Service
communications
SOA/ESB/EDA/MicroService/CQRS/ES
Bounded Context & Context Mapping
Context
Domain Driven Design
Bounded Context
Dealing with Complexity, Legacy System, Separated Team corp ...
Context
Bounded Context
Context
Why we need Bounded Context ?
As we try to model a larger domain, it gets progressively harder to build a single unified model.
We build model acting as a UbiquitousLanguage
https://martinfowler.com/bliki/BoundedContext.html
Context
Recognize bounded context
Contradiction of entities
Linguistic / Business Capability
Context
For an example
Name, Profile
User
Browsing History
Receiver, Orders
Payer, CreditCardNumber
Member
Lead
Buyer
Payer
Context
For an example
Category, Labels
Product
Price, Promotion
Order
Product
SalesItem
OrderItem
Sku
Inventory
Context
conway laws
"Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization's communication structure."
Conway Laws
Context
autonomy
Every context has its database
Autonomy
Microservice
https://www.slideshare.net/kimKao/2019-0612aws-taipei-summitdeve-day2essential-capabilities-behind-microservices
Context
autonomy
https://medium.com/design-and-tech-co/implementing-domain-driven-design-for-microservice-architecture-26eb0333d72e
Context
find service boundary
4+1 Architectural View Model
https://codeopinion.com/41-architectural-view-model/
codebase/git
cloud infra/cd
communication
functionality
Context
find service boundary
4+1 Architectural View Model
https://codeopinion.com/41-architectural-view-model/
When not everything maps 1:1, that’s when it makes it a bit more challenging finding service boundaries. Focus on the scenarios.
Context
For an example
Which context do User Auth belongs ?
Context
For an example
https://ithelp.ithome.com.tw/articles/10218252/
Context
For an example
Problem-Space & Solution-Space
https://medium.com/@nikhilgupta08/problem-space-vs-solution-space-f970d4ace5c
Context
Domain Driven Design
Context Mapping
Context
Context mapping
Big mud ball /
Continuous Intergration
Context
Shared Kernel
Share models between different context
Order in Shopping context &
Recommendation context
Context Mapping
Context
Customer-Supplier
Automated Acceptance Tests
Downstream is the customer
Context Mapping
Context
Conformist
When upstream has no motivation to supply downstream
Context Mapping
Upstream is good to follow
Context
Anti-corruption Layer
Translate only data but not business logic
FACADE
Like a Service
Context Mapping
Legacy system is usually most valuable in prod.
Context
Open Host Service/
Published Language
Context Mapping
API
Protocol Buff
Context
Open Host Service/
Published Language
Context Mapping
https://zhuanlan.zhihu.com/p/31985410?fbclid=IwAR3Z6cZZtjkI-kLD_f8oJyonx3BlvqLBvu4_LCWn578oflQS_iicqJpSwKk
Context
Separate Way
e.g. Delivery state of Logistics (outsource), excel ...
Context Mapping
When we don't consider further integrations
Context
Context Mapping
Context
Context Mapping
The level of control
The cost of coordination
Context
Context Mapping
In Lower the integration mode
Lead to less communicate
More duplicated code
Context
Context Mapping
Big Context
Small Context
https://xiaoyue26.github.io/2019/07/22/2019-07/%E9%A2%86%E5%9F%9F%E9%A9%B1%E5%8A%A8%E8%AE%BE%E8%AE%A1-%E7%AC%AC7-17%E7%AB%A0%E7%AC%94%E8%AE%B0/
One Cohesive model, more clear & less transfer cost
Less abstract design required
More flexible for specific demands
Context
Context Mapping
Follow the reality to build bounded context, not the ideal.
Context
Context Mapping
Less destruction of models & less works
Context
Context Mapping
Merge Bounded Context
Separate way -> Shared kernel
Focus on the duplicated subdomain
p.398
Map the term
Start from the small and easy part
Context
Context Mapping
Merge Bounded Context
Shared kernel ->
Continuous Intergration
One big team or Two small team (which is good)
Be careful about core domain
Context
Context Mapping
Merge Bounded Context
Eliminating Legacy System
1. Pick one functionality from legacy to new system
2. Make sure we have enough auto tests
3. Implementation
Context
Context Mapping
Distillation
Don't split contexts by any other thing isn't related to logic
Context
Context Mapping
Context
Context Mapping
Insurance Company Example
https://github.com/ContextMapper/context-mapper-examples/tree/master/src/main/cml/insurance-example
Context
Context Mapping
Bounded Context vs Subdomain
Implementation & protection of models
Represent the definition for subdomain
Business capability
Implementation
How we carry out these concepts
Concept v.s. Architecture
Service-Oriented Architecture
Implementations
From concepts to implementations
Enterprise Service Bus
Implementations
From concepts to implementations
Event-Driven Architecture
Implementations
From concepts to implementations
Microservice
Implementations
From concepts to implementations
中台模式
Implementations
From concepts to implementations
CQRS
Implementations
From concepts to implementations
Event Sourcing
Implementations
From concepts to implementations
Event Communications
How distributed system communicate to each others
Choreography
v.s. Orchestration
Choreography
Orchestration
&
Event communications
How distributed system communicate to each others
command
events
https://microservices.io/patterns/data/saga.html
Event communications
How distributed system communicate to each others
https://solace.com/blog/microservices-choreography-vs-orchestration/
Event communications
How distributed system communicate to each others
TypeScript Ver. POC: https://github.com/guAnsunyata/ts-tram-saga
Event communications
How distributed system communicate to each others
https://www.youtube.com/watch?v=Fso2OyguRuQ
Event communications
How distributed system communicate to each others
https://www.youtube.com/watch?v=Fso2OyguRuQ
Message Queue Server
message queue
Challenges
https://github.com/OptimalBits/bull
Message Queue Server
message queue
Compare to all potential solutions
NATS
Introduce NATS
NATS
Introduce NATS
NATS
Introduce NATS
NATS
Introduce NATS
Subject
Subscription
Queue Group
Durable Name
Decoupling
Decouping
Help us more efficiency
A Microservice way
Decoupling
Help us more efficiency
Event Sourcing (CDP)
ML use cases
Help us more efficiency
Domain Event
https://github.com/CodelyTV/php-ddd-example/blob/master/src/Mooc/Courses/Domain/Course.php
ML use cases
Help us more efficiency
Model
Domain Driven Design
Model Evolution
Model
model
https://www.jianshu.com/p/39c557f5b87f
Model
model
Model
model
Model
model
Model
model
Model
model
https://ithelp.ithome.com.tw/articles/10218943
Model
model
Model
model
Location
Model
model
Model
model
Model
Domain Driven Design
Choosing context mapping
External System
Different Model
Deployment
Event/Command - Cross Domain communications
By guansunyata
