Microservices (Architecture)

The core concepts of microservice architecture are:

• Definition: Microservices are an architectural style where applications are structured as a collection of loosely coupled, independently deployable services.
• Key Architectural Layers:
  • Presentation Layer: Handles user interface and client interactions
  • Business Process Layer: Contains core business logic and workflows
  • Data Access Layer: Manages data storage and retrieval
• Communication Patterns:
  • Direct Client-to-Service: Simple point-to-point communication
  • Service-Oriented Architecture: Centralized message routing through an Enterprise Service Bus
  • API Gateway/Proxy: Modern approach with distributed service mesh

Helpful images from Microservices Udemy Course.

Traditional approach where all application components are tightly coupled in a single deployable unit. All layers share the same database and deployment lifecycle.

graph TB
    subgraph "Monolithic Architecture"
        M[Single Application
- Presentation Layer
- Business Logic
- Data Access Layer]
        DB1[(Database)]
        M --> DB1
    end
  

Introduces service separation but relies on a centralized Enterprise Service Bus for communication, creating a potential bottleneck and single point of failure.

graph TB
    subgraph "Service-Oriented Architecture (SOA)"
        ESB[Enterprise Service Bus]
        S1[Service A] --> ESB
        S2[Service B] --> ESB
        S3[Service C] --> ESB
        ESB --> S4[Service D]
        ESB --> S5[Service E]
    end
  

Fully distributed approach where each service owns its data and communicates through well-defined APIs. The API Gateway provides a single entry point while services communicate directly with each other when needed.

graph TB
    subgraph "Microservices Architecture"
        API[API Gateway]
        
        MS1[User Service]
        MS2[Order Service]
        MS3[Payment Service]
        MS4[Inventory Service]
        MS5[Notification Service]
        
        DB2[(User DB)]
        DB3[(Order DB)]
        DB4[(Payment DB)]
        DB5[(Inventory DB)]
        
        API --> MS1
        API --> MS2
        API --> MS3
        API --> MS4
        API --> MS5
        
        MS1 --> DB2
        MS2 --> DB3
        MS3 --> DB4
        MS4 --> DB5
        
        MS2 -.-> MS1
        MS2 -.-> MS3
        MS2 -.-> MS4
        MS3 -.-> MS5
    end
  

• Service Boundaries:
  • Each service should have a clear, bounded context
  • Services should be sized appropriately - neither too large (Monolithic) nor too small (nano-services)
  • Data domains often define natural service boundaries
• Technical Considerations:
  • Increased network latency due to service chains
  • Trade-offs between ACID Transactions and eventual consistency
  • Need for robust service discovery and load balancing
  • Importance of fault tolerance and circuit breaking

• Edge Services: Handle external-facing concerns
• Business Process Services: Implement core domain logic
• Data Services: Manage data access and storage
• Gateway Services: Route and aggregate service calls

• Backend: Java, C#, Node.js
• Frontend: JavaScript frameworks
• Data Science: Python
• Each service can use the most appropriate technology for its specific needs

DevOps can influence microservice architecture:

• Continuous Delivery Pipeline (CI/CD):
  1. Business Input drives development
  2. Code development and review
  3. Compilation and testing
  4. Unit test execution
  5. Defect reporting and tracking
• Operational Considerations:
  • Logging and tracing across services
  • Monitoring and alerting
  • Service discovery
  • Configuration management
  • Security and access control

• Keep services autonomous and loosely coupled
• Implement robust error handling and fallback mechanisms
• Use asynchronous communication where possible
• Maintain comprehensive service documentation
• Implement proper versioning strategies
• Consider implementing circuit breakers for fault tolerance

• Increased operational complexity
• Network latency and reliability concerns
• Data consistency across services
• Service discovery and routing
• Monitoring and debugging distributed systems
• Team organization and communication

• Microservices Udemy Course

Origin: Microservices Udemy Course
References: SOA
Created