Onion Architecture vs Clean Architecture

  1. What is the difference between these approaches?

Both architectures revolve around the same idea:

  • The direction of dependencies is toward the center

  • The core contains the domain entities and business rules

  • The core should be independent of any external concerns

The main idea here is controlling coupling. Our domain entities and business rules are at the center of the system. They don’t depend on anything, which is valuable because it makes them stable. Things around the Domain can change, which shouldn’t affect the domain or business rules. Remember, coupling is the degree of interdependence between our modules and components.

Both Clean and Onion architecture strive to achieve the same goals:

  • We have the Domain in both

  • Clean architecture has use cases

  • Onion architecture has domain and application services

  • On the very edges, we have infrastructure concerns

  1. So what’s the difference?

Any differences fade when it’s time to implement this architecture in a project. Another architectural driver you should consider is cohesion. Cohesion refers to the degree to which the elements within a module belong together and work together to achieve a single, well-defined purpose.