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Microservicessystem_design~12 mins

Domain-Driven Design (DDD) basics in Microservices - Architecture Diagram

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System Overview - Domain-Driven Design (DDD) basics

This system uses Domain-Driven Design (DDD) principles to organize a complex business application into multiple microservices. Each microservice represents a specific domain or subdomain, encapsulating its own data and logic. The goal is to improve maintainability, scalability, and clear separation of concerns.

Architecture Diagram
User
  |
  v
API Gateway
  |
  +----------------+----------------+----------------+
  |                |                |
Order Service   Payment Service  Inventory Service
  |                |                |
Order DB       Payment DB       Inventory DB
  |                |                |
Cache           Cache           Cache
Components
User
client
Initiates requests to the system
API Gateway
api_gateway
Routes user requests to appropriate domain microservices
Order Service
service
Handles order domain logic and data
Payment Service
service
Manages payment domain logic and data
Inventory Service
service
Manages inventory domain logic and data
Order DB
database
Stores order domain data
Payment DB
database
Stores payment domain data
Inventory DB
database
Stores inventory domain data
Cache
cache
Speeds up read operations for each service
Request Flow - 12 Hops
User → API Gateway
API Gateway → Order Service
Order Service → Cache
Order Service → Order DB
Order Service → Payment Service
Payment Service → Payment DB
Payment Service → Cache
Order Service → Inventory Service
Inventory Service → Inventory DB
Inventory Service → Cache
Order Service → API Gateway
API Gateway → User
Failure Scenario
Component Fails:Order DB
Impact:Order service cannot persist new orders, causing order creation failures. Cached data may still be served for reads but will be stale.
Mitigation:Use database replication and failover to a standby DB. Implement retry logic and circuit breakers in the order service.
Architecture Quiz - 3 Questions
Test your understanding
Which component routes user requests to the correct domain microservice?
AAPI Gateway
BCache
COrder Service
DInventory DB
Design Principle
This architecture demonstrates the DDD principle of dividing a complex system into bounded contexts represented by microservices. Each service owns its domain logic and data, communicating through well-defined interfaces. This separation improves scalability, maintainability, and clarity of the system.