my presentation at houston.rb on Grape, the API builder for rack based systems using a friendly ruby/sinatra like interface. It makes separating out your API from you web app logic really easy.

1. 2011:A Grape Odyssey
(easy api’s using Grape)

2. Introduction
Mike Hagedorn
@mwhagedorn

3. In the beginning

4. In the beginning

5. In the end..
Ends up a mess...
So how do people deal
with this? lead into next

6. In the end..
Ends up a mess...
So how do people deal
with this? lead into next

7. In the end..
Ends up a mess...
So how do people deal
with this? lead into next

8. Rails?

9. Rails?
• Too Much

10. Rails?
• Too Much
• Overlapping WebUI and “data”
responsibilities

11. Sinatra?
• Too manual

12. Rack App?
• Even MORE manual

13. “Lagom”

14. “Lagom”
• Swedish for “just the right amount”

15. “Lagom”
• Swedish for “just the right amount”
• “Small things, loosely joined, written fast”
- Justin Gehtland

16. “Lagom”
• Swedish for “just the right amount”
• “Small things, loosely joined, written fast”
- Justin Gehtland
• Separation of concerns

17. “Lagom”
• Swedish for “just the right amount”
• “Small things, loosely joined, written fast”
- Justin Gehtland
• Separation of concerns
• Testability, Scalability

18. Grape

19. Grape
• Generalized Rapid API Erector

20. Grape
• Generalized Rapid API Erector
• Grape is a REST-like API micro framework

21. Grape
• Generalized Rapid API Erector
• Grape is a REST-like API micro framework
• Heavily influenced by Sinatra

22. Grape
• Generalized Rapid API Erector
• Grape is a REST-like API micro framework
• Heavily influenced by Sinatra
• Ruby based

23. Hello World

24. Hello World
require 'grape'
class Bar < Grape::API
get 'hello' do
{:hello =>'world'}
end
end

25. Hello World
require 'grape'
class Bar < Grape::API
get 'hello' do
{:hello =>'world'}
end
end
>GET /hello
{“hello”:”world”}

26. JSON Serialization

27. JSON Serialization
• Automatically invokes #to_json on returns

28. JSON Serialization
• Automatically invokes #to_json on returns
• Other formats soon

29. Prefixing

30. Prefixing
require 'grape'
module TestApp
class Bar < Grape::API
prefix "api"
resource "widgets" do
get do
Widget.all
end
get ":id" do
Widget.find(params[:id])
end
end
end
end

31. Prefixing
require 'grape'
module TestApp
class Bar < Grape::API
prefix "api"
resource "widgets" do
get do
Widget.all
end
get ":id" do
Widget.find(params[:id])
end
end
end
end
>GET /api/widgets/1

32. Prefixing
require 'grape'
module TestApp
class Bar < Grape::API
prefix "api"
resource "widgets" do
get do
Widget.all
end
get ":id" do
Widget.find(params[:id])
end
end
end
end
>GET /api/widgets/1
{“name”:”widget1”}

33. Prefixing
require 'grape'
module TestApp
class Bar < Grape::API
prefix "api"
resource "widgets" do
get do
Widget.all
end
get ":id" do
Widget.find(params[:id])
end
end
end
end
>GET /api/widgets >GET /api/widgets/1
{“name”:”widget1”}

34. Prefixing
require 'grape'
module TestApp
class Bar < Grape::API
prefix "api"
resource "widgets" do
get do
Widget.all
end
get ":id" do
Widget.find(params[:id])
end
end
end
end
>GET /api/widgets >GET /api/widgets/1
[{“name”:”widget1”}] {“name”:”widget1”}

35. Versioning
require 'grape'
module TestApp
class Bar < Grape::API
resource, namespace,
prefix “api” group all synonyms here
version "v2"
resource "widgets" do
get do
Widget.all
end
get ":id" do
Widget.find(params[:id])
end
end
end

36. Versioning
require 'grape'
module TestApp
class Bar < Grape::API
resource, namespace,
prefix “api” group all synonyms here
version "v2"
resource "widgets" do
get do
Widget.all
end
get ":id" do
Widget.find(params[:id])
end
end
end
>GET /api/v2/widgets

