This document discusses domain-driven design architecture and implementation. It provides an example of an insurance company domain model with entities like customer management, self-service, policy management, debt collection, risk management, and printing. It then covers architectural styles and patterns like layered architecture, dependency inversion, APIs, SPIs, hexagonal architecture, event-driven architecture, CQRS, event sourcing, and infrastructure technologies like Kafka. The key messages are that domain-driven design prioritizes separating domains and concerns through principles like SRP, OCP and LSP, and architectural styles should follow SOA principles and use appropriate integration patterns.

1. IMPLEMENTATION
DOMAIN-DRIVEN DESIGN CH04
ARCHITECTURE
Presenter : HarryYao
Date : 2019/05/08

2. Recap
■ Strategic Modeling
– Architecture
■ Tactical Modeling

3. Example – Insurance Company
■ Customer Management
– 客戶資料管理,客戶個資
■ Customer Self-Service Management
– 客戶自助服務,線上個資維護,線上投保,保單查詢,理賠進度查詢…
■ Policy Management
– 保險契約管理,新契約客戶初審計算費率(Risk Management)
■ Debt Collection
– 保費繳收與依契約理賠出險
■ Risk Management
– 風險管理,提供新契約風險評估報告
■ Printing Context
– 提供API供訪問,可列印債務、保險契約、客戶資料或報表
Round 1. 每人一張白報紙
架構規劃 10min
Scenario
客戶在線上網上投保旅遊平安險.
保險專員印出保單讓主管進行簽核完成投保.

4. SaaSOvation CIO Recap
Core is always DDD.
■ Client-Server
■ Layered
■ DIP ( UI, Infrastructure)
■ REST
■ SOA
■ CQRS
■ Pipe and Filter (Message Queue , Event Streaming)
■ Event Sourcing

5. About 2002~2006
User Interface
Application Service
Domain Service, Domain Model
Infrastructure

6. LayeredArchitecture
User Interface
UI/UX, Presentation
Application Service
Cooperate with each layer
ex. Data-in from User Interface,
Create/Update Data to infrastructure
Domain Service, Domain Model
Business Logic , Entity
Infrastructure
Repository , Database, File , Service

7. LayeredArchitecture + DIP
High-level
Low-level
Interface(API)
Interface(SPI)
Decoupling FromTechnology
MockTesting
Application Isolate
Domain Isolate

8. Supplement : Dependency Inversion
Principle (DIP)
Buy Gift
Gift
禮物 Layer
交往 Layer
Buy Gift
Gift
<<I>>
Buy Gift
男友需要了解
禮物,才能買
男友不須了解
禮物,有錢可以
買就好=>
有錢任性

9. Supplement : API & SPI
Application Programming Interface(API)
■ theAPI is the description of classes/interfaces/methods/... that you call and use to achieve a goal
Service Provider Interface(SPI)
■ the SPI is the description of classes/interfaces/methods/... that you extend and implement to achieve
a goal
differently,
■ theAPI tells you what a specific class/method does for you and
■ the SPI tells you what you must do to conform.

10. Supplement : Services/Systems in
Layered
API
Application
Layer
Domain
Layer
SPI
Infrastructure
Layer
API Application
Layer
Domain
Layer
SPI
Infrastructure
Layer
API
Application
Layer
Domain
Layer
SPI
Infrastructure
Layer
API Application
Layer
Domain
Layer
SPI
Infrastructure
Layer
UI
UI
UI
SystemA
Service C
System B
System D
API Application
Layer
Domain
Layer
SPI
Infrastructure
Layer
Service E

11. Supplement : ESB (Enterprise Service Bus)
 A Product
 well implement for SOA
 Layered-Style
 API & SPI Integration
 For Services or Resources Request
In Layered Follow SOA Principles

12. HexagonalArchitecture (2005~)
User Interface
UI/UX, Presentation
Application Service
Cooperate with each layer
ex. Data-in from User Interface,
Create/Update Data to infrastructure
Domain Service, Domain Model
Business Logic , Entity
Infrastructure
Repository , Database, File , Service

13. SOAP, REST, Message… in Hexagonal
Follow SOA Principles Port & Adapter

14. SOAP , REST… in Layered
REST
API
SOAP
API

15. SOAP(Simple ObjectAccess Protocol)
■ Expose & Encapsulate Service
REST(Representational StateTransfer)
• Expose & Encapsulate Resource
• Stateless communication
• Idempotent ( GET,PUT,DELETE)
• Richardson Maturity Model(Martin
fowler)

