I've Made a Huge Mistake - GoRuCo 2018

How we got services wrong and what we learned along the way

Transcript

1. I’ve Made a Huge Mistake How we got services wrong and what we learned along the way Kelly Sutton — GoRuCo 2018
2. Overview I. About Me II. Breaking the Monolith III. 5 Sweet Tips IV. Wrap Up
3. Part I: About Me
4. About Me
5. About Greta
6. About Greta
7. About Greta
8. About Greta
9. But that’s not why we’re here
10. We’re here to talk about Rails projects that push the limits
12. Time Geography Money People
13. Correctness > Performance
14. So let’s talk about how things go wrong, and when things get too big
15. Part II: Breaking the Monolith
16. The Swamp
19. The Swamp Payroll HR Benefits Infra
20. “Let’s Extract a Service!”
21. Photo by Thomas Halfmann
22. The Swamp Payroll HR Benefits Infra
23. The Swamp Payroll HR Benefits Infra
24. The Swamp Payroll HR Benefits Infra HR v2
25. The Swamp Payroll HR Benefits Infra HR v2
26. The Swamp Payroll Old HR Benefits Infra HR v2
27. But there is a better way
29. Applications vs. Services
31. Applications vs. Services
32. Applications vs. Services Have their own process Might have their own process
33. Applications vs. Services Have their own process Might have their own process Have their own database Probably share a database
34. Applications vs. Services Have their own process Might have their own process Have their own database Probably share a database Scale independently Scales with the host app
35. Applications vs. Services Have their own process Might have their own process Have their own database Probably share a database Scale independently Scales with the host app Might be an another language Share the same language
36. The Swamp Payroll HR Benefits Infra
37. The Swamp Payroll HR Benefits Infra
38. The Swamp Payroll HR Benefits Infra
39. The Swamp Payroll HR Benefits Infra
40. The Swamp Payroll HR Benefits Infra
41. The Swamp Payroll HR Benefits Infra
42. The Swamp Payroll HR Benefits Infra
43. The Swamp Payroll HR Benefits Infra
44. The Swamp Payroll HR Benefits Infra
45. The Swamp Payroll HR Benefits Infra
46. The Swamp Payroll HR Benefits Infra
47. The Swamp Payroll HR Benefits Infra
48. Conceptual Compression
50. Conceptual Expansion
51. Part III: 5 Sweet Tips
52. Recommendation #1 Mind and Avoid Circular Dependencies
53. As your Rails code base grows, question bidirectional relationships
54. 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
55. 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?
56. Company Employee
57. Company Employee
58. Recommendation #2 Use Value Objects to Traverse Edges
59. 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
60. 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
61. Recommendation #3 Avoid Callbacks
62. 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
63. Company CompanyMailer
64. 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
65. Company CompanyMailer CreateCompany
66. Recommendation #4 Extract Services first, then extract Applications
67. Recommendation #5 Move slowly!
68. Part IV: Wrap Up
69. –Kent Beck “Make the hard change easy (this may be hard), then make the easy change.”
70. Thanks! Slides and more available at kellysutton.com
71. 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. • 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.
72. Special Thanks • Noa Elad • Matan Zruya • Sihui Huang • Natalie Wong • Karlo Hoa • Amelie Meyer-Robinson • Quentin Balin