Understanding Onion Structure: An Example Folder Construction By Alessandro Traversi

We have already mentioned the advantages and challenges this architecture has addressed. These have turn out to be the reasons onion architecture has turn out to be so well-liked among the many techies. The application is separated into layers, every with its personal duties and issues.

To learn how to implement the repository sample with Entity Framework Core you probably can try this text ASP.NET Core Web API – Repository Pattern. This means that when a better layer references the Services.Abstractions project it will solely have the flexibility to call strategies which would possibly be exposed by this project. We are going to see why this is very useful in a while once we get to the Presentation layer. With this approach, we are being very explicit about what the higher layers of the Onion can and can not do.

Developing a system core that’s both secure and efficient is essential when basing a system’s architecture on that of an onion. Emphasizing the separation of issues and dependencies on this layered fashion, will increase the number of maintainable applications operating simultaneously. If onion-based architecture is set up properly, it is intended to supply insurance against the evolution of know-how that may make merchandise out of date not long after they’re developed. The domain model is on the center of Domain-Driven Design or improvement, which totally understands a domain’s procedures and regulations. It creates software for classy necessities by carefully connecting the implementation to a altering mannequin of basic business ideas. The major difference between “the classic” three-tier structure


The Domain project will maintain the Domain layer implementation. The Services and Services.Abstractions are going to be our Service layer implementation. The Persistence project shall be our Infrastructure layer, and the Presentation project will be the Presentation layer implementation.

  • And the most difficult task was to find a steadiness between all these features.
  • C# programmers are drawn to Onion Architecture due to the dependency flows.
  • Onion structure can be applicable to microservices when viewing every microservice in isolation.
  • Technology lovers today use Model-View-Controller structure as a most well-liked internet utility structure.
  • During my Engineering career, I’ve worked on a quantity of projects utilizing totally different architectural kinds.

Then we saw how the Service layer was created, where we’re encapsulating our business logic. We have connected all of our Onion structure implementation layers, and our application is now prepared to be used. By now it must be apparent that the Presentation project will solely have a reference to the Services.Abstraction project. And since the Services.Abstractions project does not reference some other project, we have imposed a very strict set of strategies that we can name within our controllers. Now we only have yet one more layer left to complete our Onion structure implementation. The primary thought behind the Onion architecture is the flow of dependencies, or quite how the layers work together with one another.

Onion Structure: The Professionals And Cons Of Onion Improvement

C# programmers are drawn to Onion Architecture as a result of dependency flows. If you are interested in learning extra C# while working with the Onion Architecture, go to the TechRepublic Academy. This layer, the outermost layer of Onion, is a spot where all framework and technology related stuff goes. It tends to be essentially the most “thick” since it incorporates the implementations of the interfaces defined within the inside layers.

onion structure

in style Hexagonal / Ports and Adapters structure, and as such is predominantly used within the backend, enterprise applications and companies. During my Engineering career, I’ve labored on a quantity of tasks utilizing totally different architectural kinds.

technical-oriented services, e.g. a high-throughput proxy written in a reactive framework. It allows builders to easily change or replace any layer without affecting the opposite layers. It also enables automated testing at each layer, which makes it simpler to make sure the correctness and quality of the applying. Overall, the Onion Architecture is a versatile and scalable architecture that can be adapted to various sorts of purposes and applied sciences. Onion structure may appear onerous in starting but is extensively accepted in the industry.

Hexagonal Architecture For Backend Functions

Dive into the core ideas of software program growth that stand robust amidst the rise of Generative AI. Learn how clear necessities, human collaboration, and agile strategies form success in tech. Low coupling happens when one module interacts with another with out worrying about the internals of the other module. The inner implementation of exterior layers does not need to be a priority for all internal levels. As talked about above initially of the article, Onion Architecture isn’t a one-size-fits-all resolution.

Again, the whole process is nicely described in our Ultimate ASP.NET Core Web API book. Also, because you reference a service layer in the principle project and if you use mappings within the service layer as well, then install it in the service layer. But, I assume, you shouldn’t be doing any mappings inside the Presentation layer (controllers). Keep all of the mappings in the service layer and return the required outcomes to your controllers.

onion structure

The deeper the layer resides contained in the Onion, the fewer dependencies it has. Testability is very excessive with the Onion architecture because every little thing depends on abstractions. The abstractions may be easily mocked with a mocking library such as Moq.

On the other facet though, having the compiler on your facet could be very helpful onion architecture, and prevents the above-mentioned issue. The path of the dependencies between layers is

Separation Of Issues:

Many wish to change and continually enhance but I at all times say just because you possibly can change something doesn’t imply you should. This is not at you OP this is extra on the dev community as a complete. Once once more thanks for the refresher and reflection on onion structure. Just, you don’t have these ConfigureServiecs and Configure strategies, but a builder object that you simply use to access the Services assortment or to register a middleware inside the pipeline. Our Web API guide is completely updated with .NET 7, using Onion Architecture, with the SQL database, so you would possibly give it a glance, it will help you for positive. The downside I’m facing is there could be I even have lots of additional validation that usually requires calling a service.

Yes, it could be partial lessons however basically, these classes are just simple wrappers around individual repos/services. We started with the Domain layer, where we noticed the definitions for our entities and repository interfaces and exceptions. This line of code will find the entire controllers inside the Presentation project and configure them with the framework. They are going to be handled the identical https://www.globalcloudteam.com/ as if they were outlined conventionally. We are using a Web API constructed with ASP.NET Core to create a set of RESTful API endpoints for modifying the area entities and allowing customers to get again the information. However, within the OnModelCreating technique, we’re configuring our database context primarily based on the entity configurations from the identical meeting.

The domain, though the most important a half of the application, tends to be additionally the smallest in terms of code measurement. An utility written to assist handle a Library would most probably have courses like Book, Reader, Copy and so forth.

The Clean Code

At times, we needed to move a specific functionality into a separate microservice if it appeared in many locations within the system. On the contrary, if some functionalities were tightly connected, we needed to combine microservices into one. And probably the most challenging task was to discover a stability between all these functions. Our buyer wanted a software system suitable with their hardware so that shoppers might purchase gear, set up software and create and handle content material. The challenge was to create a cloud software program solution for a digital signage hardware producer. If you’ve comparatively fastened queries that won’t change easily, this architecture would work very well.