Service Oriented Design in Practice

Implementing a Service Oriented Design with Ruby can lower maintenance costs by increasing isolation, scalability and code reuse. That's the theory, anyway. It's true, but in practice there are lots of nitty gritty details of rolling out a service oriented design that can reduce the expected benefits -- or even leave you worse off than you started.

This talk will shed light on what it takes to successfully leverage a service oriented architecture. Emphasis will be on less discussed considerations like testing strategies, dependency and release management, operations and developer tools rather than the happy path of how to implement and consume services. Examples will be provided from our experience building tool to analyze home energy use in order to help people save on their power bills.

In the end, you'll walk away with a deeper understanding of how to weigh the pros and cons of introducing services into your architecture, and you'll have learned some techniques to make the transition smoother if you decide it's right for you.

Transcript

1. Service Oriented Design in Practice Bryan Helmkamp • MountainWest RubyConf • March 17, 2011
2. Bryan Helmkamp @brynary bryan@brynary.com
4. SOD? http://www.flickr.com/photos/darksidex/224432111
6. “SOA has become a loaded term. To [many], it implies the use of tools such as SOAP, WSDL, WS-*, or XML-RPC. This [is why we use] the word design as opposed to architecture.”
7. What’s the point?
8. “Never trust a programmer who says he knows C++” http://lbrandy.com/blog/2010/03/never-trust-a-programmer-who-says-he-knows-c/
10. SOD is a “two peak” concept
11. OOP and SRP for systems! Designer can’t boot app What’s causing this bug?!? Copy/pasted all deploy scripts We need some rules (and tools) Broke production, tests are green The tests are now a pain to run! Enlightenment?
12. E2.0 architecture: Then
13. App Bill Collector Calculator Weather RabbitMQ
14. E2.0 architecture: Now
15. App Calculator Weather
16. SOD Benefits • Isolation • Robustness • Scalability • Agility • Interoperability • Reuse
17. Why did we use services?
19. Five Problems • Designer can’t boot app • Copy/pasted all deploy scripts • What’s causing this bug?!? • Broke production, tests are green • The tests are now a pain to run!
20. Four Areas • Local development • Deployment • Operations • Testing
21. Our designer can’t run the app anymore!
22. One-command boot
23. $  e20  start
24. e20_cli
25. e20  tail e20  clone e20  pull e20  status e20  disable e20  enable e20  inventory e20  bundle e20  configure e20  migrate e20  bootstrap e20  start e20  stop e20  reset
26. Thor
27. We just copied/ pasted all our deploy scripts!
28. Package deploy scripts into a gem
29. e20_cap
30. e20_cap.gemspec lib lib/e20 lib/e20/recipes lib/e20/recipes/bundler.rb lib/e20/recipes/database.rb lib/e20/recipes/defaults.rb lib/e20/recipes/dj.rb lib/e20/recipes/gem.rb lib/e20/recipes/notify.rb lib/e20/recipes/resque.rb lib/e20/recipes/symlinks.rb lib/e20/recipes/unicorn.rb lib/e20/recipes/whenever.rb lib/e20/recipes.rb Rakefile README.rdoc
31. load  'deploy'  #  Capistrano's  default  tasks gem  "e20_cap",  "0.10.0" require  "e20/recipes" require  "e20/recipes/whenever" set  :application,  "weather_service" set  :auto_tagger_stages,  [:staging,  :production] set  :hoptoad_api_key,  "[key  here]" task  :production  do    set  :rails_env,  'production'    set  :auto_tagger_stage,  :production    role  :app,  "app01-­‐weather.prod"    role  :unicorn,  "app01-­‐weather.prod"    role  :cron,  "app01-­‐weather.prod" end
32. What’s causing this bug?!?
33. Need more introspection
34. e20_ops_middleware
