From: Dennis Newbold <dennisn@...>
Date: 2002-03-16T13:27:29+09:00
Subject: Re: (sort of)OT: CGI, FastCGI, etc.

Hi Albert,

    I'm not a total expert myself, but --

  1. the short answer to your question is -- probably not much.
     A CGI script is something that you write, and which runs on a
     machine running a web server, such as Apache.  As a small
     example, suppose you go to a website where they want you to fill
     out a form with some information about yourself.  After you do
     this, you click on a button that probably says "SUBMIT" or something
     like that.  The web browser program grabs all the stuff you typed
     in, and sends it over to the web server, which starts up a
     thread to execute a CGI script program, and gives all the data
     that the web browser sent to it to your CGI script program.
     Your CGI program can then do whatever it wants with the data:

         analyze it for errors, and send an error message back
         to the web browser, or

         spell check it, or

         write all the data into a record in a data base, or

         use the data to select some information from a database
         and send it back to the web browser or

        use your imagination.

    As you can see, the possibilities of CGI make it very attractive
    (especially when coupled with other stuff like PHP3, JavaScript,
     etc.).  Which means that at any given point in time, a popular
    webserver is being asked to run 50 - 100 or more CGI scripts.
    That increases the load on the server, making it slower to respond
    to incoming requests.  When those incoming requests are likely
    to generate money for the owner of the web server, this translates
    into lost revenues.  This is where FastCGI comes in.  FastCGI
    is basically a way to minimize the server load, so that it can
    handle requests more quickly.  It is often implemented as a module
    that a webserver, such as Apache, can use.  It works (I believe) by
    keeping the threads, code, and maybe some data, for frequently used
    CGI scripts in memory, which means that when the web server needs
    to run it, it doesn't have to start up a new thread or process, and
    run the code in from disk every time.

    There's some basic info about CGI scripting at the NCSA website
    (I believe, its been awhile since I looked at it), but your best
    bet is to start with a good book.  Try a computer bookstore, or
    www.amazon.com, www.oreilly.com, www.fatbrain.com, www.opamp.com.

    Good luck.

Dennis

On Sat, 16 Mar 2002, Albert Wagner wrote:

> I'm a total web newbie.  I'm learning HTML and trying to understand how CGI 
> works.  What relationship is there, if any, between the Ruby CGI class and 
> the FastCGI ruby module?  How might I best start this steep climb?  Books? 
> Docs?  Links?
> -- 
> Quantum Mechanics: The dreams stuff is made of
>