Create a new endpoint in an ASP.NET Core

To create a new endpoint in an ASP.NET Core application, look at the code:

app.UseEndpoints(endpoints =>
{
    endpoints.MapGet("/", async context =>
    {
        await context.Response.WriteAsync("Hello World!");
    });
});

In this code:

• app.UseEndpoints is used to define the endpoints for the application within the endpoint routing middleware.
• endpoints.MapGet("/", ...) maps an HTTP GET request to the root URL ("/") of the application.
• When a GET request is made to the root URL, the lambda function inside MapGet will execute, sending "Hello World!" as the response. This effectively creates a new endpoint in the app at the "/" route.

An endpoint has execution logic apart from URL and HTTP verb.

in ASP.NET Core, an endpoint can contain more than just a URL and an HTTP verb; it can also include execution logic and additional metadata.

Here’s a breakdown of what an endpoint in ASP.NET Core can include:

1. URL (Route Template): The path pattern or template, such as "/" or "/api/products/{id}", that the endpoint responds to.
2. HTTP Verb: The specific HTTP method (e.g., GET, POST, PUT, DELETE) that the endpoint should respond to. For example, MapGet restricts the endpoint to only respond to GET requests.
3. Execution Logic: The core of an endpoint is often a delegate or function that contains the actual logic to be executed when the endpoint is called. In your example:
• async context => { await context.Response.WriteAsync("Hello World!"); }
• This function defines what the endpoint does upon receiving a request (in this case, it sends "Hello World!" as the response).
4. Middleware Pipeline (Filters): You can configure middleware that applies only to specific endpoints. This can include authorization, authentication, or other custom filters that affect how the endpoint handles requests.
5. Metadata: Endpoints can include metadata, such as route parameters, custom attributes, and additional data (e.g., [Authorize], [Produces("application/json")]). This metadata can be used by middleware and tools to process the request or control access.

Endpoints in ASP.NET Core are, therefore, more than just mappings of URLs to HTTP methods; they encapsulate all the components needed for processing requests, making them very flexible for building web APIs.