Layered Architecture
Three Layers
Controller → Service → Repository → Database
↑ ↑ ↑
HTTP Business Data
Handling Logic Access
Responsibilities
| Layer | Responsibility |
|---|---|
| Controller | HTTP handling, validation |
| Service | Business logic, transactions |
| Repository | Data access, queries |
Key Points
- Understanding Controller-Service-Repository is essential for production systems
- Always consider scalability and maintainability
- Test thoroughly before deploying to production
- Monitor performance and set up alerting
Common Patterns
- Validation: Always validate input at the boundary
- Error Handling: Use structured error responses
- Logging: Log key events for debugging
- Testing: Unit, integration, and load tests
- Documentation: Keep docs updated with code changes
Architecture Patterns
Patterns
- Layered: Traditional
- Microservices: Distributed
- Event-Driven: Async
- Serverless: FaaS
Principles
- Single Responsibility
- loose coupling
- High cohesion
- Separation of concerns
Best Practices
- Document decisions
- Use ADRs
- Consider trade-offs
- Design for change
Key Points
- Understanding Controller-Service-Repository is essential for production systems
- Always consider scalability and maintainability
- Test thoroughly before deploying to production
- Monitor performance and set up alerting
Common Patterns
- Validation: Always validate input at the boundary
- Error Handling: Use structured error responses
- Logging: Log key events for debugging
- Testing: Unit, integration, and load tests
- Documentation: Keep docs updated with code changes
Practice Problems
Design and implement a solution for Controller-Service-Repository in a backend system. Consider scalability, error handling, and production readiness.
Solution
// Controller-Service-Repository implementation
// Key aspects: validation, error handling, logging, testing
public class ControllerServiceRepository {
// Production-ready implementation
}Identify and handle edge cases for Controller-Service-Repository. What happens under high load, with invalid input, or during failures?
Solution
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotencyWrite a testing strategy for Controller-Service-Repository. Include unit tests, integration tests, and performance tests.
Solution
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injectionQuiz
1. Controller handles?
2. Service contains?
3. What is the primary purpose of Controller-Service-Repository?
4. What is a common mistake when implementing Controller-Service-Repository?
Flashcards
Question
Controller handles?
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Answer
HTTP requests/responses
Question
Service contains?
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Answer
Business logic and transactions
Question
What is Controller-Service-Repository?
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Answer
Controller-Service-Repository is a key concept in backend development.
Question
When to use Controller-Service-Repository?
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Answer
Use Controller-Service-Repository when building production systems that require reliability, scalability, and maintainability.
Question
Controller-Service-Repository best practices
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Answer
Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.
Revision Notes
Key Takeaways
- 1.Controller: HTTP handling
- 2.Service: business logic, transactions
- 3.Repository: data access
- 4.Separation of concerns
Interview Tips
- •Design layered architecture
- •Apply separation of concerns
Cheat Sheet
Layered Architecture
- Controller: HTTP handling
- Service: business logic
- Repository: data access
- Separate concerns