From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-09-08T05:25:28+09:00
Subject: [ANN] acgi-0.0.0

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URIS

   http://codeforpeople.com/lib/ruby/acgi/


SYNOPSIS

   as=C2=B7sid=C2=B7u=C2=B7ous (adj.)

     1. constant in application or attention; diligent: an assiduous worker=
 who
     strove for perfection.

     2. unceasing; persistent: assiduous research.

   acgi : assiduous or ara's cgi (emphasis on the 'ass' in assiduous) a dro=
p-in
   replacement for ruby's built-in cgi that provides copious features such =
as

     - persistence
     - speed
     - simplicity
     - familiarity
     - no apache modules
     - browser neutrality
     - could easily be made platform independent
     - ability to install via ftp
     - no special webserver setup or privledges required
     - session affinity (no process pool) so mem caching is simple
     - 91 lines of ruby code

ARCHITECHTURE

   the design of acgi is similar to that of fastcgi (http://www.fastcgi.com=
) but
   requires no external modules, configuration of apache, etc.

   a acgi application consists of a cgi server backend which loops, handlin=
g all
   incoming requests; the requests are delegated to this backend server via=
 a
   simple, fast to start up, 'index.cgi' program written in c.  communicati=
on
   between 'index.cgi' and it's backend server is via named pipes (fifos):


                         -------------
                         | index.cgi |          <- transient (compiled c co=
de)
                         -------------
                         |=09|   |
                         | fifos for stderr, stdout, stdin, env
                         |=09|   |
                        /=09|    \
                 ------------------------------
                 |                            |
                 |         cgi server         | <- persistent (looping ruby=
 code)
                 |                            |
                 ------------------------------

   note that the architechture is similar in spirit to fastcgi - it provide=
s
   speed by avoiding startup overhead and redundant work like database conn=
ection
   setup.  in this case, contrasted with fastcgi, the whole thing takes pla=
ce
   outside of the webserver in the application domain.

REQUEST CYCLE

   - request comes in to web server

   - request is passed to index.cgi, a very simple compiled c program which=
 in
     turn does the following

       - make sure the ruby server is running, spawn it in the background i=
ff
         required.  this is a non-blocking operation that functions as a si=
mple
         process manager to ensure a server is running at all times.

       - aqurire a lock to prevent other invocations of index.cgi from
         overlapping - all invocations procede one at a time in the order o=
f
         receipt.  there are never concurrent requests to the server.

       - serialize the environment and send it down a fifo

       - read any stderr/stdout from the ruby server via fifos and write th=
em to
         stderr/stdout respectively

       - release lock

   - the ruby server, for it's part, does the following

     - aquire a lock which prevent multiple copies from running simoultaneo=
usly.
       this is the same lock the c program checks.

     - loops

       - loading the environment

       - handling request with stderr/stdout/stdin redirected

   the cycle is mostly transparent to the cgi progam.  to convert an existi=
ng cgi
   program to an acgi program one would simply change

     require 'cgi

     cgi =3D CGI::new
     establish_database_connection
     generate_content

   to

     require 'acgi

     establish_database_connection

     ACGI::each_cgi do |cgi|
       generate_content
     end


IMPLEMENTATION

   shoddy.

   this version is proof of concept only!!!  it's likely to run only on lin=
ux,
   though it may run on many *nix platforms.  or maybe not.  there is littl=
e to
   no error checking, the sun could explode if you run the example program.
   security is not considered.


RUNNING THE EXAMPLE

     - unpack tarball in webroot
     - make
     - point browser at http:://your.host.com/path/where/you/unpacked/index=
=2Ecgi

   obviously you'll need cgi setup for you web server, ruby installed, etc.

     - try changing server.rb and running 'make restart'


BUGS

   > 42


WHY?

   i think the idea is neat enough to pursue.  i'd like to get a minimal pa=
ckage
   going that supported windows and *nix.  if you are interested in partici=
pating
   please contact me.  mostly i'm in need of windows c/ipc knowledge.

EMAIL

   ara [dot] t [dot] howard [at] noaa [dot] gov

-a
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| email :: ara [dot] t [dot] howard [at] noaa [dot] gov
| phone :: 303.497.6469
| Your life dwells amoung the causes of death
| Like a lamp standing in a strong breeze.  --Nagarjuna
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