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Clean Architecture vs Onion Architecture

Service interfaces are maintained distinct from their implementation on this layer to ensure loose coupling and separation of concerns. In this article, we will cover the onion architecture using the ASP.Net 6 Web API. Onion architecture term is introduced by Jeffrey Palermo in 2008. Onion architecture solves common problems like coupling and separation of concerns.

onion architecture

Around the domain layer are other layers, with more behaviors. This is another variant that I have noticed in many huge solutions. Let’s say you have around 100 interfaces and 100 implementations.

C# vs Java

Based on the DDD model, we’ve created onion architecture (aka hexagonal or clean architecture). The obvious advantage of the Onion architecture is that our controller’s methods become very thin. We moved all of the important business logic into the Service layer. However, in the OnModelCreating method, we are configuring our database context based on the entity configurations from the same assembly. There are more examples, but hopefully, you get the idea. Using dependency inversion throughout the project, depending on abstractions (interfaces) and not the implementations, allows us to switch out the implementation at runtime transparently.

onion architecture

In the WebApi Project, Properties drill down, you can find a launchsettings.json file. This file holds all the configurations required for the app launch. Thus, the swagger will open up by default every time you run the application. We will have to register Swager within the application service container. Navigate to ../Startup.cs and add these lines to the ConfigureServices method.

What if my language sucks?

Install the following packages to the Persistence Project. The presentation layer is where you would Ideally want to put the Project that the User can Access. To maintain structural Sanity in Mid to Larger Solutions, it is always recommended to follow some kind of architecture.

Its intention is to get rid of transitive dependencies (with explicit focus on dependency from UI to DB). It is doing so by applying the dependency inversion by same principles, described in the ports and adapters. Interfaces are defined in the application core and implemented by the application boundary adapter. Mark Seeman in the “Dependency Injection in .NET”, chapter 2, draw layers without something called “infrastructure”, effectively bypassing this piece of the software as well. He only focusing on analysis of data access as a crucial piece of infrastructure.

What makes Onion Architecture so popular among techies?

Would it be UTC timestamp, or should it be sent with user’s timezone offset? With the offset, set in the global runtime configuration? It totally depends on a logic of the application and on a logic of the web server.

onion architecture

onion architecture solves the problem that we face during the enterprise applications like coupling and separations of concerns. Onion architecture also solves the problem that we confronted in three-tier architecture and N-Layer architecture. In Onion architecture, our layer communicates with each other using interfaces. The Service layer holds interfaces with common operations, such as Add, Save, Edit, and Delete.

What is Onion architecture?

Entities are Domain concepts that have a unique identity in the problem domain. Domain entities encapsulate attributes and entity behaviour. It is supposed to be independent of specific technologies like databases or web APIs. Order is an entity and has attributes like OrderId, Address, UserInfo, OrderItems, PricingInfo and behaviour like AddOrderItems, GetPricingInfo, ValidateOrder, etc. Outer layer data formats should not be used by inner layers.

  • That’s quite everything in this simple yet powerful implementation of Onion Architecture in ASP.NET Core.
  • The presentation layer is where you would Ideally want to put the Project that the User can Access.
  • A Domain Service contains behavior that is not attached to a specific domain model.
  • This will have all the logic related to each Feature / Entity.
  • It also serves as the business logic layer because it contains business logic for an entity.

I have already written a detailed article on MediatR and CQRS patterns in ASP.NET Core 3.1 WebApi Project. You can follow that article and add the Required Commands and Handlers to the Application Layer. These issues were addressed by Onion Architecture, which defined layers from the core to the infrastructure (Separation of Concerns). It follows the fundamental rule by shifting all coupling to the center (Loose Coupling).

Onion Architecture explained — Building maintainable software

We are going to see why this is very useful later on when we get to the Presentation layer. The entities defined in the Domain layer are going to capture the information that is important for describing the problem domain. The Onion architecture is also commonly known as the “Clean architecture” or “Ports and adapters”. These architectural approaches are just variations of the same theme. By doing dependency injection in all the code, everything becomes easier to test.

onion architecture

Onion Architecture is based on the inversion of control principle. Onion Architecture is comprised of multiple concentric layers interfacing each other towards the core that represents the domain. The architecture does not depend on the data layer as in classic multi-tier architectures, but on the actual domain models. The core of an onion architecture comprises several concentric layers that interface with one another. The architecture emphasizes the actual domain models more than the underlying frameworks or technology.

How to Build Microservices Using Onion Architecture: Hands-On Experience

As mentioned earlier, the Core Layers will never depend on any other layer. Therefore what we do is that we create interfaces in the Application Layer and these interfaces get implemented in the external layers. This is also known as DIP or Dependency Inversion Principle. Let’s look at one of the most popular Architecture in ASP.NET Core Applications.