Hexagonal Architecture Guide

Hexagonal Architecture (also known as Ports & Adapters) organizes code so that business logic is at the center, isolated from all external concerns. The core application communicates with the outside world only through well-defined interfaces (ports), and concrete implementations (adapters) plug into those interfaces.

Table of Contents

1. Core Principles
2. Directory Structure
3. The Domain Layer
4. Ports — Defining Contracts
5. Adapters — Implementing Contracts
6. The Application Layer (Use Cases)
7. Handlers — Primary Adapters
8. Dependency Injection & Wiring
9. Cross-Cutting Concerns with the Decorator Pattern
10. Error Handling Strategy
11. Configuration Management
12. Testing Strategy
13. Dependency Flow Rules