37. Versioning
require 'grape'
module TestApp
class Bar < Grape::API
resource, namespace,
prefix “api” group all synonyms here
version "v2"
resource "widgets" do
get do
Widget.all
end
get ":id" do
Widget.find(params[:id])
end
end
end
>GET /api/v2/widgets
[{“name”:”widget1”}]

38. Basic Authentication
require 'grape'
module TestApp
class Bar < Grape::API
prefix “api”
version "v2"
resource "widgets" do
get do
Widget.all
end
end
namespace :admin do
http_basic do |u,p|
u == 'admin' && p == YOURPASSWORD
end
namespace 'metrics' do get do
{:clicks => Click.count} end
end
end
end
end
OAuth soon...

39. Basic Authentication
require 'grape'
module TestApp
class Bar < Grape::API
prefix “api”
version "v2"
resource "widgets" do
get do
Widget.all
end
end
namespace :admin do
http_basic do |u,p|
u == 'admin' && p == YOURPASSWORD
end
namespace 'metrics' do get do
{:clicks => Click.count} end
end
end
end
end
OAuth soon...
admin:<password>

40. Basic Authentication
require 'grape'
module TestApp
class Bar < Grape::API
prefix “api”
version "v2"
resource "widgets" do
get do
Widget.all
end
end
namespace :admin do
http_basic do |u,p|
u == 'admin' && p == YOURPASSWORD
end
namespace 'metrics' do get do
{:clicks => Click.count} end
end
end
end
end
OAuth soon...
admin:<password>
>GET /api/v2/admin

41. Basic Authentication
require 'grape'
module TestApp
class Bar < Grape::API
prefix “api”
version "v2"
resource "widgets" do
get do
Widget.all
end
end
namespace :admin do
http_basic do |u,p|
u == 'admin' && p == YOURPASSWORD
end
namespace 'metrics' do get do
{:clicks => Click.count} end
end
end
end
end
OAuth soon...
admin:<password>
>GET /api/v2/admin
{“clicks”:1234}

42. Basic Authentication
require 'grape'
module TestApp
class Bar < Grape::API
prefix “api”
version "v2"
resource "widgets" do
get do
Widget.all
end
end
namespace :admin do
http_basic do |u,p|
u == 'admin' && p == YOURPASSWORD
end
namespace 'metrics' do get do
{:clicks => Click.count} end
end
end
end
end
OAuth soon...
admin:<password>
>GET /api/v2/admin
>GET /api/v2/admin
{“clicks”:1234}

43. Basic Authentication
require 'grape'
module TestApp
class Bar < Grape::API
prefix “api”
version "v2"
resource "widgets" do
get do
Widget.all
end
end
namespace :admin do
http_basic do |u,p|
u == 'admin' && p == YOURPASSWORD
end
namespace 'metrics' do get do
{:clicks => Click.count} end
end
end
end
end
OAuth soon...
admin:<password>
>GET /api/v2/admin
>GET /api/v2/admin
401 Unauthorized
{“clicks”:1234}

44. Status/Error Codes
class MyAPI < Grape::API
helpers do
def current_user
@current_user ||= User.find_by_single_use_token(params[:auth_token])
end
end
get '/self' do
error!("401 Unauthorized", 401) unless current_user
current_user
end
end

45. Status/Error Codes
class MyAPI < Grape::API
helpers do
def current_user
@current_user ||= User.find_by_single_use_token(params[:auth_token])
end
end
get '/self' do
error!("401 Unauthorized", 401) unless current_user
current_user
end
end
>GET /self?auth_token=BAD

46. Status/Error Codes
class MyAPI < Grape::API
helpers do
def current_user
@current_user ||= User.find_by_single_use_token(params[:auth_token])
end
end
get '/self' do
error!("401 Unauthorized", 401) unless current_user
current_user
end
end
>GET /self?auth_token=BAD
401 Unauthorized

47. Demo
• Extractinator