35. $  curl  -­‐I  http://calc.stage/v0/users/foo HTTP/1.1  404  Not  Found Server:  nginx Date:  Tue,  15  Mar  2011  04:01:11  GMT Content-­‐Type:  application/json;  charset=utf-­‐8 Transfer-­‐Encoding:  chunked Connection:  close Status:  404  Not  Found X-­‐Transaction:  74b471a589084c4a9020a8eaddbfac X-­‐Served-­‐By:  app02-­‐calc.stage X-­‐Revision:  f46e3f13668f320bd3bd8e1e7e9377b9c Cache-­‐Control:  no-­‐cache
36. $  curl  -­‐I  http://calc.stage/v0/users/foo HTTP/1.1  404  Not  Found Server:  nginx Date:  Tue,  15  Mar  2011  04:01:11  GMT Content-­‐Type:  application/json;  charset=utf-­‐8 Transfer-­‐Encoding:  chunked Connection:  close Status:  404  Not  Found X-­‐Transaction:  74b471a589084c4a9020a8eaddbfac X-­‐Served-­‐By:  app02-­‐calc.stage X-­‐Revision:  f46e3f13668f320bd3bd8e1e7e9377b9c Cache-­‐Control:  no-­‐cache
37. $  curl  -­‐I  http://calc.stage/v0/users/foo HTTP/1.1  404  Not  Found Server:  nginx Date:  Tue,  15  Mar  2011  04:01:11  GMT Content-­‐Type:  application/json;  charset=utf-­‐8 Transfer-­‐Encoding:  chunked Connection:  close Status:  404  Not  Found X-­‐Transaction:  74b471a589084c4a9020a8eaddbfac X-­‐Served-­‐By:  app02-­‐calc.stage X-­‐Revision:  f46e3f13668f320bd3bd8e1e7e9377b9c Cache-­‐Control:  no-­‐cache
38. $  curl  -­‐I  http://calc.stage/v0/users/foo HTTP/1.1  404  Not  Found Server:  nginx Date:  Tue,  15  Mar  2011  04:01:11  GMT Content-­‐Type:  application/json;  charset=utf-­‐8 Transfer-­‐Encoding:  chunked Connection:  close Status:  404  Not  Found X-­‐Transaction:  74b471a589084c4a9020a8eaddbfac X-­‐Served-­‐By:  app02-­‐calc.stage X-­‐Revision:  f46e3f13668f320bd3bd8e1e7e9377b9c Cache-­‐Control:  no-­‐cache
39. Open Source https://github.com/efficiency20/ops_middleware
40. Detailed logging
41. Started  GET  "/rewards"  at  Mon  Mar  14  21:06:41   -­‐0700  2011 [E20::Ops::Middleware]  Transaction  ID:   5c47dc12-­‐0cb1-­‐4aae-­‐82e8-­‐4c9a58a33ca4    Processing  by  RewardsController#show  as  HTML [Calc]  GET  http://calc.prod/users/... [Calc]  200  from  app02-­‐calc.prod  (b010ea1b)  :   5199d9b3-­‐47bf-­‐491c-­‐bef0-­‐d591390a07a8 Rendered  rewards/show.html.haml  (39.4ms) Completed  200  OK  in  58ms
42. Started  GET  "/rewards"  at  Mon  Mar  14  21:06:41   -­‐0700  2011 [E20::Ops::Middleware]  Transaction  ID:   5c47dc12-­‐0cb1-­‐4aae-­‐82e8-­‐4c9a58a33ca4    Processing  by  RewardsController#show  as  HTML [Calc]  GET  http://calc.prod/users/... [Calc]  200  from  app02-­‐calc.prod  (b010ea1b)  :   5199d9b3-­‐47bf-­‐491c-­‐bef0-­‐d591390a07a8 Rendered  rewards/show.html.haml  (39.4ms) Completed  200  OK  in  58ms
43. Started  GET  "/rewards"  at  Mon  Mar  14  21:06:41   -­‐0700  2011 [E20::Ops::Middleware]  Transaction  ID:   5c47dc12-­‐0cb1-­‐4aae-­‐82e8-­‐4c9a58a33ca4    Processing  by  RewardsController#show  as  HTML [Calc]  GET  http://calc.prod/users/... [Calc]  200  from  app02-­‐calc.prod  (b010ea1b)  :   5199d9b3-­‐47bf-­‐491c-­‐bef0-­‐d591390a07a8 Rendered  rewards/show.html.haml  (39.4ms) Completed  200  OK  in  58ms
44. Started  GET  "/rewards"  at  Mon  Mar  14  21:06:41   -­‐0700  2011 [E20::Ops::Middleware]  Transaction  ID:   5c47dc12-­‐0cb1-­‐4aae-­‐82e8-­‐4c9a58a33ca4    Processing  by  RewardsController#show  as  HTML [Calc]  GET  http://calc.prod/users/... [Calc]  200  from  app02-­‐calc.prod  (b010ea1b)  :   5199d9b3-­‐47bf-­‐491c-­‐bef0-­‐d591390a07a8 Rendered  rewards/show.html.haml  (39.4ms) Completed  200  OK  in  58ms
45. Started  GET  "/rewards"  at  Mon  Mar  14  21:06:41   -­‐0700  2011 [E20::Ops::Middleware]  Transaction  ID:   5c47dc12-­‐0cb1-­‐4aae-­‐82e8-­‐4c9a58a33ca4    Processing  by  RewardsController#show  as  HTML [Calc]  GET  http://calc.prod/users/... [Calc]  200  from  app02-­‐calc.prod  (b010ea1b)  :   5199d9b3-­‐47bf-­‐491c-­‐bef0-­‐d591390a07a8 Rendered  rewards/show.html.haml  (39.4ms) Completed  200  OK  in  58ms
