Taming Monoliths without Microservices - RubyConf AU 2019

https://kellysutton.com/2019/02/07/taming-monoliths-without-microservices-rubyconf-au.html

Transcript

1. TAMING MONOLITHS
   WITHOUT MICROSERVICES
   Kelly Sutton — Rubyconf AU 2019
   

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2. Overview
   I. About Me
   
   II. Breaking the Monolith
   
   III. Tactics
   
   IV. Wrap Up
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3. Part I:
   
   About Me
   

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4. About Me
   

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5. About Greta
   

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6. About Greta
   

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7. About Greta
   

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8. About Greta
   

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9. But that’s not why we’re here
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10. We’re here to talk about Rails
    projects that push the limits
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11. kellysutton.com
    

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12. Time Geography
    Money People
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13. Correctness > Performance
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14. What goes wrong,
    when things get too big
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15. Part II:
    
    Breaking the Monolith
    

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16. The Swamp
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18. kellysutton.com
    

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19. kellysutton.com
    

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20. The Swamp
    Payroll
    HR
    Benefits
    Infra
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21. “Let’s Extract a Service!”
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22. Photo by Thomas Halfmann
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23. The Swamp
    Payroll
    HR
    Benefits
    Infra
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24. The Swamp
    Payroll
    HR
    Benefits
    Infra
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25. The Swamp
    Payroll
    HR
    Benefits
    Infra
    HR v2
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26. The Swamp
    Payroll
    HR
    Benefits
    Infra
    HR v2
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27. The Swamp
    Payroll
    Old HR
    Benefits
    Infra
    HR v2
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28. But there is a better way
    

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29. kellysutton.com
    

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30. Employee
    HR Payroll
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31. Employee
    HR Payroll
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32. Employee
    HR Payroll
    employee.last_name
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33. HR Payroll
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34. HR Payroll
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35. HR Payroll
    Employee PayrollEmployee
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36. HR Payroll
    Employee PayrollEmployee
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37. HR Payroll
    Employee PayrollEmployee
    payroll_employee.last_name
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38. HR Payroll
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39. HR Payroll
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40. Value Objects
    HR Payroll
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41. Conceptual
    Compression
    

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42. Conceptual
    Expansion
    

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43. Part III:
    
    Tactics
    

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44. Recommendation #1
    
    Mind and Avoid Circular
    Dependencies
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45. As your Rails code base grows,
    question bidirectional relationships
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46. 1 # app/models/company.rb
    2 class Company < ApplicationRecord
    3 has_many :employees
    4 end
    5
    6 # app/models/employee.rb
    7 class Employee < ApplicationRecord
    8 belongs_to :company
    9 end
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47. 1 # app/models/company.rb
    2 class Company < ApplicationRecord
    3 has_many :employees
    4 end
    5
    6 # app/models/employee.rb
    7 class Employee < ApplicationRecord
    8 belongs_to :company
    9 end
    Do we need this?
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48. Company Employee
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49. Company Employee
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50. Recommendation #2
    
    Use Value Objects to
    Traverse Edges
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51. 1 # app/services/company_signed_up.rb
    2 class CompanySignedUp
    3 def self.call(company)
    4 CompanyMailer.welcome_email(company)
    5 StatsTracker.company_signed_up(company)
    6 end
    7 end
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52. 1 # app/services/company_signed_up.rb
    2 class CompanySignedUp
    3 def self.call(company)
    4 user_first_name = company.admin_first_name
    5 email = company.admin_email
    6
    7 CompanyMailer.welcome_email(email, user_first_name)
    8 StatsTracker.company_signed_up(company.id)
    9 end
    10 end
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53. Recommendation #3
    
    Avoid Callbacks
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54. 1 # app/models/company.rb
    2 class Company < ApplicationRecord
    3 after_create :send_update_email, if: :has_email?
    4
    5 private
    6
    7 def send_update_email
    8 CompanyMailer.welcome_email(self)
    9 end
    10 end
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55. Company CompanyMailer
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56. 1 # app/services/create_company.rb
    2 class CreateCompany
    3 def self.call(company_params)
    4 company = Company.create!(company_params)
    5
    6 CompanyMailer.welcome_email(company)
    7 end
    8 end
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57. Company CompanyMailer
    CreateCompany
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58. Recommendation #4
    
    Move slowly!
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59. Part IV:
    
    Wrap Up
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60. –Kent Beck
    “Make the hard change easy
    (this may be hard),
    then make the easy change.”
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61. Thanks!
    Slides and more available at kellysutton.com
    

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62. References
    • Bernhardt, Gary. “Boundaries.” 2012.
    
    • Bernhardt, Gary. “Functional Core, Imperative Shell.” 2012.
    
    • Evans, Eric. “Domain-Driven Design: Tackling Complexity in the Heart of Software.” 2003.
    
    • Fowler, Martin, et al. “Refactoring: Improving the Design of Existing Code.” 1999.
    
    • Feathers, Michael. “Working Effectively with Legacy Code.” 2004.
    
    • Hickey, Rich. “Simple Made Easy.” 2011.
    
    • Hickey, Rich. “The Value of Values.” 2012.
    
    • Scott, James C. “Seeing Like a State.” 1999.
    
    • Searls, Justin. “My Preferred Method of TDD.” 2017
    
    • Spolsky, Joel. “Things You Should Never Do, Part I.” 2006.
    

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63. Special Thanks
    • Noa Elad
    
    • Matan Zruya
    
    • Sihui Huang
    
    • Natalie Wong
    
    • Karlo Hoa
    
    • Amelie Meyer-Robinson
    
    • Quentin Balin
    

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