Clean Architecture in .NET

Introduction

Clean Architecture is a software design approach that promotes maintainability, testability, and flexibility by separating business logic from implementation details. In .NET applications, this architecture helps build robust, scalable systems that can evolve over time without major refactoring.

Core Principles

Key Benefits:

• Separation of Concerns: Isolates business logic from infrastructure and UI
• Testability: Enables focused unit testing of core logic
• Maintainability: Reduces ripple effects from changes
• Flexibility: Allows swapping implementations without changing core logic

Architecture Layers

1. Domain Layer

• Contains core business logic and entities
• Defines interfaces for external interactions
• Completely independent of other layers

2. Application Layer

• Implements use cases and application logic
• Coordinates data flow between layers
• Depends only on Domain layer

3. Infrastructure Layer

• Implements persistence, external services
• Provides concrete implementations of Domain interfaces
• Depends on Domain and Application layers

4. Presentation Layer (Web API)

• Handles HTTP requests/responses
• Contains controllers and DTOs
• Depends on Application layer

Implemented Features

Core Libraries:

• ✅ MediatR (CQRS pattern)
• ✅ Entity Framework Core
• ✅ Dapper (for optimized queries)
• ✅ AutoMapper (object mapping)
• ✅ FluentValidation
• ✅ Serilog (structured logging)

Security:

• ✅ JWT Authentication
• ✅ .NET Identity
• ✅ BCrypt.NET (password hashing)

API Features:

• ✅ Swagger/OpenAPI documentation
• ✅ Health Checks
• ✅ OpenTelemetry (distributed tracing)
• ✅ MiniProfiler (performance analysis)

Additional Components:

• Caching (Cache Manager)
• Email (MailKit, FluentEmail)
• File Processing (EPPlus, CsvHelper)
• Testing (Moq, Bogus)
• Resilience (Polly)

Implementation Details

Core Libraries

Library	Purpose	Layer	NuGet
MediatR	CQRS pattern	Application	MediatR
AutoMapper	Object mapping	Application	AutoMapper
FluentValidation	Validation logic	Domain	FluentValidation

Data Access

Library	Purpose	Layer	NuGet
EntityFramework Core	ORM	Infrastructure	EFCore
Dapper	High-performance queries	Infrastructure	Dapper
EFCore.SqlServer	SQL Server provider	Infrastructure	EFCore.SqlServer

API Features

Library	Purpose	Layer	NuGet
Swagger	API documentation	WebApi	Swashbuckle
Serilog	Structured logging	Cross-layer	Serilog
HealthChecks	System monitoring	Infrastructure	AspNetCore.HealthChecks

Security

Library	Purpose	Layer	NuGet
JWT Bearer	Token authentication	WebApi	JwtBearer
ASP.NET Identity	User management	Infrastructure	Identity
BCrypt.NET	Password hashing	Domain	BCrypt

Best Practices

1. Keep Architecture Simple

   • Avoid unnecessary complexity
   • Follow SOLID principles

2. Layer Independence

   • Strict dependency rules (inner layers don't know about outer ones)
   • Depend on abstractions, not concretions

3. Clean Code

   • Meaningful naming conventions
   • Small, focused classes/methods
   • Consistent coding style

4. Continuous Refactoring

   • Regular code quality reviews
   • Incremental improvements
   • Technical debt management

5. Layer Isolation

   • Inner layers never reference outer layers
   • Dependencies flow inward only

6. Testability

   • 90%+ unit test coverage for Domain/Application
   • Mock all external dependencies

7. Performance

   • Dapper for read-heavy operations
   • Caching with CacheManager
   • Query optimization with MiniProfiler

Getting Started

1. Clone the repository
2. Configure connection strings in appsettings
3. Run database migrations
4. Start the WebApi project