CGI and PHP Review

CGI Programming

Draw a simple picture of a web client, web server, and show that the cgi program runs on the web server.

When client uses URL which specifies a cgi program, the web server recognizes that it is a cgi program based off of its extension .cgi or .php3. Instead of displaying the file it runs the program and displays the programs output. The output of the program should be htmlized.

What languages can we use to make a cgi program?

• almost any
• we used PHP because it is growing more popular, it is based on Perl and C/C++

GET vs. POST

The GET method will put the parameter list (eg. var1=3&var2=hello) into an environment variable which usually has an 80-255 character limit. The POST method sends the parameter list to the program through the standard input stream.

Passing parameters through a URL

Uses the GET method.

    http://your.server/test.php3?var1=Hello&var2=5

Passing parameters through an HTML Form

Specify which method to use in the FORM tag.

    < FORM ACTION="test.php3" METHOD="POST" >
    < INPUT TYPE=text NAME=var >
    < INPUT TYPE=submit >
    < /FORM>

PHP

• comment characters: #, //, or /* */
• variable names are case sensitive and all start with $
• don't have to declare variables
• function names are not case sensitive
• print is most common function used in cgi scripts
• cgi parameter names can be accessed through variable with same name with a $ in front

<?php_track_vars?>
<?
        print "Values submitted via POST method:<br>";


        /* reset() rewinds the given array's internal ptr to first elem */
        reset($HTTP_POST_VARS);

        /* list() - isn't really a function, assigns a list of
           vars in one operation, in this case each returns a
           key, value pair which list is assigning to $key and
           $val */
        while (list ($key, $val) = each ($HTTP_POST_VARS)) {
                print "$key => $val<br>";
        }
?>

Related Web Sites

• Basic CGI
• PHP Home page