Add IHttpHandler to Blazor project

Question

In order to be able to serve audio from a SqlServer database in a Blazor project I need to have an IHttpHandler in the project. I could add an AudioHandler.ashx and AudioHandler.ashx.cs file to the project, but what else (NuGet package for instance) do I need to add in order to be able to use the IHttpHandler interface like:

public class AudioHandler : IHttpHandler
{
}

And how can I register this handler so it can be called from Javascript?

Thanks a lot in advance!