Growing Object-Oriented System

Slide 1

Slide 1 text

Growing Object-Oriented System Principles, Guidelines, and Methods Kent Wang Dec 6, 2012

Slide 2

Slide 2 text

Agenda • Introduction • Understand The Problem • Broad-Brush Design • Implementation • Recommended Readings

Slide 3

Slide 3 text

Introduction

Slide 4

Slide 4 text

Why This Talk

Slide 5

Slide 5 text

No content

Slide 6

Slide 6 text

Software Developing Is a Learning Process

Slide 7

Slide 7 text

Feedback is Critical Understand the Problem (Analysis) Broad-Brush Design (Architecture) Test Driven Development (Implementation) Deployable System

Slide 8

Slide 8 text

Understand the Problem

Slide 9

Slide 9 text

Understand The Problem • User Story • Use Case • Conceptual Model • Color Modeling

Slide 10

Slide 10 text

User Story Users could pay for their orders from various platform via tenpay

Slide 11

Slide 11 text

Use Case User Pay

Slide 12

Slide 12 text

Use Case Is Valuable But Not The End

Slide 13

Slide 13 text

Digging A Conceptual Model

Slide 14

Slide 14 text

Dig Conceptual Model

Slide 15

Slide 15 text

Dig Conceptual Model Payment

Slide 16

Slide 16 text

Dig Conceptual Model Payment Partner Trade

Slide 17

Slide 17 text

Dig Conceptual Model Payment Partner Partner Trade

Slide 18

Slide 18 text

Dig Conceptual Model Payment Partner User Partner Trade

Slide 19

Slide 19 text

Dig Conceptual Model Payment Partner User Buyer Seller Partner Trade

Slide 20

Slide 20 text

Dig Conceptual Model Payment Partner User Payment Type Buyer Seller Partner Trade

Slide 21

Slide 21 text

Color Modeling

Slide 22

Slide 22 text

Color Modeling Moment- Interval

Slide 23

Slide 23 text

Color Modeling Moment- Interval Party / Place /Thing

Slide 24

Slide 24 text

Color Modeling Moment- Interval Role Party / Place /Thing

Slide 25

Slide 25 text

Color Modeling Moment- Interval Role Description Party / Place /Thing

Slide 26

Slide 26 text

User Story Changed Users could pay for their orders from various platform via tenpay or alipay

Slide 27

Slide 27 text

Simple Solution Payment Partner User Payment Type Buyer Seller Partner Trade

Slide 28

Slide 28 text

Simple Solution Payment Partner User Payment Type Buyer Seller Partner Trade

Slide 29

Slide 29 text

The Missing Concept Payment Partner User Payment Type Buyer Seller Partner Trade

Slide 30

Slide 30 text

The Missing Concept Payment Partner User Payment Type Buyer Seller Partner Trade Provider Payment

Slide 31

Slide 31 text

The Missing Concept Payment Partner User Payment Type Buyer Seller Partner Trade Provider Payment Payment Provider

Slide 32

Slide 32 text

Models Are Not Right Or Wrong They Are More Or Less Useful

Slide 33

Slide 33 text

One Team, One Language

Slide 34

Slide 34 text

Bounded Context Payment Partner Payment Type Provider Payment Payment Provider

Slide 35

Slide 35 text

Context Map Provider Payment Transaction unipay tenpay

Slide 36

Slide 36 text

Context Map Provider Payment Transaction unipay tenpay Transaction Map

Slide 37

Slide 37 text

Get Help If Required

Slide 38

Slide 38 text

Broad-Brush Design

Slide 39

Slide 39 text

Broad-Brush Design • Tackling Complexity • Architectural Level • Application Level • Domain Model Level

Slide 40

Slide 40 text

Tackling Complexity

Slide 41

Slide 41 text

Separation of Concerns

Slide 42

Slide 42 text

Layered Architecture Application Presentation Data Source

Slide 43

Slide 43 text

Layered Architecture Application Presentation Data Source Domain

Slide 44

Slide 44 text

High Level of Abstraction

Slide 45

Slide 45 text

High Level of Abstraction

Slide 46

Slide 46 text

Architectural Level

Slide 47

Slide 47 text

Infrastructure • Distributed or Not • Synchronous or Asynchronous • Data Source

Slide 48

Slide 48 text

Architectural Style Transaction Script Table Module Domain Model Complexity Tool-Chain

Slide 49

Slide 49 text

Location of Domain Logic DAO AO vs.

