Handling Cross-Cutting Concerns

In software development, cross-cutting concerns are aspects of a system that affect many parts of the application but are not part of its core business logic. Think of them as system-wide services.

• Logging: Recording events for debugging or auditing.
• Authentication: Verifying a user's identity.
• Authorization: Determining what an authenticated user can do.
• Caching: Storing frequently accessed data for faster retrieval.
• Transaction Management: Ensuring data consistency across multiple operations.

Clean Architecture emphasizes keeping your core business logic (Entities and Use Cases) independent of external frameworks and delivery mechanisms. This is enforced by the Dependency Rule: dependencies must only flow inwards.

The challenge arises because cross-cutting concerns often rely on specific external frameworks (e.g., a logging library, a security framework). How can we implement these concerns without violating the Dependency Rule and coupling our core logic to external details?