Comment by mananaysiempre

You might also want to look into ISAPI extensions[1,2] in Microsoft’s IIS, those are also just DLLs that the web server loads into itself, and were once advertised as the most performant way to serve dynamic stuff from it. It doesn’t look like there’s a way to request that extensions be reloaded, though: the server either unloads them at its discretion (once no in-flight requests are using them?) or not at all (if “extension caching” is enabled). But there’s an advert[3] from somebody who shimmed that capability onto it back in 2006.

(You wouldn’t have had a good day debugging these things, mind you. But it’s something that people experimented with back in the day, alongside Web servers programmable in Java[4] or Tcl[5].)

[1] https://learn.microsoft.com/en-us/previous-versions/iis/6.0-...

[2] http://library.thedatadungeon.com/msdn-1998-06/IISRef/devdoc...

[3] https://www.iis.net/downloads/community/2006/12/isapi-loader

[4] https://www.w3.org/Jigsaw/Overview.html

[5] https://wiki.tcl-lang.org/page/AOLserver