Slide 50

Slide 50 text

Location of Domain Logic DAO AO Domain vs.

Slide 51

Slide 51 text

Location of Domain Logic DAO AO Domain vs.

Slide 52

Slide 52 text

Location of Domain Logic DAO AO Domain vs.

Slide 53

Slide 53 text

Concurrent Control • Transaction is not Silver Bullet • Optimistic or Pessimistic • Offline or Not

Slide 54

Slide 54 text

Application Level

Slide 55

Slide 55 text

Walking Through Scenarios

Slide 56

Slide 56 text

Walking Through Scenarios User Submit Payment Save Payment Get Payment Parameter Submit To Provider

Slide 57

Slide 57 text

Walking Through Scenarios User Submit Payment Save Payment Get Payment Parameter Submit To Provider Presentation Layer Application Layer

Slide 58

Slide 58 text

Intension-Revealing Interface CUnipayAO GetPaymentParameter CUnipayAO ProcessTrade vs.

Slide 59

Slide 59 text

Do One Thing CUnipayAO GetPaymentParameter

Slide 60

Slide 60 text

Do One Thing CUnipayAO GetPaymentParameter Save or update Payments Assemble Payment Parameters

Slide 61

Slide 61 text

Command Query Separation System Command Query State A

Slide 62

Slide 62 text

Command Query Separation System Command Query State B

Slide 63

Slide 63 text

Command Query Separation System Command Query State B

Slide 64

Slide 64 text

Command Query Separation CUnipayAO GetPaymentParameter SetupPayment Save or update Payments Assemble Payment Parameters

Slide 65

Slide 65 text

Module Payment Payment Provider Partner Notiﬁcation History Security Settlement

Slide 66

Slide 66 text

Domain Model Level

Slide 67

Slide 67 text

Simplify Associations Payment Partner User Payment Type Buyer Seller Partner Trade Provider Payment Payment Provider

Slide 68

Slide 68 text

Simplify Associations Payment Partner Payment Type Partner Trade Provider Payment Payment Provider

Slide 69

Slide 69 text

Simplify Associations Payment Partner Payment Type Provider Payment Payment Provider 1..*

Slide 70

Slide 70 text

Simplify Associations Payment Partner Payment Type Provider Payment Payment Provider 1 current

Slide 71

Slide 71 text

Design Is Not Just A Technical Issue

Slide 72

Slide 72 text

Integrity Problem ChargePlan ChargePlan LineItem ChargePlan LineItem amount = 50 amount = 50 amount = 100

Slide 73

Slide 73 text

Integrity Problem ChargePlan ChargePlan LineItem ChargePlan LineItem amount = 50 amount = 50 amount = 100 ChargePlan LineItem amount = 50

Slide 74

Slide 74 text

Aggregate ChargePlan ChargePlan LineItem ChargePlan LineItem amount = 50 amount = 50 amount = 100

Slide 75

Slide 75 text

Aggregate ChargePlan ChargePlan LineItem ChargePlan LineItem amount = 50 amount = 50 amount = 100 ChargePlan LineItem amount = 50

Slide 76

Slide 76 text

Domain Model Pollution ao_unipay_settle Payment Relay Service ao_unipay Transaction

Slide 77

Slide 77 text

Anti-Corruption Layer ao_unipay_settle nao_unipay_tenpay Tenpay Service Payment Relay Service ao_unipay Transaction

