architecture-patterns

# Architecture Patterns Master proven backend architecture patterns including Clean Architecture, Hexagonal Architecture, and Domain-Driven Design to build maintainable, testable, and scalable systems. ## When to Use This Skill - Designing new backend systems from scratch - Refactoring monolithic applications for better maintainability - Establishing architecture standards for your team - Migrating from tightly coupled to loosely coupled architectures - Implementing domain-driven design principles - Creating testable and mockable codebases - Planning microservices decomposition ## Core Concepts ### 1. Clean Architecture (Uncle Bob) **Layers (dependency flows inward):** - **Entities**: Core business models - **Use Cases**: Application business rules - **Interface Adapters**: Controllers, presenters, gateways - **Frameworks & Drivers**: UI, database, external services **Key Principles:** - Dependencies point inward - Inner layers know nothing about outer layers - Business logic independent of frameworks - Testable without UI, database, or external services ### 2. Hexagonal Architecture (Ports and Adapters) **Components:** - **Domain Core**: Business logic - **Ports**: Interfaces defining interactions - **Adapters**: Implementations of ports (database, REST, message queue) **Benefits:** - Swap implementations easily (mock for testing) - Technology-agnostic core - Clear separation of concerns ### 3. Domain-Driven Design (DDD) **Strategic Patterns:** - **Bounded Contex...