Growing Object-Oriented System

Transcript

1. Growing Object-Oriented System Principles, Guidelines, and Methods Kent Wang Dec 6, 2012
2. Agenda • Introduction • Understand The Problem • Broad-Brush Design • Implementation • Recommended Readings
3. Introduction
4. Why This Talk
6. Software Developing Is a Learning Process
7. Feedback is Critical Understand the Problem (Analysis) Broad-Brush Design (Architecture) Test Driven Development (Implementation) Deployable System
8. Understand the Problem
9. Understand The Problem • User Story • Use Case • Conceptual Model • Color Modeling
10. User Story Users could pay for their orders from various platform via tenpay
11. Use Case User Pay
12. Use Case Is Valuable But Not The End
13. Digging A Conceptual Model
14. Dig Conceptual Model
15. Dig Conceptual Model Payment
16. Dig Conceptual Model Payment Partner Trade
17. Dig Conceptual Model Payment Partner Partner Trade
18. Dig Conceptual Model Payment Partner User Partner Trade
19. Dig Conceptual Model Payment Partner User Buyer Seller Partner Trade
20. Dig Conceptual Model Payment Partner User Payment Type Buyer Seller Partner Trade
21. Color Modeling
22. Color Modeling Moment- Interval
23. Color Modeling Moment- Interval Party / Place /Thing
24. Color Modeling Moment- Interval Role Party / Place /Thing
25. Color Modeling Moment- Interval Role Description Party / Place /Thing
26. User Story Changed Users could pay for their orders from various platform via tenpay or alipay
27. Simple Solution Payment Partner User Payment Type Buyer Seller Partner Trade
28. Simple Solution Payment Partner User Payment Type Buyer Seller Partner Trade
29. The Missing Concept Payment Partner User Payment Type Buyer Seller Partner Trade
30. The Missing Concept Payment Partner User Payment Type Buyer Seller Partner Trade Provider Payment
31. The Missing Concept Payment Partner User Payment Type Buyer Seller Partner Trade Provider Payment Payment Provider
32. Models Are Not Right Or Wrong They Are More Or Less Useful
33. One Team, One Language
34. Bounded Context Payment Partner Payment Type Provider Payment Payment Provider
35. Context Map Provider Payment Transaction unipay tenpay
36. Context Map Provider Payment Transaction unipay tenpay Transaction Map
37. Get Help If Required
38. Broad-Brush Design
39. Broad-Brush Design • Tackling Complexity • Architectural Level • Application Level • Domain Model Level
40. Tackling Complexity
41. Separation of Concerns
42. Layered Architecture Application Presentation Data Source
43. Layered Architecture Application Presentation Data Source Domain
44. High Level of Abstraction
45. High Level of Abstraction
46. Architectural Level
47. Infrastructure • Distributed or Not • Synchronous or Asynchronous • Data Source
48. Architectural Style Transaction Script Table Module Domain Model Complexity Tool-Chain
49. Location of Domain Logic DAO AO vs.
50. Location of Domain Logic DAO AO Domain vs.
51. Location of Domain Logic DAO AO Domain vs.
52. Location of Domain Logic DAO AO Domain vs.
53. Concurrent Control • Transaction is not Silver Bullet • Optimistic or Pessimistic • Offline or Not
54. Application Level
55. Walking Through Scenarios
56. Walking Through Scenarios User Submit Payment Save Payment Get Payment Parameter Submit To Provider
57. Walking Through Scenarios User Submit Payment Save Payment Get Payment Parameter Submit To Provider Presentation Layer Application Layer