Slide 78

Slide 78 text

Design To Test Tenpay Service Facade

Slide 79

Slide 79 text

Design To Test Tenpay Service Facade Mock Tenpay Relay Client Tenpay Service Facade Test

Slide 80

Slide 80 text

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

Slide 81

Slide 81 text

Implementation

Slide 82

Slide 82 text

Implementation • Design Tools • Make A New Type • Consistent Abstraction Level • Open Close Principle • Extract Hidden Concept

Slide 83

Slide 83 text

Costly Tools Don’t Produce Better Designs

Slide 84

Slide 84 text

UML Without CASE

Slide 85

Slide 85 text

CRC Card CTenpayProviderType Make Tenpay Trade No Make Tenpay Settle No Get Request Builder CTenpayTradeNo CTenpayProvider CTenpayRequest Builder

Slide 86

Slide 86 text

CRC Card CTenpayProviderType Make Tenpay Trade No Make Tenpay Settle No Get Request Builder CTenpayTradeNo CTenpayProvider CTenpayRequest Builder Class Responsibility Collaborator

Slide 87

Slide 87 text

Duplicated Code // inside NotifyPayment function // inside GetPayment fuction if (sProviderTradeNo.length() != 28) { return ERR_APP_PARAM_INVALID; } uint64_t ddwProviderPartnerNo = lexical_cast(sProviderTradeNo.substr(0, 10)) uint64_t ddwSerialNo = lexical_cast(sProviderTradeNo.substr(18)); dwRet = GetPaymentByProviderTradeNo( ddwProviderPartnerNo, ddwSerialNo);

Slide 88

Slide 88 text

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

Slide 89

Slide 89 text

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());

Slide 90

Slide 90 text

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; }

Slide 91

Slide 91 text

Slide 92

Slide 92 text

Code Closer To Problem // inside SetupPayment function if (IsPaymentNotExist(dwRet)) { return CreatePayment(); } else { return MakeSurePriceHasNotChanged(); }

Slide 93

Slide 93 text

Code Closer To Problem // inside SetupPayment function if (IsPaymentNotExist(dwRet)) { return CreatePayment(); } else { return MakeSurePriceHasNotChanged(); }

Slide 94

Slide 94 text

Keep Consistent Abstraction Level

Slide 95

Slide 95 text

Feature Envy // inside GetPaymentParameter function ... if (rProvider.GetType() == TENPAY) { BuildBasicParameter(rPayment); if (rSpec.GetPaymentMethod() == STANDARD) { BuildParameterOfTenpayStandardPayment(rPayment); } else if (rSpec.GetPaymentMethod() == BANK) { BuildParameterOfTenpayBankPayment(rPayment); } } ...

Slide 96

Slide 96 text

Slide 97

Slide 97 text

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

Slide 98

Slide 98 text

The Clean Way // inside GetPaymentParameter function ... IPaymentRequestBuilder* pBuilder = rSpec.GetPaymentMethod(). NewPaymentRequestBuilder(rProvider); pBuilder->Build(rPayment); ...

Slide 99

Slide 99 text

Open for Extension Close for Modification

Slide 100

Slide 100 text

Extract Hidden Concept // inside NotifyPayment function ... if (rPayment.GetCurrentProviderPaymentId() == rProviderPayment.GetProviderPaymentId() && rPayment.IsWaitPay()) { rPayment.Accept(rProviderPayment); } ...

Slide 101

Slide 101 text

Slide 102

Slide 102 text

Extract Hidden Concept Payment ProviderPayment IPaymentAcceptingPolicy *

Slide 103

Slide 103 text

Extract Hidden Concept // inside NotifyPayment function IPaymentAcceptingPolicy* paymentAcceptingPolicy; ... if (paymentAcceptingPolicy->IsAllowedToAccept( rPayment, rProviderPayment)) { rPayment.Accept(rProviderPayment); } ...