Are there any articles and/or samples of a custom scheme or protocol?
What I mean by scheme or protocol is the first part of an URL, such as
HTTP and FTP. What is necessary to develop a custom protocol in a server?

This is not important. It is something I have been curious about for years.

I assume the details are dependent on the server. Stack Overflow has
questions like c# - Register multiple applications to the same custom
protocol - Stack Overflow
https://stackoverflow.com/questions/62025674/register-multiple-applications-to-the-same-custom-protocol.
They ask about configuring protocols within the client. It is difficult
to find articles about implementing custom protocols in a server.
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