What is Clean Architecture

08/10/2023 Version 1.00

Clean Architecture is a sophisticated and intuitive approach to structuring software systems. It's a methodology that prioritizes separating concerns by dividing a system into layers, each with distinct responsibilities, ensuring the system remains adaptable and maintainable over time. A few fundamental principles characterize this approach:

Framework Independence:

1. The architecture is not reliant on specific software libraries, making it easier to use frameworks as tools without being constrained by them
2. Testability: Business rules can be tested without dependencies on UI, database, web server, or other external elements.
3. UI Independence: The user interface can be changed or replaced without impacting the underlying system.
4. Database Independence: It allows flexibility to change the database system without affecting business rules.
5. External Agency Independence: The business rules don't need to know anything about external interfaces or data formats.

The architecture is visualized as concentric circles, each representing different layers of the software:

1. Entities: These encapsulate enterprise-wide business rules and are used across various applications.
2. Use Cases: This layer contains application-specific business rules.
3. Interface Adapters: This layer adapts data between the format used by use cases and entities and the format needed by external agencies like databases or web interfaces.
4. Frameworks and Drivers: The outermost layer, generally containing tools like databases and web frameworks.
5. A fundamental rule in this architecture is the Dependency Rule: Source code dependencies always point inward. No inner circle knows anything about the outer circles, preserving the independence and replaceability of external components.
6. This architecture ensures that software systems are built in a way that is independent of external agencies, frameworks, and interfaces, making them more robust, adaptable, and easier to maintain. The simplicity and intuitive nature of the Clean Architecture make it an excellent choice for a wide range of software development projects.