c# Onion architecture in net core API

Tip #2 – While running the application, you would see that it navigated to ../weatherforecast by default. 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. Next, let’s go to the Infrastructure Folder and add a layer for Database, (EFCore).

  • At the center of Onion Architecture is the domain model, which represents the business and behavior objects.
  • You want isolation between business logic and persistence so that both can perform and grow into their core responsibilities.
  • 4) Infrstructure, actually I don’t think this is a layer, it implements all the above three.
  • As per traditional architecture, the UI layer interacts to business logic, and business logic talks to the data layer, and all the layers are mixed up and depend heavily on each other.
  • Database Independent – Since we have a clean separation of data access, it is quite easy to switch between different database providers.

At SaM Solutions, we’ve developed a kind of platform that allows you to automate the development and deployment of systems that use Docker. Aliaksandr is a Senior .NET developer at SaM Solutions with 13 years of experience. Being a Microsoft certified engineer, he specializes in web development and has experience in creating desktop and mobile solutions. Aliaksandr is fond of learning new technologies, conducting meetups and teaching newbies at internal company courses. For every service, we will write the CRUD operation using our generic repository.

Dependency injection all the way! Easy to test

The Onion architecture is a form of layered architecture and we can visualize these layers as concentric circles. The Onion architecture was first introduced by Jeffrey Palermo, to overcome the issues of the traditional N-layered architecture approach. We’ve chosen MediatR to implement CQRS in the project. Now we need to add the student controller that will interact will our service layer and display the data to the users. In the custom service folder, we will create the custom service class that inherits the ICustomService interface code of the custom service class is given below.

onion layered architecture

Having created a domain model and a web API, we needed to seamlessly connect them. The presentation layer is our final layer that presents the data to the front-end user on every HTTP request. Now in the ICustomServices folder, we will create the ICustomServices Interface, this interface holds the signature of the method.

Result Service

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). This is an opinionated way to set up a Flutter project structure based on service-oriented onion layered OOP app architecture. Over time this will be a collection of about 15 articles on Flutter project set up.

Basically, it highlights the usage of inversion of control once again. You already have seen this when we were discussing ports and adapters. You can add as many layers as you need at any level you want. So if you want to define a layer for Domain services you can. The separation not necessarily has to be physical with projects, but can be just logical with folders.

Application Structure & Layers

This allows us to configure our services inside of the Startup class. Onion architecture consists of several concentric layers interacting with each other towards the core, which is the domain. The architecture does not depend on the data layer, as in a traditional three-tier architecture; it depends on real domain models. The popularity of microservices is growing due to the range of benefits they offer to developers and businesses. In this article, I will tell you about my experience of using onion architecture with a harmonized combination of DDD, ASP.NET Core Web API and CQRS for building microservices.

onion layered architecture

Even though, those rules are pretty agile, in practice, 3 layers were more than enough for most of the projects. He published “Patterns of Enterprise Application Architecture” where N-layered architecture was described. You also don’t need to have experience with all of them. In other aspects, I took the risk that most both beginning and novice Flutter devs will recognize that repositories refers to service layers. I hope that presence of CoreUtils in the solution helps you to avoid an excessive interfaces creation.

Unfolding infrastructure in the Onion architecture

The drawback of this traditional architecture is unnecessary coupling. The Onion Architecture relies heavily on the Dependency Inversion principle. So tools like Guice, Ninject etc. are very helpful for those kinds of architectures but not a necessity. The presentation layer entry point is the LayerProductionPresenter. The LayerProductionPresenter uses the ILayerProductionApplicationService to open a factory and produces layers by using the previously opened factory.

The presentation Layer usually holds the Part that the User can interact with, i.e, WebApi, MVC, Webforms, and so on. Business Logic is probably the most important part of this entire setup. It holds all the logic related to the Business requirements. Now, every application ideally has its own dedicated Database.

My Expert Project SetUp, Layered Onion Architecture

That implementation would be in higher layers, like the domain service layer. Onion architecture is built on a domain model in which layers are connected through interfaces. The idea is to keep external dependencies as far outward as possible where domain entities and business rules form the core part of the architecture. We simply move all infrastructure and data access concerns to the external of the application and not into the center.

onion layered architecture

Here we will just Add Mediator to the service collection. We will implement the Mediator pattern later in this tutorial. We will have to register Swager within the application service container. Navigate to ../Startup.cs and add these lines to the onion layered architecture ConfigureServices method. Domain and Application Layer will be at the center of the design. To clearly understand the advantages of Onion Architecture in ASP.NET Core Applications, we will need to study the issues with N Layer Architecture.

Struct vs. Record vs. Class in C#

The outer layer is reserved for things that change often outside of the applications core business logic that interact with it. In the case of the UI, it is a service in itself, it will have its own logic and tests which validate it behaves as expected. If you are looking to test the entire system then that would be an end-to-end test that would be performed.


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