C# Clean Architecture

Clean Architecture is a software architecture paradigm that separates concerns into layers, where each layer has a single responsibility. It is a way to design and organize a software system that is easy to maintain, flexible, and testable. In this tutorial, we'll discuss the principles of Clean Architecture and show how to implement it in C#.

Principles of Clean Architecture

The principles of Clean Architecture are based on the SOLID principles of software design. The main idea is to separate concerns into layers and make sure that each layer has only one reason to change. The layers of Clean Architecture are:

1. Presentation Layer: This layer handles user input/output and user interface concerns. It should be free of business logic.

2. Application Layer: This layer contains use cases or business rules that depend on the input from the presentation layer.

3. Domain Layer: This layer contains the core business logic. It is independent of any external concerns, such as the database or user interface.

4. Infrastructure Layer: This layer contains implementations of the interfaces defined in the domain layer. It includes the database, web services, and other external dependencies.

Example

Here is an example implementation of Clean Architecture in C#:

namespace MyApplication.Domain {
   public class User {
      public int Id { get; set; }
      public string Name { get; set; }
      public string Email { get; set; }
      public string PasswordHash { get; set; }
   }
}

namespace MyApplication.Infrastructure {
   public class UserRepository {
      public User GetUserById(int id) {
         // implementation details here
         return user;
      }
      
      public User CreateUser(User user) {
         // implementation details here
         return user;
      }
   }
}

namespace MyApplication.Application {
   public class UserService {
      private UserRepository _userRepository;
      
      public UserService(UserRepository userRepository) {
         _userRepository = userRepository;
      }
      
      public User GetUserById(int id) {
         return _userRepository.GetUserById(id);
      }
      
      public User CreateUser(User user) {
         // business rules here
         return _userRepository.CreateUser(user);
      }
   }
}

namespace MyApplication.Presentation {
   public class UserController {
      private UserService _userService;
      
      public UserController(UserService userService) {
         _userService = userService;
      }
      
      public User GetUserById(int id) {
         return _userService.GetUserById(id);
      }
      
      public User CreateUser(User user) {
         return _userService.CreateUser(user);
      }
   }
}

In this example, the domain layer contains a User object that represents a user in the system. The infrastructure layer contains a UserRepository class that implements the interface defined in the domain layer for manipulating users in the database. The application layer contains a UserService class that depends on the UserRepository to get and create users. Finally, the presentation layer contains a UserController class that depends on the UserService to interact with the user interface.

Explanation

In Clean Architecture, each layer has only one responsibility, and each layer depends only on the layer directly below it. This makes the system easy to maintain, flexible, and testable. The layers are decoupled, which means that changes to one layer don't affect the others.

In the example above, the implementation details of each layer are hidden from the layers above, which makes it easier to change the implementation without affecting the other layers. For example, you could switch from using a SQL database to a NoSQL database, and only the infrastructure layer would need to change.

Use

Clean Architecture is useful for maintaining large and complex software systems. It allows you to design and organize your system in a way that makes it easy to maintain, flexible, and testable. Clean Architecture can help you create a system that is well-organized, easy to understand, and easy to modify.

Important Points

• Each layer in Clean Architecture has only one responsibility.
• Each layer depends only on the layer directly below it.
• The layers are decoupled, which means that changes to one layer don't affect the others.
• The implementation details of each layer are hidden from the layers above.

Summary

In this tutorial, we discussed the principles of Clean Architecture and showed how to implement it in C#. We covered the example, explanation, use, important points, and summary of Clean Architecture in C#. With this knowledge, you can now design and organize your software system in a way that makes it easy to maintain, flexible, and testable.