Run a .exe to create a HTML page

I have seen something interesting a few months ago. The Deutsche Bahn has a page to order tickets and in the URL (https://reiseauskunft.bahn.de/bin/query.exe/) I found "query.exe".

So here are my questions:
1) How can I run a .exe on my server to return a webpage? Do I have to write the page into the console?
2) And maybe more advanced: how do I get the GET and POST parameters?
3) And can I build it with .NET Core to run it on Linux?

I tried to simply drag and drop the path to my exe in my browser but all I achieved was a download file dialog.

I hope you can help me :)