46. Started  GET  "/rewards"  at  Mon  Mar  14  21:06:41   -­‐0700  2011 [E20::Ops::Middleware]  Transaction  ID:   5c47dc12-­‐0cb1-­‐4aae-­‐82e8-­‐4c9a58a33ca4    Processing  by  RewardsController#show  as  HTML [Calc]  GET  http://calc.prod/users/... [Calc]  200  from  app02-­‐calc.prod  (b010ea1b)  :   5199d9b3-­‐47bf-­‐491c-­‐bef0-­‐d591390a07a8 Rendered  rewards/show.html.haml  (39.4ms) Completed  200  OK  in  58ms
47. Started  GET  "/rewards"  at  Mon  Mar  14  21:06:41   -­‐0700  2011 [E20::Ops::Middleware]  Transaction  ID:   5c47dc12-­‐0cb1-­‐4aae-­‐82e8-­‐4c9a58a33ca4    Processing  by  RewardsController#show  as  HTML [Calc]  GET  http://calc.prod/users/... [Calc]  200  from  app02-­‐calc.prod  (b010ea1b)  :   5199d9b3-­‐47bf-­‐491c-­‐bef0-­‐d591390a07a8 Rendered  rewards/show.html.haml  (39.4ms) Completed  200  OK  in  58ms
48. Started  GET  "/rewards"  at  Mon  Mar  14  21:06:41   -­‐0700  2011 [E20::Ops::Middleware]  Transaction  ID:   5c47dc12-­‐0cb1-­‐4aae-­‐82e8-­‐4c9a58a33ca4    Processing  by  RewardsController#show  as  HTML [Calc]  GET  http://calc.prod/users/... [Calc]  200  from  app02-­‐calc.prod  (b010ea1b)  :   5199d9b3-­‐47bf-­‐491c-­‐bef0-­‐d591390a07a8 Rendered  rewards/show.html.haml  (39.4ms) Completed  200  OK  in  58ms
49. The app is broken, but the tests are green!
50. What’s happening?
51. Service Application Client
52. Service Application Client Interfaces Break
53. What can we do about it?
54. Prerequisite: Version the client with the service
56. 1. Test the client with the service
57. Service Application Client
58. describe  Calculator::User,  "#bills"  do    before  {  Artifice.activate_with(Rails.application)  }    after    {  Artifice.deactivate  }    it  "returns  all  bills  for  the  user"  do        user  =  User.make        1.upto(3)  do  |n|            @user.bills.make(:date  =>  n.months.ago)        end        Calculator::User.new(user.id).should  have(3).bills    end end
59. 2. Test the app with test doubles
60. Service Application Client
61. describe  Notifications,  ".send_monthly_status"  do    it  "includes  the  kWh  in  the  email"  do        user  =  User.new        points  =  MonthlyUsagePointsAward.new(            :user  =>  user,            :bill  =>  mock(:electricity  =>  100)        )        Notifications.send_monthly_status(points)        email  =  ActionMailer::Base.deliveries.last        email.subject.should  ==  "You  used  100  kWh."    end end
62. describe  Notifications,  ".send_monthly_status"  do    it  "includes  the  kWh  in  the  email"  do        user  =  User.new        points  =  MonthlyUsagePointsAward.new(            :user  =>  user,            :bill  =>  mock(:electricity  =>  100)        )        Notifications.send_monthly_status(points)        email  =  ActionMailer::Base.deliveries.last        email.subject.should  ==  "You  used  100  kWh."    end end
63. 3. Test the full stack
64. Service Application Client
65.    Scenario:  Sort  actions  by  recommendation        Given  I  live  in  zip  code  "60608"        When  I  view  my  recommended  actions        Then  the  first  three  actions  should  be:          |  Install  a  tankless  water  heater        |          |  Reduce  water  heater  temperature        |          |  Replace  your  home  lights  with  CFLs  |
66. Service Application Client
67. Avoid: FakeWeb
68. The tests are now a pain to run!
69. The Testing Pyramid
70. Units/objects GUI Integration
71. 100 unit tests + 10 integration tests + 1 UI test
72. Continuous Improvement
73. Root Cause Analysis
74. Proportional investment
75. “Development is production”
76. Key learnings
77. Many hidden costs of services
78. Can still be worth it
79. Like everything, moderation is key
80. Address friction as it occurs
81. YMMV
82. Thank you @brynary bryan@brynary.com