Context-Driven Development: Architecture your code with Phoenix context

Presented at 2021 ElixirConf by Jenny Shih

Note: There are quite a few gifs in the slides. They can be only uploaded as still images so some effects are gone, but that doesn't affect the values this presentation wants to convey.

1. @jenny_codes Context-Driven Development Architect your Code with Phoenix Context
4. https://media.giphy.com/media/NWtFdrEXGwZX2/giphy.gif
5. • Quick onboarding
6. • Quick onboarding • Effective
7. • Quick onboarding • Effective • Using Elixir
8. https://twitter.com/DJTGIF/status/856856284892729345 Context
9. What do I do with contexts?
10. Outline • The cunning challenges of contexts • The quest, and what did not work • Build-your-own architecture • Revisit contexts • Context-driven development
11. Outline • The cunning challenges of contexts • The quest, and what did not work • Build-your-own architecture • Revisit contexts • Context-driven development
13. “Contexts are dedicated modules that expose and group related functionality.“
14. Model Controller View Request Response
15. Model Controller View /your_app_web /your_app
16. Phoenix MVC structure lib ├── your_app ├── your_app_web Model Controller View /your_app_web /your_app
17. Phoenix MVC structure lib ├── your_app ├── your_app_web ├── controllers ├── endpoint.ex ├── router.ex ├── templates └── views Model Controller View /your_app_web /your_app
18. Phoenix MVC structure lib ├── your_app ├── ??? ├── ??? └── ??? ├── your_app_web Model Controller View /your_app_web /your_app
19. Phoenix MVC structure lib ├── your_app ├── ??? ├── ??? └── ??? ├── your_app_web Model Controller View /your_app_web /your_app Context
20. The cunning challenges of contexts
21. The cunning challenges of contexts • Different layers of concerns are mixed together.
24. The cunning challenges of contexts
25. concept of context Ecto business logic juggler by Orin zuu from the Noun Project The cunning challenges of contexts
26. The cunning challenges of contexts • Different layers of concerns are mixed together. • Relationships between components are ambiguous.
27. from Phoenix of fi cial guide “Sometimes it may be tricky to determine if two resources belong to the same context or not. In those cases, prefer distinct contexts per resource and refactor later if necessary. “ The cunning challenges of contexts
28. Outline • The cunning challenges of contexts • The quest, and what did not work • Build-your-own architecture • Revisit contexts • Context-driven development
29. What to do with context? • Look at open-source projects?
30. What to do with context? • Look at open-source projects? • Domain Driven Design?
31. source: https://youtu.be/tMO28ar0lW8
32. https://gfycat.com/elderlyhatefulhornet Challenge accepted.
33. https://www.domainlanguage.com/wp-content/uploads/2016/05/DDD_Reference_2015-03.pdf
35. https://gfycat.com/composedimportantavians
36. 💡
37. https://gph.is/g/4zqknpn?tc=1 via @giphy architecture
38. from Phoenix of fi cial guide “Contexts are dedicated modules that expose and group related functionality.“
39. Outline • The cunning challenges of contexts • The quest, and what did not work • Build-your-own architecture • Revisit contexts • Context-driven development
40. How do I build an application?
41. Use case Adapter Infrastructure Domain
42. Adapter Infrastructure Domain Use case • Business logic • Free of technology
43. Use case Adapter Infrastructure Domain • Use case orchestration • Transaction management
44. Use case Adapter Infrastructure Domain • Translation
45. Use case Adapter Infrastructure Domain • External dependency • Technical details
46. Adapter Use case Infrastructure Domain
47. Clean architecture file structure lib ├── domain ├── use_case ├── adapter └── infrastructure
48. Clean architecture file structure lib ├── domain ├── use_case ├── adapter └── infrastructure ├── model ├── store (interface) └── service
49. Clean architecture file structure lib ├── domain ├── use_case ├── adapter └── infrastructure ├── upload_image.ex └── register_user.ex
50. Clean architecture file structure lib ├── domain ├── use_case ├── adapter └── infrastructure ├── cli.ex ├── web └── store
51. Clean architecture file structure lib ├── domain ├── use_case ├── adapter └── infrastructure ├── cli.ex ├── web └── store
52. Clean architecture file structure lib ├── domain ├── use_case ├── adapter └── infrastructure ├── cli.ex ├── web └── store
53. Clean architecture file structure lib ├── domain ├── use_case ├── adapter └── infrastructure ├── application.ex ├── mailer.ex ├── repo.ex ├── web ├── endpoint.ex ├── gettext.ex ├── router.ex └── telemetry.ex
54. (Revisit) The cunning challenges of contexts • Different layers of concerns are mixed together. • Relationships between components are ambiguous.
