.NET Core Web APIs: Controllers, Middleware, and Authentication

.NET Core Web APIs

A .NET Core Web API is a type of web application built using Microsoft's .NET framework. It allows developers to create RESTful web services that can communicate with other applications, make requests to external websites, perform data processing tasks, and more. In this context, we will delve into three important components of building these types of web apps: Controllers, Middleware, and Authentication.

Controllers

The main component in any web app based on ASP.NET Core MVC (Model View Controller) architecture is the controller. This is where you define your routes and handle incoming HTTP requests. For example, if someone sends a request to http://example.com/api/customers, the ASP.NET Core MVC framework looks up which route maps to that URL and executes its corresponding action method. These actions typically contain logic for working with databases, sending emails, performing calculations, etc., depending on what kind of functionality your API provides.

Middleware

Middlewares are functions that run between the entry point of the server and the final response when an HTTP request comes in from a client. They allow you to modify responses before they are sent back out or validate input coming in, among many other things. There are several kinds of middleware baked right into ASP.NET Core, including the ability to log every request made against your site, set up exception handling, etc.. Additionally, it's possible to implement custom middleware specific to whatever needs your project has.

Authentication

Authentication in ASP.NET Core Web APIs refers to the process of verifying the identity of users who send requests to your website via some form of credentials like username, password, token, etc. One common approach used by Microsoft is OAuth, which involves setting up a callback address within your codebase so that you know how to verify an access token presented by another service. When a user successfully logs into your system after providing their credentials, their browser session gets validated, storing information such as their IP address, device name, and whether they were logged in through SSL SSL stands for Secure Sockets Layer) vs non-SSL traffic.

In summary, understanding the basics of creating controllers, working with middleware, and implementing proper forms of authentication are key aspects of developing robust .Net Core Web APIs capable of serving all manner of dynamic, interactive web pages.