ASP.NET Core Fundamentals (Part 2)

In Chapter 3, we learned about three important components in ASP.NET Core: routing, configuration, and environment. Next, let’s continue to explore the other components in ASP.NET Core.

In this chapter, we will cover the following topics:

• Logging
• Middleware

ASP.NET Core provides a flexible logging API that works with many logging providers. We can send and store the logs in various destinations, such as the console, text files, Azure Application Insights, and so on. When the application has issues, logs can help us find out what is going on. Logging belongs to a bigger topic called observability, which is a set of practices that help us understand the state of the application. In this chapter, we will learn how to use the logging API in ASP.NET Core.

Middleware is a component that can be plugged into the request pipeline to handle requests and responses. It is one of the most important improvements in ASP.NET Core compared...

Technical requirements

The code examples in this chapter can be found at https://github.com/PacktPublishing/Web-API-Development-with-ASP.NET-Core-8/tree/main/samples/chapter4. You can use VS 2022 or VS Code to open the solutions.

Logging

Logging is an important part of any application. A well-designed logging system can capture data that helps you diagnose problems and monitor the application in production. Logging gives you insight into how, when, where, and why significant system events occurred so that you know how the application is performing and how users are interacting with it. Logging may help you to identify security weaknesses or potential attacks. Logging can also help you audit users activities.

Logging should not impact the performance of the application. It should be fast and efficient. It should not affect any logic of the application. When you add logging to an application, you should consider the following points:

• What information should be logged?
• What format should log messages be in?
• Where should log messages be sent?
• How long should log messages be kept?
• How to make sure log messages won’t impact the performance of the application?

In this section...

Middleware

In this section, we will introduce middleware, which is one of the most important improvements in ASP.NET Core.

To follow this section, you can run the following command to create a new ASP.NET Core web API project:

dotnet new webapi -n MiddlewareDemo -controllers

You can download the example project named MiddlewareDemo from the chapter’s GitHub repository.

What is middleware?

ASP.NET Core is a middleware-based framework. An ASP.NET Core application is built upon a set of middleware components. Middleware is a software component that is responsible for handling requests and responses. Multiple middleware components form a pipeline to process requests and generate responses. In this pipeline, each middleware component can perform a specific task, such as authentication, authorization, logging, and so on. Then, it passes the request to the next middleware component in the pipeline. It is a huge improvement over the traditional ASP.NET framework, which...

Summary

In this chapter, we learned about the logging framework in ASP.NET Core, and introduced a third-party logging framework, Serilog, to help us write logs to different sinks, such as files, console, and Seq, which is a tool that analyzes logs using structured logging. We also learned what middleware is, how to use the built-in middleware components, and how to create a custom middleware component.

It is time to implement some real business logic in the next chapter. We will introduce Entity Framework Core (EF Core), a powerful object-relational mapper (ORM) framework, to help us access the database.