55. • Different layers of concerns are mixed together. Separation of concerns 👍 • Relationships between components are ambiguous.
56. • Different layers of concerns are mixed together. Separation of concerns 👍 • Relationships between components are ambiguous. Clear relationship between components 👍
57. • Different layers of concerns are mixed together. Separation of concerns 👍 • Relationships between components are ambiguous. Clear relationship between components 👍 • Very testable 👍
58. The almighty clean architecture • Separation of concerns • Clear relationship between components • Very testable
59. https://media.giphy.com/media/jQnrJSmFB6KVQ7kfpK/giphy.gif
60. Outline • The cunning challenges of contexts • The quest, and what did not work • Build-your-own architecture • Revisit contexts • Context-driven development
61. from Phoenix of fi cial guide “Contexts are dedicated modules that expose and group related functionality.“
62. How can context improve our current architecture?
63. Example: User noti fi cation Use case Adapter Infrastructure Domain
64. Adapter Infrastructure Domain Use case • model/noti fi cation.ex • store/noti fi cation_store.ex • store/user_store.ex Example: User noti fi cation
65. Use case Adapter Infrastructure Domain • notify_user.ex Example: User noti fi cation
66. Use case Adapter Infrastructure Domain • store/user_store.ex • store/noti fi cation_store.ex • web/controller/ noti fi cation_controller.ex Example: User noti fi cation
67. Improve current architecture with context • domain/model/noti fi cation.ex • domain/store/noti fi cation_store.ex • domain/store/user_store.ex • use_case/notify_user.ex • adapter/store/noti fi cation_store.ex • adapter/store/user_store.ex • adapter/web/controller/noti fi cation_controller.ex
68. • domain/model/noti fi cation.ex • domain/store/noti fi cation_store.ex • domain/store/user_store.ex • use_case/notify_user.ex • adapter/store/noti fi cation_store.ex • adapter/store/user_store.ex • adapter/web/controller/noti fi cation_controller.ex Improve current architecture with context
69. • domain/model/noti fi cation.ex • domain/model/user.ex • domain/store/noti fi cation_store.ex • domain/store/user_store.ex • use_case/notify_user.ex • adapter/store/noti fi cation_store.ex • adapter/store/user_store.ex • adapter/web/controller/noti fi cation_controller.ex Improve current architecture with context
70. • domain/model/noti fi cation.ex • domain/model/user.ex • domain/store/noti fi cation_store.ex • domain/store/user_store.ex • use_case/notify_user.ex • adapter/store/noti fi cation_store.ex • adapter/store/user_store.ex • adapter/web/controller/noti fi cation_controller.ex Improve current architecture with context
71. Adapter Use case Infrastructure Domain
72. Adapter Use case Infrastructure Domain
73. Apply context Adapter Use case Infrastructure Domain
74. Apply contexts Adapter Use case Infrastructure Domain External Internal
75. Apply contexts Adapter Use case Infrastructure Domain External Internal
76. Apply contexts Internal Use case Domain
77. Apply contexts Internal Use case Domain Context
78. Apply contexts Use case Domain Context YourApp.[Context] YourApp.[Context].[UseCase] YourApp.[Context].[Domain]
79. Apply contexts Use case Domain Context Noti fi cation Noti fi cation.notify_user Noti fi cation.Noti fi cation Noti fi cation.UserStore Noti fi cation.Noti fi cationStore
80. Apply contexts Use case Domain Context Noti fi cation Noti fi cation.notify_user Noti fi cation.Noti fi cation Noti fi cation.UserStore Noti fi cation.Noti fi cationStore
81. Apply contexts Use case Domain Context Noti fi cation Noti fi cation.notify_user Noti fi cation.Noti fi cation Noti fi cation.UserStore Noti fi cation.Noti fi cationStore
82. Apply contexts Use case Domain Context Noti fi cation Noti fi cation.notify_user Noti fi cation.Noti fi cation Noti fi cation.UserStore Noti fi cation.Noti fi cationStore
