Domain-Centric Design - nTier

Definition

• The problem-space of your application is its domain
• The objects you design to model the domain are domain objects
  • Also referred to as model objects of the model
• Domain objects
  • Encapsulate application business logic and rules
  • Maintain any state required to do so
  • Do not depend on external infrastructure concerns

Dependency Inversion Principle (DIP)

High-level modules should not depend on low level modules. Both should depend on abstractions

Abstractions should not depend on details. Details should depend on abstractions.

Refactoring Goal: Onion Architecture

Simply

Onion Architecture Principles

• All code depends on layers closer to center
• Domain model ad center
• Inner layers define interfaces; outer layers implement these interfaces
• Layered behaviour around the domain model
• Infrastructure and I concerns pushed to edge
  • Depend on Application Core, not vice versa

Folder / Project Structure

• ProjectName.Core (Not referencing any other projects)
• ProjectName.Infrastructure (Ref : Core)
• Project.Website (Ref : Core, Infrustructure)
• Project.DAL
• Project.BLL