ASP.NET Core architecture overview

To follow the next chapters, you should be familiar with the base architecture of ASP.NET Core and its components. This book tackles almost all of the components of the architecture.

The next figure shows the base architecture overview of ASP.NET Core 5.0. Let’s quickly go through the components shown here from the bottom to the top layer:

On the bottom, there is the Hosting layer. This is the layer that bootstraps the web server and all the stuff that is needed to start up an ASP.NET Core application, including logging, configuration, and the service provider. This layer creates the actual request objects and their dependencies that are used in the layers above.

The next layer above Hosting is the Middleware layer. This one works with the request object or manipulates it. This attaches the middleware to the request object. It executes the middleware for things such as error handling, authenticating HSTS, CORS, and so on.

Above that, there is the Routing layer, which routes the request to the endpoints depending on the route patterns defined. Endpoint routing is the new player from ASP.NET Core 3.1, and separates routing from the UI layers above to enable routing for different endpoints including Blazor, gRPC, and SignalR. As a reminder: in previous versions of ASP.NET Core, routing was part of the MVC layer, and every other UI layer needed to implement its own routing.

The actual endpoints are provided by the fourth layer, the UI layer, which contains the well-known UI frameworks Blazor, gRPC, SignalR, and MVC. This is where you will do the most of your work as an ASP.NET Core developer.

Lastly, above MVC, you will find WebAPI and Razor Pages.