83. File structure ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex
84. File structure ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex # context
85. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
86. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
87. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
88. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
89. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
90. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
91. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
92. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
93. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
94. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex File structure
95. ElixirLab Noti fi cation Account Cross-context relationship
96. ElixirLab Noti fi cation Account Account.create_user Noti fi cation.not fi y_new_user Cross-context relationship
97. ElixirLab Noti fi cation Account Cross-context relationship: Implicit dependency? depends on
98. ElixirLab Noti fi cation Account Cross-context relationship depends on depends on
99. ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex The external layer
100. elixir_lab ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex The external layer
101. elixir_lab ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex elixir_lab_external ├── noti fi cation_store.ex ├── repo │ ├── schema │ └── user_repo.ex ├── web (Phoenix) The external layer
102. elixir_lab ├── noti fi cation │ ├── noti fi cation.ex │ ├── noti fi cation_store.ex │ └── user_store.ex └── noti fi cation.ex elixir_lab_external ├── noti fi cation_store.ex ├── repo │ ├── schema │ └── user_repo.ex ├── web (Phoenix) The external layer
103. • Separation of concerns • Clear relationship between components • Very testable Result of applying context
104. • Separation of concerns • Clear relationship between components • Very testable • Groups related functionality together 👍 Result of applying context
105. Outline • The cunning challenges of contexts • The quest, and what did not work • Build-your-own architecture • Revisit contexts • Context-driven development 🏁
106. Context-driven development • Separate your business concerns.
107. Context-driven development • Separate your business concerns. • Take advantage of Elixir’s fl exibility.
108. Context-driven development • Separate your business concerns. • Take advantage of Elixir’s fl exibility. • But use it carefully.
109. Context-driven development • Separate your business concerns. • Take advantage of Elixir’s fl exibility. • But use it carefully. • Make your architecture scream.
110. source: https://tenor.com/view/chubby-chubby-cat-stuck-door-pet-door-gif-5518148 Phoenix Your application
111. source: http://gph.is/1eeJ98k?tc=1 Phoenix Your application
112. Resources Books • Clean Architecture: A Craftsman's Guide to Software Structure by Robert C. Martin • Functional Web Development with Elixir, OTP, and Phoenix by by Lance Halvorsen • Domain Modeling Made Functional by Scott Wlaschin • Implementing Domain-Driven Design by Vaughn Vernon • Programming Phoenix by Bruce Tate, Chris McCord and José Valim
113. Resources Videos • Building Beautiful Systems with Phoenix Contexts and DDD by Andrew Hao • Lonestar ElixirConf 2017- KEYNOTE: Phoenix 1.3 by Chris McCord • Ruby Midwest 2011 - Keynote: Architecture the Lost Years by Robert Martin
114. Resources Articles / Blog posts / Forum questions • https://hexdocs.pm/phoenix/contexts.html • https://elixirforum.com/t/hexagonal-architecture-in-elixir/32225/16 • https://elixirforum.com/t/how-to-determine-contexts-with-phoenix-1-3/4367 • https://aaronrenner.io/2019/09/18/application-layering-a-pattern-for-extensible- elixir-application-design.html • https://www.destroyallsoftware.com/screencasts/catalog/functional-core- imperative-shell • https://blog.cleancoder.com
115. https://github.com/jenny-codes/elixirlab @jenny_codes