AJAX.

• search.cpan.org/perldoc?CGI::Ajax
• AJAX and Perl-based web applications
• http://www.perl.com/pub/a/2006/03/02/ajax_and_perl.html
• http://perl.about.com/b/2006/03/17/using-ajax-from-perl.htm

...among others.

Update: Fixed 3rd link; thanks Corion & planetscape. Added the fourth.

Ya, I think this AJAX stuff is cool, but I'm already having a time trying to get it to work with XAMPP. When I put the .pm module on the path, i get some constructor function error at runtime.

You can use the chunked transfer encoding to write sequentially to the client. Browsers (usually) parse and display the sent data immediately after the first chunk is read.

Update: mod_perl example

package My::Stream;

use strict;
use warnings;
  
use Apache2::RequestRec ();
use Apache2::RequestIO ();
use Apache2::Const -compile => qw( OK );

sub handler :method {

    my $invocant       = shift;
    my $request_record = shift;

    $request_record->content_type( 'text/html' );

    for ( 1 .. 10 ) {
        $request_record->print( "<p>$_</p>" );
        $request_record->rflush;
        sleep 1;
    }

    return Apache2::Const::OK;

}

1;
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Tatsumaki is a framework written specifically for streaming content, non-blocking would help you with your continuous writing, aka streaming.

#!/usr/bin/perl

use strict;
use warnings;
use CGI::ProgressBar qw/:standard/;

$|=1;

my $cgi = new CGI;
                       
print header, 
        start_html( 
                   -title =>'Example of ProgressBar', 
                   -style=>{ -src => ' ', 
                             -code => ' ', 
                   }
                   
        ), 
        h1('A Simple Example'), 
        p('This example will update a JS/CSS text progress bar.'), 
           progress_bar( -from=> 1, -to=> 100 ); 

for (1..10){ print update_progress_bar; 
      sleep 1; 
} 

print hide_progress_bar; 
print p('All done.'); 
print end_html;
exit(0);
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