Remember FastCGI? (2021)

Sure, but does anyone remember SCGI?

In my opinion that was step in the right direction, but the protocol design is truly weird. Somehow managing to come up with 4 different ways to encode length of byte strings in otherwise so simple protocol is remarkable achievement.

nginx supports four backend protocols out of the box: HTTP, FastCGI, SCGI, and static files.

Of these, if you get to pick one and the request isn't for a static file, SCGI is the obvious best choice.

You can also load extra plugin modules into nginx itself, of course, including one that puts a Lua interpreter inside nginx (mod_php-style).