16. Supplement : HexagonalArchitecture
Reference

17. Supplement : Hexagonal
Architecture(cont’), DIP
Primary/Driving
API
Adapter Pattern
Secondary/Driven
SPI
Bridge/Strategy/Command… Pattern

18. Supplement : HexagonalArchitecture

19. CRUD
■ Model for Update & Query
■ Performance: Resource Lock ,Transaction
Lock
■ Security : Access Control, data masking…
private int i = 0;
private int Increase(int value)
{
i += value;
return i;
}

20. CQS( Command-Query Separation)
■ Command : no return , but change state.
■ Query : return data, no change state.
■ Log shipping , ETL for Reporting DB
private int i = 0;
private void Increase(int value)
{
i += value;
}
private int GetValue()
{
return i;
}

21. CQRS ( Command-Queries
Responsibility Segregation)■ Query Processor : basic SQL
■ Query Model : only data for display (View)
■ Command Processor: get instance of
aggregates from repository and publish
events ,let Event Subscriber update Query
Model(idempotent)
■ Eventually ConsistentQuery Model
Query Login
Success Count
Login Success
Login Success
Event
Increase Login
Success Count
Login Success
Event

22. Event-Driven Architecture

23. Sample : cat
■ cat phone_numbers.txt | grep 303 | wc –l
■ 3
■ Services/Systems in Hexagonal
Filters
PhoneNumberFinder
MatchedPhoneNumberCounterPhoneNumbersPublisher
<<event>>
AllPhoneNumbersListed
<<event>>
PhoneNumbersMatched
<<event>>
MatchedPhoneNumbersCounted
PhoneNumberExecutive

24. Saga (Long running
time process)
■ ProcessManager
■ Transaction-like
■ Concurrency process
■ Commit or Rollback
3 of 15 phone numbers matched on July 15, 2012 at 11:27
PM
15 phone numbers 3 phone numbers matched

25. Design a Long Running Process (Saga)
Method1
■ Executive create aTracker to record
■ passively time-check when event is
handling or
■ active time-check by timer.

26. Design a Long Running Process(Cont’)
Aggregate ( Executive &Tracker )
begin
done
1
2
3
3
Method2
Method3

27. CQRS + Event Sourcing
■ ChangeTracking objects and the value
produced in our system
■ Patch the event store with new or
modified events that fix problem
■ Undo and redo changes
■ “what if” questions , simulate past or
virtual scenario .

28. CQRS + Event Souring in Layered Style
Domain Layer
Infrastructure Layer
User Interface Layer
Application Layer
Application Layer

29. Data Fabric and Grid-Based Distributed
Computing high-performance computing system
consisting of loosely coupled storage,
networking and parallel processing functions linked
by high bandwidth interconnects…

30. Kafka (2011~)
• Data(Partition) Replication ,
Leader down <- Follower raise
• Guaranteed Delivery
• Eventual Consistency
• Continues Queries (Subscribe), Streaming

31. Conclusion
■ SRP=> Separation of Concern
■ OCP=>open to add adapter , port
■ LSP=>When Implement API , SPI , follow base contract
■ ISP=>Expose & Encapsulate Service or Resource
■ DIP=> Inverse of Control, Decoupling
■ REST(Resource),SOAP(Service),Message(Event), CQRS(Event)…
in Layered/Hexagonal…
follow SOA… principles
■ Modern Infrastructure Support

32. Example – Insurance Company
■ Customer Management
– 客戶資料管理,客戶個資
■ Customer Self-Service Management
– 客戶自助服務,線上個資維護,線上投保,保單查詢,理賠進度查詢…
■ Policy Management
– 保險契約管理,新契約客戶初審計算費率(Risk Management)
■ Debt Collection
– 保費繳收與依契約理賠出險
■ Risk Management
– 風險管理,提供新契約風險評估報告
■ Printing Context
– 提供API供訪問,可列印債務、保險契約、客戶資料或報表
Round 2. 每組一張白報紙
架構規劃 15min
各組分享 3~5min
Scenario
客戶在線上網上投保旅遊平安險.
保險專員印出保單讓主管進行簽核完成投保.