Domain-Driven Transformation

Transcript

1. Starring Directed By Special Appearance Presented by Photo: Hackercatxxy/Wikipedia
3. THE NAME OF THIS SPEAKER IS HENNING SCHWENTNER LIVE 45 MIN TALK
4. !"# Kolleg:in gesucht (Deutschlandweit)
6. @hschwentner
7. @hschwentner Alphorn Auto Leasing Inc.
8. @hschwentner
9. @hschwentner
10. Monolease A
11. salesperson [person] Monolease [software system] Central car leasing tool customer [external person] risk manager [person] closes leasing contracts with creates and calculates contracts in assesses risk of contracts in Alphorn Auto Leasing Inc. [enterprise] Context
12. @hschwentner Alphorn’s boss: “Modernize it!”
13. @hschwentner Diagnosis: From Which Diseases Does Our Patient suffer?
14. @hschwentner Different diseases require different treatment
15. @hschwentner big ball of mud anemic domain model bad team organization Typical Diseases of Legacy Systems
16. @hschwentner big ball of mud anemic domain model bad team organization Cures strategic transformation tactical transformation socio-technical transformation
17. @hschwentner Domain-Driven Refactorings • Strategic • Socio-Technical • Tactical (Against Model Anemia) • Tactical (Against Big Ball of Mud) Catalog: https://hschwentner.io/domain-driven-refactorings
18. @hschwentner Strategic
19. @hschwentner Strategic Transformation 1. Step: Domain re-discovery 2. Step: Modeling the to-be 3. Step: Aligning as-is with to-be 4. Step: Do the move RISK MANAGE- MENT SALES
20. @hschwentner Controlling Complexity as Key to Modernization
21. “The most fundamental problem in software development is complexity. ” Bjarne Stroustrup
22. Controlling complexity is the essence of computer programming Brian Kernighan
23. “There is only one basic way of dealing with complexity: divide and conquer.” Bjarne Stroustrup
26. @hschwentner Too big to be understood as a whole
27. Photo: Henning Schwentner
29. @hschwentner How to Modernize IT Infratructure?
30. @hschwentner Replace or Transform
31. old old old old new new new new “just flip the lever” 1 2 3 4 5 a.k.a. big bang replacement
32. old old old new new new new 2 3 4 5 old 1
33. Strangler Fig Application Photo: Henning Schwentner
34. Strangler Fig Application
35. Lesson: is better than Strangler Fig Application Big Bang Replacement
36. => bounded contexts monolith buy to carve out build new
37. @hschwentner Step 1: Domain Re-Discovery
38. @hschwentner To split the monolith we first have to put it aside
39. @hschwentner Mindset Switch
40. thinking about business => thinking about technology to
41. Collaborative Modeling
42. Collaborative Modeling
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://hschwentner.io Read on in:
45. @hschwentner Step 2: Determining the To-Be Architecture
46. @hschwentner Drawing Boundaries
47. @hschwentner Scope: coarse-grained to-be (optimized) pure
48. Which activities belong together (from an actor’s perspective)?
49. 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 sales risk assessment
50. Sales Risk assessment
51. @hschwentner Step 3: Aligning As-Is with To-Be
52. salesperson [person] Monolease [software system] Central car leasing tool customer [external person] risk manager [person] closes leasing contracts with creates and calculates contracts in assesses risk of contracts in Alphorn Auto Leasing Inc. [enterprise] Context again
53. salesperson [person] backend [container: EJB 2] risk manager [person] creates and calculates contracts in assesses risk of contracts in Monolease [software system] frontend [container: servlets, JSPs] database [container: IBM DB2] Containers
54. Calculator [component] frontend [container] LeasingServlet [component: servlet] CONTRACTS [database table] PartnerServlet [component: servlet] ContractService [component] PartnerService [component] backend [container] database [container] Contract [component] Partner [component] PARTNERS [database table] Components
55. big ball of mud => no vertical structuring
56. Calculator [component] frontend [container] LeasingServlet [component: servlet] CONTRACTS [database table] PartnerServlet [component: servlet] ContractService [component] PartnerService [component] backend [container] database [container] Contract [component] Partner [component] PARTNERS [database table] Components
57. Calculator [component] ContractService [component] PartnerService [component] backend [container] Contract [component] Partner [component] Component Backend
58. Calculator [component] ContractService [component] PartnerService [component] Contract [component] Partner [component] Component Bounded Contexts Sales Risk Assessment
59. Calculator [component] ContractService [component] PartnerService [component] Contract [component] Partner [component] Sales Risk Assessment Contract [component] Partner [component] Duplication?
