Clean Architecture - Arena TOTVS 2015

Transcript

1. CLEAN ARCHITECTURE ON RAILS
2. CHAPTER I What is Clean Architecture?
4. the PROBLEM
6. your top level structure is screaming the web FRAMEWORK
7. The web is a delivery mechanism
8. the web is a COMMODITY
9. yet it DOMINATES your code
10. image you’ve just joined a PROJECT
13. what makes a GOOD architecture?
14. it is not about frameworks and tools
15. Fabiano Beselga CTO magnetis.com.br WRITER medium.com/@fbzga TWITTER @fbzga
16. bit.ly/clean-rails
17. IVAR JACOBSON
18. business rules INTERACTORS (aka use cases)
19. domain model ENTITIES
20. communication interfaces BOUNDARIES
21. diagrams: Robert C Martin
27. What about MVC?
28. MVC as a Web architecture
29. this is NOT WHAT I MEANT
30. WEB FRAMEWORK APP
31. CHAPTER II HOW to use it with Rails?
32. BRAAVOS
34. WE ARE OPENING A BANK! WE NEED TO HIRE A GREAT DEVELOPER!
36. WHAT ABOUT THIS ONE?
40. HIRED!
41. first day at WORK
42. THE SYSTEM MUST TRANSFER MONEY BETWEEN THE FAMILIES ACCOUNTS
43. OK! ANY EXCEPTION COURSES?
44. WHEN THERE ISN’T ENOUGH MONEY TO TRANSFER.
45. that’s easy, I can do it in 7 STEPS!
46. GREAT! YOU HAVE 10 MINUTES!
47. challenge accepted!
48. 1 create the PROJECT
49. rails new braavos
50. mkdir core
51. module Core end core.rb
52. 2 define BOUNDARIES
53. README Driven Development
54. Usage Transfer money Core.transfer_money(amount: 10_000, source_account_id: 1, destination_account_id: 2) README => true # when transfer successful => false # when not enough balance
55. 3 define behaviour Driven Development
56. context 'enough money to transfer' do it 'responds true' do expect(transfer).to be true end it 'debits the source account' do expect{ transfer }.to change{ source_account_balance }.by(- amount) end it 'credits the destination account' do expect{ transfer }.to change{ destination_account_balance }.by(amount) end end PRIMARY course
57. context 'not enough money to transfer' do it 'cancels the transfer and responds false' do expect(transfer).to be false end it 'does not change the accounts balance' do expect{ transfer }.to_not change{ source_account_balance } expect{ transfer }.to_not change{ destination_account_balance } end end EXCEPTION COURSE
58. FFF
59. define DATA MODEL 4
60. CAN YOU TELL ME A LITTLE MORE ABOUT THE DOMAIN?
61. EACH FAMILY HAS AN ACCOUNT. EACH ACCOUNT HAS A HISTORY OF TRADES MADE.
62. rails g model account name rails g model trade account:references amount:decimal date:date
63. trades debit: -1000 credit: +1000
64. the ENTRY POINT 5
65. module Core class << self delegate :transfer_money, to: TransferMoney end end core.rb
66. the USE CASE 6
67. module Core class TransferMoney def self.transfer_money(source_account_id:, destination_account_id:, amount:) balance = Core.get_balance(account_id: source_account_id) return false if balance < amount ActiveRecord::Base.transaction do Trade.create!(account_id: source_account_id, amount: -amount) Trade.create!(account_id: destination_account_id, amount: amount) end end end end core/transfer_money.rb
68. …
69. REFACTOR!
70. module Core class << self delegate :transfer_money, to: TransferMoney end end core.rb before
71. CAZE DSL to elegantly declare use cases
72. Gemfile gem 'caze'
73. module Core include Caze has_use_case :transfer_money, TransferMoney end core.rb AFTER
74. module Core include Caze has_use_case :transfer_money, TransferMoney, transactional: true end core.rb AFTER
75. g github.com/magne/s/caze
76. BREAKING NEWS! 
 WE HAVE MONEY TO HIRE AGAIN!
77. WHAT ABOUT THIS SNOW?
78. WHAT?
81. Usage Transfer money Core.transfer_money(amount: 10_000, source_account_id: 1, destination_account_id: 2) README => true # when transfer successful => false # when not enough balance
83. expose it to the web 7
84. let’s call it on a CONTROLLER
85. class TransferMoneyController < ApplicationController before_action :load_balance def create if Core.transfer_money(source_account_id: source_account_id, destination_account_id: destination_account_id, amount: amount) redirect_to new_transfer_money_path else flash[:error] = 'Not enough money on the source account' render :new end end private def load_balance @balance = Core.get_balance(account_id: current_account_id) end end
87. bit.ly/braavos
88. what just happened?
89. Core represents WHAT THE SYSTEM Does CHANGES
90. core/ get_balance.rb transfer_money.rb BEHAVIOUR CHANGES
91. the models represent WHAT THE SYSTEM IS STABLE
92. app/ models/ account.rb trade.rb DATA STABLE
93. a key, longstanding hallmark of a good program is that it separates what is stable from what changes in the interest of good maintenance. - Trygve Reenskaug
94. Models Core Rails delivery mechanism behaviour MODULE data #1
95. the ALTERNATIVES
96. Models Core Rails delivery mechanism behaviour RAILS ENGINE #2
97. The database is a detail
98. Isolate it!
99. Models Core Rails delivery mechanism behaviour gem rails engine data API #3
100. what about real life?
101. magnetis.com.br
102. ~ 4 years old codebase
103. experimenting with clean architecture ~ 2 years
105. the first seeds magnetis core
106. a module for each DOMAIN CONCEPT
107. we have a module for investments recommendation Advisor
108. Advisor.recommend_investments(params)
110. we have a module for accounting Accountant
112. magnetis/ domain/ accountant/ advisor/
113. BOUNDED CONTEXTs Advisor Accountant Order Manager Account Manager Trader Pricing Backtesting
114. why not MICROSERVICES?
115. we also use the Rails WAY
116. FINAL CHAPTER when to use it?
117. YOUR PRODUCT
118. core business your product rails way clean architecture
119. Eric Evans Don’t try yo apply DDD to everything. Draw a context map and decide on where you will make a push for DDD and where you will not .
120. THE distance from the view
121. the domain logic is close to the view Rails way
122. the domain logic is far from the view Clean architecture
123. TIMING
124. image: Kent Beck
125. Lessons learned
126. no good
127. Over-engineering when the domain logic is close to the view
128. getting out of the rails conventions may be hard
129. the cool STUFF
130. defer decisions until the last responsible moment
131. it SCREAMS BEHAVIOR
132. decoupled business rules
133. tests RUNNING FASTER!
134. what makes a GOOD architecture?
135. CLEAN ARCHITECTURE HEXAGONAL ARCHITECTURE DOMAIN DRIVEN DESIGN DATA CONTEXT INTERACTION TRAILBLAZER
136. all these architectures have SIMILAR OBJECTIVES
137. Architecture is about Intent
138. Intent = what the SYSTEM DOES
139. reflect THE USER’S MENTAL MODEL in your architecture
140. domain as a 1st class citizen
141. ONE MORE THING…
144. we are hiring fabiano@magne/s.com.br magne/s.com.br/dev
145. Developer #1 Developer #2 The Boss The Mastermind Tio Roberto Domain Father Advisor Presenter CAST TYRION LANNISTER Jon SNOW SHERKLOCKS’ BROTHER IVAR JACOBSON UNCLE BOB ERIC EVANS ROBERT DUVAL FABIANO BESELGA by @fbzga