How to rewrite, a bit at a time

Domain-Driven Design Europe 2019

Transcript

1. How to rewrite, a bit at a time Sabrina Leandro @saleandro Domain-Driven Design Europe 2019
2. Rewrites at Songkick
3. Rewrites at Songkick 1. Songkick.com
4. Rewrites at Songkick 1. Songkick.com 2. Tickets store
5. Rewrites at Songkick 1. Songkick.com 2. Tickets store 3. Internal tools
6. BIG REWRITE STRIKES AGAIN
7. BIG REWRITE STRIKES AGAIN
8. • The problem • How to start a rewrite project • How to run it • How to finish it • How to not need it again! This talk
9. Stop me if you think you’ve heard this one before The problem
10. 10101 11001
11. 10101 11001 10101110011010 11100110011100 11100111001100 11100111001110 00101011100111 00111001
12. Software Entropy 10101 11001 10101110011010 11100110011100 11100111001100 11100111001110 00101011100111 00111001
13. Complex abstractions Lots of features Too many slow tests Little to no tests No clear abstractions Lots of features
14. Complex abstractions Lots of features Too many slow tests Little to no tests No clear abstractions Lots of features Tickets store & Internal tools
15. Complex abstractions Lots of features Too many slow tests Little to no tests No clear abstractions Lots of features Songkick.com Tickets store & Internal tools
17. How to start it
18. •Is it the right time? •Is it the right reason?
19. Is it the right time? Discovery vs Delivery
20. Is it the right time? Yes, if the product has a clear business value today.
21. Is it the right reason? What difference does it make?
22. Is it the right reason? Yes, if there’s one clear business case.
23. PLEASE PLEASE PLEASE Let me get what I want
24. How to sell it Have one clear business case
25. How to sell it Show what a great new world it will be!
26. How to sell it Find allies outside of your team
27. Make the pain visible How to sell it
28. How to sell it Do Repeat Yourself
29. How to sell it Do Repeat Yourself Do Repeat Yourself
30. How to run it
31. Technical vision and strategy Now The future! ???
32. Technical vision and strategy Now The future!
33. Technical vision and strategy Now The future! Steps to get there ???
34. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application
35. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application
36. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application Legacy application
37. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application
38. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application Legacy application
39. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application Legacy application New application
40. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New New application Legacy application Legacy application New application
41. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New New application Legacy application Legacy application RIP Legacy application New application
42. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New New application VALUE Legacy application Legacy application RIP Legacy application New application
43. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application Legacy application New application
44. Now Bright future! Team 2: Building new application Rewrite from scratch Legacy application Team 1: Maintaining legacy application New Legacy application Legacy application New application Legacy application
45. “Rewrite from scratch: Waterfall process of rewrites
46. The strangler application
47. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
48. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
49. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
50. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
51. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
52. Team 1: Maintaining legacy and building new application Now Bright future! Rewrite using strangler
53. Team 1: Maintaining legacy and building new application New applicati Now Bright future! Rewrite using strangler
54. Team 1: Maintaining legacy and building new application New applicati Now Bright future! Rewrite using strangler
55. Team 1: Maintaining legacy and building new application New applicati Now Bright future! Rewrite using strangler
56. Team 1: Maintaining legacy and building new application New applicati Now Bright future! Rewrite using strangler
57. Team 1: Maintaining legacy and building new application New applicati VALUE! Now Bright future! Rewrite using strangler
58. /orders /customers
59. /orders /customers new/customers
60. /orders /customers
61. /orders /customers Build Validate Replace Delete Repeat
63. “ Deleting is faster than rewriting
64. Cut features to move faster Must haves Should haves Won’t haves
65. Must haves: main proposition Should haves: if there’s time Won’t haves: remove completely Cut features to move faster
66. “ If we were starting over, what would we build today, knowing what we know now?
67. During the project
68. How to run it Do one thing at a time
69. 1. Find the biggest blocker 2. Remove it completely 3. Repeat How to run it Warning: Step 2 might involve more than coding
70. How to run it Celebrate your successes!
75. That joke isn’t funny anymore… How to run it Do Repeat Yourself, again
76. How to finish it
77. How to finish it I started something I couldn’t finish
78. How to finish it These things 
 take time
79. How to not need it again
80. 10101 11001 10101110011010 11100110011100 11100111001100 11100111001110 001010111 Time… Software Entropy
81. How to not need it again Make the cost visible
83. DELETE
84. DELETE CODE
85. DELETE CODE FEATURES
86. DELETE CODE FEATURES PRODUCTS
87. “ If we were starting over, what would we build today, knowing what we know now?
88. Make it part of your day-to-day How to not need it again
89. “ A refactor a day keeps the rewrite away!
90. How to not need it again A little bit and often
91. How to not need it again Get used to inconsistencies
92. Technical migrations Continuously deliver value Delete what’s not valuable One business goal
93. Sustainable Software Make maintenance cost visible Learn and collaborate Refactor a little bit and often
94. Thanks! Sabrina, take a bow… sabrina@saleandro.com @saleandro
95. Bigmouth Strikes Again This Charming Man Stop Me If You Think You’ve Heard This One Before What Difference Does It Make? Please, Please, Please, Let Me Get What I Want That Joke Isn’t Funny Anymore I Started Something I Couldn’t Finish These Things Take Time Sheila Take A Bow Thanks! Sabrina, take a bow… sabrina@saleandro.com @saleandro
96. Songkick.com rewrite • https://devblog.songkick.com/the-path-to-soa-d986a18d4a8b • https://devblog.songkick.com/our-object-based-rails-frontend-3e2ddc048d12 • https://www.youtube.com/watch?v=-VEf8j6aGMk • https://www.martinfowler.com/bliki/StranglerApplication.html Celebrate your successes • https://medium.com/@Songkick/gamify-your-product-team-to-power- level-9000-261e9fceaa22 Hoarders metaphor / Liveable code • https://twitter.com/sarahmei/status/783115752794492928 • https://brightonruby.com/2017/livable-code-sarah-mei/ • https://twitter.com/kentbeck/status/856537528886673408 Product discovery and product delivery • http://jpattonassociates.com/dual-track-development/ • https://martinfowler.com/bliki/DesignStaminaHypothesis.html • https://www.facebook.com/notes/kent-beck/teams-in-3x/1244519748914220/ References
97. References Make the cost visible • http://codemanship.co.uk/parlezuml/blog/?postid=1433 • http://blogs.msdn.com/b/elee/archive/2009/03/11/source-code-is-a-liability-not-an- asset.aspx Make it part of your day-to-day • https://martinfowler.com/bliki/OpportunisticRefactoring.html • http://ronjeffries.com/xprog/articles/refactoring-not-on-the-backlog/ • http://firstround.com/review/forget-technical-debt-heres-how-to-build-technical- wealth/ • https://www.infoq.com/presentations/microservices-replaceability-consistency • https://www.sandimetz.com/blog/2017/6/1/the-half-life-of-code • https://www.infoq.com/presentations/remove-unneeded-code Playlist :) • https://open.spotify.com/user/saleandro/playlist/6i3RVHtys4djlYlLLGZc26