Re: [GNU ELPA] Proposed new package url-scgi.el

[Stefan Kangas]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>>     https://github.com/skangas/url-scgi
>
> This points to a "specification", but that spec is a bit vague (and
> with some errors) and is not anything like an RFC, so I'm wondering how
> wiedly it's used.  Can you point to actual implementations of SCGI
> clients or SCGI servers to better understand the applicability?

AFAIK, Apache has mod_proxy_scgi[1], and lighttpd has mod_scgi[2]
built-in, and Wikipedia tells me that there is also support in nginx,
Cherokee, and MS-IIS.[3]

I don't know why only the specification exists, and not a proper RFC.
My guess is that it is a combination of SCGI not having enough traction
(with a preference for more fully featured protocols like FastCGI and
WAI) and that it is very lightweight (so cooperation has been easy).

There are, again according to Wikipedia, bindings for a number of
languages, so I would expect there to be more than a handful SCGI
clients out there.  Unfortunately, I had a hard time finding lists of
software that use it.

But I remember that SCGI has been championed within and more popular in
the Python community.  The Python "scgi" module sees frequent updates
(the latest in December 2021), and they helpfully provide a list of
packages that use it (note: "Dependent repositories: 27" and "Used by"):

    https://libraries.io/pypi/scgi

In conclusion, SCGI is not highly popular.  You could maybe even say it
is somewhat obscure.  However, those of us using software that only
support SCGI are, for better or for worse, stuck with it.

Footnotes:
[1]  https://httpd.apache.org/docs/2.4/mod/mod_proxy_scgi.html

[2]  https://redmine.lighttpd.net/projects/1/wiki/Docs_ModSCGI

[3]  https://en.wikipedia.org/wiki/Simple_Common_Gateway_Interface