Perl script implementing "Comma tools" that can be chained. Originally http://lists.w3.org/Archives/Public/public-qa-dev/2004May/0023.html

commatools.pl

#!perl -w
use strict;
use warnings;
use URI::Escape 'uri_escape';

sub tool
{
  my $req = shift;
  return unless defined $req;

  my ($new, $tool, $param) = $req =~ /^(.*),(\w+)(?:=(.+?))?$/;
  return unless defined $tool;

  my %tools = map { split/\s+/ } <DATA> ;
  my $dst = $tools{$tool};
  return unless defined $dst;

  my $host = $ENV{HTTP_HOST} || $ENV{SERVER_NAME};
  return unless defined $host;
  $host =~ s/:\d+$//;

  $new = uri_escape("http://$host$new", "^A-Za-z0-9\-_.!~*'()");
  $param = uri_escape($param, "^A-Za-z0-9\-_.!~*'()");

  $dst =~ s:\$uri:$new:;
  $dst =~ s:\$param:$param: if defined $param;

  return $dst;
}

my $tool = tool $ENV{REQUEST_URI} ;
if (not defined $tool)
{
  print "Status: 404\n\n";
}
else
{
  print "Status: 302\n";
  print "Location: $tool\n\n";
}

__DATA__
links   http://www.google.com/search?q=link:$uri
text    http://cgi.w3.org/cgi-bin/html2txt?url=$uri
xslt    http://w3.org/2000/06/webdata/xslt?xslfile=$param&xmlfile=$uri
...