dotnet-development

Domain-Driven Design in .NET organizes your application into Domain, Application, and Infrastructure layers, with business logic centered on aggregates and repositories. This separation ensures maintainability, testability, and alignment with business domains, reducing technical debt and making refactoring easier as requirements evolve.

SOLID principles guide C# class design: Single Responsibility keeps classes focused on one reason to change, Open/Closed allows extension without modification, Liskov Substitution ensures derived types are substitutable, Interface Segregation prevents fat interfaces, and Dependency Inversion decouples high-level modules from low-level ones. Applying these reduces coupling and improves testability.

ASP.NET Core REST APIs pair controllers with EF Core data access, using async/await with cancellation tokens, constructor injection for dependencies, and boundary validation at entry points. Organize code into Domain, Application, and Infrastructure folders; use repositories and domain events to maintain clean architecture and support testing with xUnit and Moq.

Yes. DDD aggregates define transactional boundaries in microservices, while repositories abstract data access. This pattern works well with ASP.NET Core controllers handling HTTP requests and EF Core managing persistence, enabling scalable, maintainable microservices that enforce business rules and maintain domain consistency.

Use xUnit for unit and integration tests, Moq for mocking dependencies, and FluentAssertions for readable assertions. Test domain entities and aggregates in isolation, verify repository behavior with test databases, and validate controller endpoints. This approach ensures business logic correctness and architecture compliance across layers.

Layered architecture with Domain, Application, and Infrastructure boundaries suits applications with complex business logic, multiple stakeholders, or long-term maintenance needs. It excels when domain rules change frequently or teams need clear separation of concerns, though it adds overhead for simple CRUD applications where simpler patterns may suffice.