This post is about running background tasks in ASP.NET Core. In .NET Core 2.1, Microsoft introduced a new feature called IHostedService to allow developers to run a background service that can have a managed lifetime to its caller, be it from an ASP.NET Core or a console.
To enable Background processing, you need to create a class which implements IHostedService interface.
This interface got two methods StartAsync and StopAsync. And you need to register the service using dependency injection, like this.
Finally you can consume it in the controller like this.
Instead of implementing IHostedService, you can derive from Background abstract class and you can implement the ExecuteAsync abstract method. Here is an example of a minimal background service, which monitors a table in SQL Server and send emails.
In this example, the background service monitor the check the table in every 5 minutes and if records found, send the email using SendEmailAsync method.
Keep in mind that these services running on your application context, if the service is consuming memory or CPU it is not recommended. There are Azure Web Jobs and Azure Functions which helps you to handle dedicated background jobs.