Example 1: A simple HTML form and a CGI program in Moscow ML
------------------------------------------------------------

An HTML form has an associated action, which is usually a call to a
CGI program, such as 
	ACTION="http://www.dina.kvl.dk/cgi-bin/sestoft/cgiex1"

When the user submits the form, the webbrowser will send a request to
the indicated webserver (www.dina.kvl.dk).  The server will invoke the
CGI program WWWSERVERPREFIX/cgi-bin/sestoft/cgiex1 to handle the
request (the WWWSERVERPREFIX is an installation-specific path;
typically /var/lib/httpd).


To send a form from the client (browser) to a WWW server, and make the
server respond properly, you need to write the following components:

	(A) An HTML page containing a FORM
	(B) A CGI program to receive the form, process it, and respond
  
(A) You need an HTML page containing a FORM.  The FORM must have

	- METHOD="POST" 
	- an ACTION equalling the URL of a CGI program
	- any number of named INPUT, SELECT, or TEXTAREA fields
	- one or more INPUT fields with TYPE=SUBMIT

See file `htmlform.html' for an example HTML form.  With that form,
you can type in a text in a TEXTAREA (on the system running the
browser) and choose whether you want to count the number of characters
in the textarea, count the number of lines in the textarea, or sort
the lines of the textarea.

Note that in htmlform.html, the textarea is named "texttoprocess" and
the select menu is named "action".

(B) You need a CGI program

See file `cgiex1.sml' for an example CGI program.  That program will
handle requests sent from the above-mentioned example form.  Within
the example CGI program, the contents of the HTML form's textarea is
retrieved as
	Mosmlcgi.cgi_field_string "texttoprocess"
and the chosen select menu option is retrieved as
	Mosmlcgi.cgi_field_string "action"


INSTRUCTIONS FOR USE

(1) Edit the FORM in file `htmlform.html' so that ACTION refers to a
cgi-bin directory on your local webserver.

(2) Compile the CGI program:

   mosmlc -c cgiex1.sml
   mosmlc -o cgiex1 cgiex1.uo

(3) Install the compiled CGI program on your local webserver:

   cat `which camlrunm` cgiex1 > /var/lib/httpd/cgi-bin/sestoft/cgiex1
   chmod a+x /var/lib/httpd/cgi-bin/sestoft/cgiex1

The above assumes that your webserver lives in /var/lib/httpd/ so that
your CGI program directory is /var/lib/httpd/cgi-bin/sestoft/, and
that you are allowed to install CGI programs on your webserver.
Change the path as appropriate.  (Note that the runtime system is
simply prepended to the ML bytecode, so that the webserver need not
look for it.)

The included Makefile automates steps (2) and (3) above.

(4) Open the HTML file `htmlform.html' with your webbrowser, fill in
the form, and click on `Send'.