58. Intension-Revealing Interface CUnipayAO GetPaymentParameter CUnipayAO ProcessTrade vs.
59. Do One Thing CUnipayAO GetPaymentParameter
60. Do One Thing CUnipayAO GetPaymentParameter Save or update Payments Assemble Payment Parameters
61. Command Query Separation System Command Query State A
62. Command Query Separation System Command Query State B
63. Command Query Separation System Command Query State B
64. Command Query Separation CUnipayAO GetPaymentParameter SetupPayment Save or update Payments Assemble Payment Parameters
65. Module Payment Payment Provider Partner Notification History Security Settlement
66. Domain Model Level
67. Simplify Associations Payment Partner User Payment Type Buyer Seller Partner Trade Provider Payment Payment Provider
68. Simplify Associations Payment Partner Payment Type Partner Trade Provider Payment Payment Provider
69. Simplify Associations Payment Partner Payment Type Provider Payment Payment Provider 1..*
70. Simplify Associations Payment Partner Payment Type Provider Payment Payment Provider 1 current
71. Design Is Not Just A Technical Issue
72. Integrity Problem ChargePlan ChargePlan LineItem ChargePlan LineItem amount = 50 amount = 50 amount = 100
73. Integrity Problem ChargePlan ChargePlan LineItem ChargePlan LineItem amount = 50 amount = 50 amount = 100 ChargePlan LineItem amount = 50
74. Aggregate ChargePlan ChargePlan LineItem ChargePlan LineItem amount = 50 amount = 50 amount = 100
75. Aggregate ChargePlan ChargePlan LineItem ChargePlan LineItem amount = 50 amount = 50 amount = 100 ChargePlan LineItem amount = 50
76. Domain Model Pollution ao_unipay_settle Payment Relay Service ao_unipay Transaction
77. Anti-Corruption Layer ao_unipay_settle nao_unipay_tenpay Tenpay Service Payment Relay Service ao_unipay Transaction
78. Design To Test Tenpay Service Facade
79. Design To Test Tenpay Service Facade Mock Tenpay Relay Client Tenpay Service Facade Test
80. Design To Test Tenpay Service Facade Mock Tenpay Relay Client Tenpay Service Facade Test 1. RegisterChargePlan(plan) 3. Execute(request, response) 4. Checking Request 5. Return Response 6. Return Response 7. Parse Response 2. Assemble Request 8. Return Result 9. Checking Result
81. Implementation
82. Implementation • Design Tools • Make A New Type • Consistent Abstraction Level • Open Close Principle • Extract Hidden Concept
83. Costly Tools Don’t Produce Better Designs
84. UML Without CASE
85. CRC Card CTenpayProviderType Make Tenpay Trade No Make Tenpay Settle No Get Request Builder CTenpayTradeNo CTenpayProvider CTenpayRequest Builder
86. CRC Card CTenpayProviderType Make Tenpay Trade No Make Tenpay Settle No Get Request Builder CTenpayTradeNo CTenpayProvider CTenpayRequest Builder Class Responsibility Collaborator
87. Duplicated Code // inside NotifyPayment function // inside GetPayment fuction if (sProviderTradeNo.length() != 28) { return ERR_APP_PARAM_INVALID; } uint64_t ddwProviderPartnerNo = lexical_cast<uint64_t>(sProviderTradeNo.substr(0, 10)) uint64_t ddwSerialNo = lexical_cast<uint64_t>(sProviderTradeNo.substr(18)); dwRet = GetPaymentByProviderTradeNo( ddwProviderPartnerNo, ddwSerialNo);
88. Make A New Type CTenpayTradeNo Make Tenpay Trade No Parse Tenpay Trade No Verify Tenpay Trade No CTenpayProvider Get Date From Trade No Get Serial No From Trade No
89. Use The New Type // inside NotifyPayment function // inside GetPayment fuction CTenpayTradeNo oTradeNo; if (!CProviderTradeNo::TryParse(sProviderTradeNo, oTradeNo) { return ERR_APP_PARAM_INVALID; } dwRet = GetPaymentByProviderTradeNo( oTradeNo.GetProviderPartnerNo(), oTradeNo.GetProviderTradeSerialNo());
