean up data

17. Distributed Ruby “DRb”Distributed Ruby “DRb”
Client
Application
DRb Client
Server
Application
DRb Server
DRb
Remote
Method
Invocation
foo(args)
foo(args)

18. Demo DRb

19. Gotcha'sGotcha's
ActiveResource::Base.include_root_in_json
after_initialize hook for starting DRb server
:id problem for Objects, via DRb
Need to run server in test mode
Ideas/Questions:
Front Object in DRb?
rake task to start/stop server—reliably find process?
DRb port inflation—better way?

20. SummarySummary
Server application with REST controller
Client application with ActiveResource
Use DRb to:
test objects
inquire “actual” data
TDD with ActiveResource

21. BizConfBizConf
Aug 4-6, 2010
Amelia Island, FL
Discount code: WOLF
for 43% off
http://bizconf.org?
coupon=WOLF
Rails & Web App
Professionals, Entrepreneurs,
Consultants
Small group
Network with Who's Who
Organized by Obie
Fernandez of Hashrocket
Highlight: David Allen