Part 01 - Clean Architecture Overview

Clean Architecture: Maintainable, Testable, and Scalable Applications

Originally Posted on: https://www.arunyadav.in/codehacks/blogs/post/20/part-01-clean-architecture-overview

In software development, creating a well-designed and organized application is crucial for success. Clean Architecture is a software design principle that can help you achieve this goal by separating an application into distinct parts. This makes it easier to maintain, test, and scale the application over time.

The main idea behind Clean Architecture is to keep the business logic of an application isolated from external factors, such as presentation, infrastructure, and persistence. This separation of concerns makes it easier to change and maintain the application, as well as test it without affecting other parts of the code.

Clean Architecture consists of several circles or layers, each with a specific responsibility. The innermost circle is the business logic, which is the core of the application. This layer is isolated from external factors and communicates with other layers through well-defined interfaces. The business logic should not depend on the outer layers, and instead should rely on abstractions.

The next layer is the interface adapters, which are responsible for converting data between the business logic and the outer layers. This layer includes things like presentation logic, data access, and infrastructure.

Finally, the outer layer is the frameworks and drivers, which are responsible for providing external services to the application. This layer includes things like databases, web servers, and operating systems.

Let's understand by Onion View

The flow of dependencies in the diagram moves towards the center. The centermost point is referred to as the Application Core, which acts as the nucleus of the diagram and is not dependent on any other layers. The entities and interfaces occupy the central position while domain services, which provide implementation to the central interfaces, surround them. The UI and Infrastructure layers, located on the exterior, are both dependent on the Application Core.

Let's understand by Horizontal View

In the clean architecture, the direction of solid arrows indicates compile-time dependencies, while the dashed arrow signifies a dependency that only exists at runtime. The UI layer interacts with the interfaces specified in the Application Core during compilation, without having knowledge of the concrete implementations in the Infrastructure layer. At runtime, these implementations become necessary for the operation of the app, and must be connected to the Application Core interfaces through dependency injection.