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https://github.com/skangas/url-scgi

SCGI support for Emacs using url.el
https://github.com/skangas/url-scgi

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SCGI support for Emacs using url.el

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README 

        
#+TITLE:  url-scgi.el

#+DATE:   2023-01-30

#+AUTHOR: Stefan Kangas 



[[https://elpa.gnu.org/packages/url-scgi.html][https://elpa.gnu.org/packages/url-scgi.svg]]



This library adds support for Simple Common Gateway Interface (SCGI) URLs to the

built-in Emacs ~url~ library.



The SCGI protocol is intended as a replacement for the older CGI protocol, and

is comparable to FastCGI or WAI, but much simpler.  Thus, the SCGI protocol is

most often used by web servers to communicate with a program that serves

dynamically generated pages and files (instead of just static ones).  SCGI is

supported in web servers such as Apache, lighttpd, and nginx.



This library effectively makes Emacs take the place of a web server.  This can

be useful for testing, but not only that.  It was originally developed for

[[https://www.github.com/skangas/mentor][Mentor]], an Emacs front-end for the BitTorrent client ~rtorrent~, where it is

used for remote procedure calls (RPC).



SCGI is described in more detail on [[https://en.wikipedia.org/wiki/Simple_Common_Gateway_Interface][Wikipedia]].  As far as I know, there is no

RFC describing SCGI, nor is there any formal specification.  On the other hand,

the protocol is very simple; it is described in detail [[https://python.ca/scgi/protocol.txt][here]].



SCGI URLs look like this: ~scgi://:~.  See below for an example.



* Installation



url-scgi.el can be installed from [[https://elpa.gnu.org/][GNU ELPA]], an Emacs Lisp package archive that

is enabled by default in Emacs.



Find and install url-sgi.el using this command:



: M-x list-packages



** Usage



First, require ~url-scgi~:



: (require 'url-scgi)



Now, to make an SCGI request with ~url-scgi~, simply call ~url-retrieve~ or

~url-retrieve-synchronously~ with a URL starting with ~scgi://~.



For example, let's assume you have some program listening for SCGI requests on

~localhost~ port ~5000~.  You can then issue a request containing the string

~some-data~ with:



: (url-retrieve-synchronously "scgi://localhost:5000/some-data")



You will want to replace ~some-data~ with something relevant to the program you

are talking to.  Please refer to its documentation for details.



If your application supports XML-RPC (remote procedure calls) over SCGI, you can

make such calls using ~url-scgi~ with the ~xml-rpc~ package.  For example, if

your program supports an XML-RPC method named ~foo~, you would call it like

so:



: (require 'url-scgi)

: (require 'xml-rpc)

: (xml-rpc-method-call "scgi://localhost:5000" "foo")



For more, see the documentation of the ~xml-rpc~ package.



** Contribute



This library is part of [[https://elpa.gnu.org/packages/url-scgi.html][GNU ELPA]] and therefore requires a [[https://www.gnu.org/software/emacs/manual/html_node/emacs/Copyright-Assignment.html][copyright assignment]]

to the [[https://www.fsf.org/][Free Software Foundation]] for any non-trivial contributions.



Please email me a patch, or open a pull request on GitHub, according to your

preferences.



** Contact



You can find the latest version of url-scgi.el here:



https://www.github.com/skangas/url-scgi



Bug reports, comments, and suggestions are welcome!  Email them to Stefan Kangas

 or report them on GitHub.