From Legacy to Cloud

A journey from monolithic, on-premise, customized, legacy software to cloud-native, multi-tenant, domain-driven SAAS.

Transcript

1. Starring Directed By Special Appearance Presented by With
6. 👨💻👨🏫👨💼
7. @hschwentner
8. Alphorn Auto Leasing Inc.
10. Springfield Duckburg Metropolis
11. Monolease A
12. Springfield Duckburg Metropolis 1.0 1.1 1.0a
13. Springfield Duckburg Metropolis Twin Peaks 1.1 1.0 1.1 1.0a
14. => cloud on-premise to
15. @hschwentner Mistake: Move to the cloud because some random dude at a conference said so Better: Move to the cloud because that solves an actual problem
16. Springfield Duckburg Metropolis Leas- N-dary
17. Springfield Duckburg Twin Peaks Metropolis Leas- N-dary
18. Springfield Duckburg Twin Peaks Metropolis Leas- N-dary 2.0
19. @hschwentner Mistake: Continue working like you always did Better: Change your mindset
20. product project to =>
21. => agile waterfall to
22. Individuals and interactions over processes and tools Customer collaboration over contract negotiation Working software over comprehensive documentation Responding to change over following a plan Agile Manifesto
23. => micro- services monolith to
24. @hschwentner Mistake: Transform the whole system at once Better: Move in baby steps
25. old old old old new new new new “just flip the lever” 1 2 3 4 5 a.k.a. big bang replacement
26. old old old new new new new 2 3 4 5 old 1
27. Strangler Fig Application
28. Strangler Fig Application
29. Lesson: is better than Strangler Fig Application Big Bang Replacement
30. => micro- services monolith buy to carve out build new
31. Read on in:
32. big ball of mud => strategic design to
33. @hschwentner Mistake: Cutting the system by technical reasons Better: Cutting the system into bounded contexts
34. => tactical design anemic domain model to value object entity repository impleme- ntation
35. behavior data to 1001010011 1110010110 0010011101 calculatePrice() assessRisk() signContract()
36. Eric Evans Read on in:
37. Individuals and interactions over processes and tools Customer collaboration over contract negotiation Working software over comprehensive documentation Responding to change over following a plan Agile Manifesto
38. doctor waiter to => What are your orders? What is your problem?
39. @hschwentner Mistake: Thinking that it’s about software Better: Realizing that it’s about business
40. business enabling => technology- centered to
41. What's the most impactful thing we can do next?
42. Software != End in itself
43. customer tells wish for 1 salesperson signs to gives for contract 3 risk manager contract passes on to 4 contract votes checks calculates 5 6 7 calculates to 8 2 car credit rating installment car resale value contract
44. https://domainstorytelling.org Read on in:
45. @hschwentner Lesson: 1. First understand the business 2. Only then build software
46. @hschwentner Lesson: 1. First learn about the problem 2. Only then look for a solution
47. @hschwentner What is Software? technical system socio- +
48. “Organizations which design systems are constrained to produce designs which are copies of the communication structures of these organizations.” Melvin Conway
49. @hschwentner Mistake: Ignoring team organization Better: Respect Conway’s law
50. => micro- services monolith to cross- functional teams
51. Alignment technical business-wise organizational technical business-wise organizational
52. Read on in:
53. Individuals and interactions over processes and tools Customer collaboration over contract negotiation Working software over comprehensive documentation Responding to change over following a plan Agile Manifesto
54. user dev
55. @hschwentner Mistake: Misunderstand your users Better: Build a common language
56. @hschwentner 🧑💼 👨💻 👨💼 have to understand The single most important fact in software development: Tech people business people. 👩💼 👩💻
57. => direct commu- nication telephone game to user dev user dev
58. finance dev user sales PO HR management marketing scrum master UX
59. Individuals and interactions over processes and tools Customer collaboration over contract negotiation Working software over comprehensive documentation Responding to change over following a plan Agile Manifesto
60. It’s a full team sport Photo: Bart Derksen/Wikipedia
61. @hschwentner Mistake: Thinking “We’re never gonna make it”
62. We can do it, too!
63. @hschwentner Mistake: Going on the journey alone Better:
66. Bibliography Beck, Kent et al. Manifesto for Agile Software Development. 2001. Conway, Melvin E. “How Do Committees Invent?” Datamation 14, no. 5 (April 1968): 28–31. Evans, Eric. Domain-Driven Design: Tackling Complexity in the Heart of Software. Boston: Addison-Wesley, 2004. Feathers, Michael C. Working Effectively with Legacy Code. Upper Saddle River, NJ: Prentice Hall, 2004. Foote, Brian and Joseph Yoder. “Big Ball of Mud.” PLoP ’97, Monticello, IL, September 1997. Fowler, Martin. Refactoring: Improving the Design of Existing Code. 2nd ed. Boston: Addison-Wesley, 2019. Fowler, Martin. “Strangler Fig Application.” Bliki, June 29, 2004. Hofer, Stefan and Henning Schwentner. Domain Storytelling: a Collaborative, Visual, and Agile Way to Develop Domain-Driven Software. Boston: Addison-Wesley, 2022. Kaur, Ravneet. “Agile Teams—Are They Waiters or Doctors?” LinkedIn. April 1, 2019. Kernighan, Brian W. Software Tools in Pascal. Addison-Wesley, 1981. Newman, Sam. Monolith to Microservices: Evolutionary Patterns to Transform Your Monolith. Sebastopol, CA: O’Reilly, 2021. Skelton, Matthew and Manuel Pais. Team Topologies: Organizing Business and Technology Teams for Fast Flow. Portland, OR: IT Revolution, 2019. Weinberg, Gerald M. The Secrets of Consulting. New York: Dorset House, 1985.
68. Henning Schwentner  https://hschwentner.io  @hschwentner ✉ hs@wps.de