Cannot receive callback after calling RegisterServiceCtrlHandlerEx() in Microsoft.Extensions.Hosting.BackgroundService

Question

I followed links to implement a Windows service in .NET and ASP NET.

https://learn.microsoft.com/en-us/dotnet/core/extensions/windows-service
https://learn.microsoft.com/en-us/aspnet/core/fundamentals/host/hosted-services?view=aspnetcore-6.0&tabs=visual-studio

Now I want to handle Power events and follow the link to call RegisterServiceCtrlHandlerEx() in my BackgroundService construct method.
https://learn.microsoft.com/en-us/windows/win32/power/registering-for-power-events

The call to RegisterServiceCtrlHandlerEx succeeds, but there is no any callback when I change some Power settings.

Any idea why it is not working?

Thanks.

Answer 1

you used the cross platform template and it does not support service events. You need to create a new console project (there is no template) and use ServiceBase to create the service callback.

https://learn.microsoft.com/en-us/dotnet/api/system.serviceprocess.servicebase?view=dotnet-plat-ext-6.0

Example

https://dotnetcoretutorials.com/2019/09/19/creating-windows-services-in-net-core-part-1-the-microsoft-way/

Typically when creating a service, you run the actual service code on a separate thread, you can also write as async. For example the onStop callback needs to be able to stop the service processing code, you can use a cancellation token for this.

Depending on you needs, you may also need to implement a ServiceProcessInstaller

https://learn.microsoft.com/en-us/dotnet/api/system.serviceprocess.serviceprocessinstaller?view=netframework-4.8&viewFallbackFrom=dotnet-plat-ext-6.0

Note: I’ve only written services in C/C++, but the above libraries look like thin wrappers around the o/s code.