A brief introduction to Clean architecture
Clean architecture is a software architecture guideline proposed by Robert C. Martin(Uncle Bob) that aims to build scalable, testable, and maintainable software. It's derived from many architectural guidelines like Hexagonal Architecture, Onion Architecture, etc. over the years.
Clean Architecture concepts
Clean architecture is a software architecture pattern that aims to achieve the following goals:
Independent of frameworks: The core business logic of the application should not be dependent on any specific framework or technology. This makes the application more flexible and easier to maintain.
Testable: The business logic should be easily testable in isolation from the rest of the application.
Maintainable: The code should be well-organized and easy to understand. This makes it easier for devs to make changes to the application without breaking things.
The basic principles of clean architecture are:
Dependency rule: Dependencies should always point inwards.
Abstraction: Use interfaces to abstract away the details of the implementation.
Separation of concerns: Separate the different parts of the application into different layers. This makes the code easier to understand and maintain.
Layers in Clean Architecture
1.Entities
This layer contains enterprise-wide business rules and is independent of the other layers. In OOP, this is the Object with methods and properties that comply with the Encapsulation principle - only inside the Object can change its own state.
Example: Entity could be a User object that contains properties like Age, etc. The Age property can't be less than 1. If we need to change Age, we must write a public function set Age, which is also responsible for checking conditions related to Age.
The business logic of the Entities layer won't care about or depend on the business logic in external layers such as Use Cases. Assuming the user must be 18 years old or older to create an account, the Age attribute rule in Entities remains unchanged.
2.Use cases
This layer contains application-specific business rules and is dependent on the Entity layer.
Example : The use case could be a CreateUser class that contains methods for creating a new user.
The business logic of the Use Case won't care and depends on where the data comes from, what libraries are used as adapters, how the data is presented, etc. Because that is the task of the Interface Adapters layer.
3.Interface Adapters
This layer contains adapters that convert data from the Use Case layer into a format that can be displayed by the user interface
Example: Interface Adapters could be a UserController class that handles HTTP requests and responses for user-related operations.
Thus, the input and output data at the Interface Adapters layer only needs to be sufficient and reasonable. It won't care how specifically the data will be displayed or collected. Because that is the task of the Frameworks & Drivers layer.
4.Frameworks and Drivers
This layer contains frameworks and tools that support the other layers such as devices, web, applications, databases, etc.
Example: An example of this layer could be a Database class that handles database operations for the application.
This table below is to help you quickly keep track of layers in Clean architecture.
| Name | Content | Dependency |
|---|---|---|
| Entities | Core business data and rules. | None |
| Use Cases | Application-specific business rules. | Depends on Entities, independent of Frameworks |
| Interface Adapters | Input and output mechanisms (UI, databases, frameworks). | Depends on Use Cases, independent of Frameworks |
| Framework & Drivers | External tools, frameworks, and technology-specific details. | Depends on Interfaces and Use Cases |
Project structure
🛠️MyAppServiceSolution/
├── #️⃣MyApp.Shared/ - (It contains shared components, which aren't required in Clean architecture. It serves as your common service or packages in the future)
│ └── …
├── #️⃣MyApp.API/
│ ├── 📂Controllers/
│ │ ├── UserController.cs
│ ├── 📂Extentions/ - Contains config extensions for the API layer
│ │ ├── AppExtension.cs
│ ├── Startup.cs
│ └── …
├── #️⃣MyApp.Dtos/
│ ├── 📂Users/
│ │ ├── UserRequestModel.cs
│ │ ├── UserResponseModel.cs
│ └── …
├── #️⃣MyApp.Application/
│ ├── 📂Services/
│ │ ├── 📂Interfaces
│ │ ├── IUserService.cs
│ │ ├── UserService.cs
│ ├── 📂Dtos/
│ │ ├── UserDto.cs
│ └── …
├── #️⃣MyApp.Domain/
│ ├── 📂Entities/
│ │ ├── User.cs
│ ├── 📂Repositories/
│ │ ├── IUserRepository.cs
│ └── …
├── #️⃣MyApp.Infrastructure/
│ ├── 📂Persistence/
│ │ ├── 📂EntityConfigurations
│ │ ├── 📂Migrations
│ │ ├── 📂Repositories/ - Implement interface repositories from MyApp.Domain
│ │ │ ├── UserRepository.cs
│ │ ├── 📂Extentions/ - Contains config extensions for the Infrastructure layer
│ │ │ ├── ModelBuilderExtensions.cs
│ │ ├── MyAppContext.cs
│ └── …
└── #️⃣MyApp.Tests/
├── 📂MyApp.UnitTests/
├── 📂MyApp.IntegrationTests/
Map project structure to Clean Architecture
| Name | Layer | Content |
|---|---|---|
| MyApp.API | Interface Adapters | Could be considered as the entry point for your application, interacting with the application layer. |
| MyApp.Application | Use Cases (Application) | It contains services that implement application-specific business rules. |
| MyApp.Contracts | Interface Adapters | The interface layer for Data Transfer Objects (DTOs) is shared between layers. |
| MyApp.Domain | Entities and Business Rules (Core layer) | It contains business entities, repositories, and repository interfaces. |
| MyApp.Infrastructure | Frameworks & Drivers | It manages the database (persistence), contains external configuration extensions, and implements repository interfaces. |
I'll skeleton Clean Architecture in the next chapter. See ya.
You also reach my blog on medium.com by this link: https://linhvuquach.medium.com/clean-architecture-in-enterprise-application-47d94015c93a
Cheers!
References
- https://betterprogramming.pub/the-clean-architecture-beginners-guide-e4b7058c1165
- https://www.freecodecamp.org/news/a-quick-introduction-to-clean-architecture-990c014448d2/
- https://www.educative.io/blog/clean-architecture-tutorial
- https://developers.redhat.com/articles/2023/08/08/implementing-clean-architecture-solutions-practical-example#a_sample_clean_architecture_implementation
- https://betterprogramming.pub/practicing-clean-architecture-in-c-62fe55aed83c
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