60. ContractService [component] Contract [component] Component Backend Sales Risk assessment
61. ContractService signContract() voteContract() Code Contract getContractNumber() setSignatureDate() setCreditRa7ng() setVo7ngResult() Sales Risk Assessment
62. ContractService signContract() voteContract() Code Contract getContractNumber() setSignatureDate() setCreditRating() setVotingResult() Sales Risk Assessment ContractService signContract() voteContract() Contract getContractNumber() setSignatureDate() setCreditRating() setVotingResult()
63. ContractService signContract() Code Contract getContractNumber() setSignatureDate() Sales Risk Assessment ContractService voteContract() Contract getContractNumber() setCreditRa7ng() setVo7ngResult()
64. ContractService signContract() Code Contract getContractNumber() setSignatureDate() Sales Risk Assessment ContractService voteContract() Contract getContractNumber() setCreditRating() setVotingResult()
65. @hschwentner 1.2 Extract Specialized “Contract Service” 1.1 Extract Specialized “Contract” 1 Extract Context “Sales” Transformation Backlog 2 Extract Context “Risk assessment” 2.1 Extract Specialized “Contract Service” 2.1 Extract Specialized “Contract”
66. @hschwentner Insertion: Domain-Driven Refactorings
67. @hschwentner Domain-Driven Refactorings • Strategic • Socio-Technical • Tactical (Against Model Anemia) • Tactical (Against Big Ball of Mud)
68. @hschwentner Strategic DDRs • Extract Bounded Context • Implement Bounded Context from Scratch
69. @hschwentner Tactical DDRs (to Support Strategic) • Extract Specialized Entity • Extract Specialized Anemic Entity • Extract Specialized Service • Extract Specialized Data Model
70. @hschwentner Extract Bounded Context Mechanics • Analyze the domain to find out which bounded contexts should be there. • Identify a carve-out candidate context • Create an empty package/namespace/module for the to-be carved out context besides the big ball of mud. • Apply the Tactical (to Support Strategic) refactorings that are right for your situation.
71. @hschwentner Extract Specialized Anemic Entity Mechanics • Create empty new class in carved-out context • Add instance field of type new class to the old class • Copy to-be-moved fields from old to new class => Move Field • Copy first to-be-moved method to new class => Move Method • Replace method body in old class with a forward to method in new class • Step by step replace calls to the method in the old class with calls to the method in the new class • Delete the implementation in the old class • Delete now unused fields in old class • Repeat with other to-be-moved methods • Remove instance field of type new class in the old class
72. Read on at: https://hschwentner.io/domain-driven-refactorings
73. @hschwentner Step 4: Do the Move
74. @hschwentner Transformation Backlog Planning Transformation Tactical Refactoring 1.2 Strategic Refactoring 1 User Story A Product Backlog User Story E User Story B User Story C User Story D Tactical Refactoring 1.3 Tactical Refactoring 1.4 Tactical Refactoring 2.1 Strategic Refactoring 2 Sprint Backlog
75. @hschwentner Transformation Backlog Planning Transformation Tactical Refactoring 1.2 Strategic Refactoring 1 User Story A Product Backlog User Story E User Story B User Story C User Story D Tactical Refactoring 1.3 Tactical Refactoring 1.4 Tactical Refactoring 2.1 Strategic Refactoring 2 Sprint Backlog
76. @hschwentner Transformation Backlog Planning Transformation Strategic Refactoring 1 Product Backlog User Story E User Story C User Story D Tactical Refactoring 1.4 Tactical Refactoring 2.1 Strategic Refactoring 2 Sprint Backlog
77. @hschwentner Transformation Backlog Planning Transformation Strategic Refactoring 1 Product Backlog User Story E User Story C User Story D Tactical Refactoring 1.4 Tactical Refactoring 2.1 Strategic Refactoring 2 Sprint Backlog User Story F User Story G
78. @hschwentner Transformation Backlog Planning Transformation Product Backlog User Story E Tactical Refactoring 2.1 Strategic Refactoring 2 Sprint Backlog User Story F User Story G
79. @hschwentner Transformation Backlog Planning Transformation Product Backlog User Story E Tactical Refactoring 2.1 Strategic Refactoring 2 Sprint Backlog User Story G User Story H User Story F User Story I
80. ContractService signContract() voteContract() Code Contract getContractNumber() setSignatureDate() setCreditRating() setVotingResult() Risk Assessment ContractService Contract Monolease voteContract() getContractNumber() setCreditRating() setVotingResult()
81. ContractService signContract() Code Contract getContractNumber() setSignatureDate() Risk Assessment ContractService Contract Monolease voteContract() getContractNumber() setCreditRating() setVotingResult()
82. @hschwentner Tactical
83. Code Risk Assessment ContractService voteContract() Contract getContractNumber() setCreditRating() setVotingResult() anemic
85. @hschwentner Outlook
86. @hschwentner What Else? Socio-technical transformation Technical transformation Tactical transformation Anti-Anemia refactorings
87. @hschwentner Domain Categories Pipeline Domain Blackboard Domain Dialog Domain • Logistics • Insurances and banks • administration • healthcare • event management • control center • Software development • Communication software • Negotiations in various domains or Domain Patterns?
88. @hschwentner Conclusion
90. https://hschwentner.io Read on in: https://hschwentner.io/domain-driven-refactorings
91. Lesson: is possible Monolith transformation (and hard) =>
92. @hschwentner Mistake: Going on the journey alone Better:
93. Photo: Henning Schwentner
94. ! ❤
95. @hschwentner
96. Bibliography Foote, Brian and Joseph Yoder. “Big Ball of Mud.” PLoP ’97, Monticello, IL, September 1997. 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. Lilienthal, Carola and Henning Schwentner. Domain-Driven Transformation. Heidelberg: dpunkt, 2023. Kernighan, Brian W. Software Tools in Pascal. Addison-Wesley, 1981.
98. Henning Schwentner ⌂ https://hschwentner.io @hschwentner hs@wps.de
99. (Software) Seam: A place where you can alter behavior in your program without editing in that place Every Seam has an enabling point, a place where you can make the decision to use one behavior or the other
101. Typical Seam: An interface that can have different implementations