Hexagonal Architecture

1. Introduction

Hexagonal Architecture, also known as Ports and Adapters, is a software design pattern that aims to create loosely coupled application components. It allows for better separation of concerns by isolating the core logic from external systems.

2. Key Concepts

• **Core Application Logic**: The heart of the application, which is independent of external frameworks and technologies.
• **Ports**: Interfaces that define how the core logic interacts with the outside world.
• **Adapters**: Implementations of the ports that connect the core logic to external systems (e.g., databases, APIs).

3. Components

Hexagonal architecture consists of three main components:

1. Application Core: Contains business logic and domain entities.
2. Ports: Define the interfaces through which the application communicates.
3. Adapters: Realize the ports and connect the application to external services.

4. Implementation

Here’s a basic implementation structure:

                ├── src
                │   ├── application
                │   │   └── ApplicationService.java
                │   ├── domain
                │   │   └── Model.java
                │   ├── ports
                │   │   ├── InputPort.java
                │   │   └── OutputPort.java
                │   └── adapters
                │       ├── RestAdapter.java
                │       └── DatabaseAdapter.java
                

Each layer communicates only through the defined ports, ensuring that the core logic remains isolated from external dependencies.

5. Best Practices

• Keep the core logic agnostic to technology choices.
• Define clear interfaces for ports.
• Use dependency injection to manage adapters.
• Write tests for core logic without needing external systems.

6. FAQ