90. Too Much Detail // inside SetupPayment function if (dwRet == ERR_PAYMENT_NOT_FOUND) { CPayment oPayment; oPayment.SetPaymentId(NextPaymentId()); oPayment.SetAmount(rTrade.GetAmount()); oPayment.SetBuyerUid(rTrade.GetBuyerUid()); oPayment.SetSellerUid(rTrade.GetSellerUid()); // ... 50 lines more oPayment.SetLastUpdateTime(CTime::Now()); dwRet = m_pDao->SavePayment(oPayment); if (dwRet != 0) { // ... 10 lines of error handling } return dwRet; }
91. Too Much Detail // inside SetupPayment function if (dwRet == ERR_PAYMENT_NOT_FOUND) { CPayment oPayment; oPayment.SetPaymentId(NextPaymentId()); oPayment.SetAmount(rTrade.GetAmount()); oPayment.SetBuyerUid(rTrade.GetBuyerUid()); oPayment.SetSellerUid(rTrade.GetSellerUid()); // ... 50 lines more oPayment.SetLastUpdateTime(CTime::Now()); dwRet = m_pDao->SavePayment(oPayment); if (dwRet != 0) { // ... 10 lines of error handling } return dwRet; }
92. Code Closer To Problem // inside SetupPayment function if (IsPaymentNotExist(dwRet)) { return CreatePayment(); } else { return MakeSurePriceHasNotChanged(); }
93. Code Closer To Problem // inside SetupPayment function if (IsPaymentNotExist(dwRet)) { return CreatePayment(); } else { return MakeSurePriceHasNotChanged(); }
94. Keep Consistent Abstraction Level
95. Feature Envy // inside GetPaymentParameter function ... if (rProvider.GetType() == TENPAY) { BuildBasicParameter(rPayment); if (rSpec.GetPaymentMethod() == STANDARD) { BuildParameterOfTenpayStandardPayment(rPayment); } else if (rSpec.GetPaymentMethod() == BANK) { BuildParameterOfTenpayBankPayment(rPayment); } } ...
96. Feature Envy // inside GetPaymentParameter function ... if (rProvider.GetType() == TENPAY) { BuildBasicParameter(rPayment); if (rSpec.GetPaymentMethod() == STANDARD) { BuildParameterOfTenpayStandardPayment(rPayment); } else if (rSpec.GetPaymentMethod() == BANK) { BuildParameterOfTenpayBankPayment(rPayment); } } ...
97. Power Of Values IPaymentRequestBuilder Build Payment Request GetPaymentUrl CopyPaymentParameters CProviderType CProvider CTenpayStandardPayment RequestBuilder Build Payment Request GetPaymentUrl CopyPaymentParameters CTenpayProviderType CTenpayBankPayment RequestBuilder Build Payment Request GetPaymentUrl CopyPaymentParameters CTenpayProviderType
98. The Clean Way // inside GetPaymentParameter function ... IPaymentRequestBuilder* pBuilder = rSpec.GetPaymentMethod(). NewPaymentRequestBuilder(rProvider); pBuilder->Build(rPayment); ...
99. Open for Extension Close for Modification
100. Extract Hidden Concept // inside NotifyPayment function ... if (rPayment.GetCurrentProviderPaymentId() == rProviderPayment.GetProviderPaymentId() && rPayment.IsWaitPay()) { rPayment.Accept(rProviderPayment); } ...
101. Extract Hidden Concept // inside NotifyPayment function ... if (rPayment.GetCurrentProviderPaymentId() == rProviderPayment.GetProviderPaymentId() && rPayment.IsWaitPay()) { rPayment.Accept(rProviderPayment); } ...
102. Extract Hidden Concept Payment ProviderPayment IPaymentAcceptingPolicy *
103. Extract Hidden Concept // inside NotifyPayment function IPaymentAcceptingPolicy* paymentAcceptingPolicy; ... if (paymentAcceptingPolicy->IsAllowedToAccept( rPayment, rProviderPayment)) { rPayment.Accept(rProviderPayment); } ...
104. Extract Hidden Concept // inside NotifyPayment function IPaymentAcceptingPolicy* paymentAcceptingPolicy; ... if (paymentAcceptingPolicy->IsAllowedToAccept( rPayment, rProviderPayment)) { rPayment.Accept(rProviderPayment); } ...
105. Making Implicit Concept Explicit
106. Recommended Readings
109. Q & A
110. Thanks for your time