architecture-patterns

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