#!/usr/bin/perl
#

use strict;
use CGI ':standard';
use CGI::Carp qw(fatalsToBrowser set_message);
use Data::Dumper;
# other modules

# error handler
BEGIN {
  sub handle_errors {
    my $msg = shift;
    print "<h1>Script Error</h1> running".$ENV{'SCRIPT_NAME'}."<p><pre>";
    $msg =~ s/ (of )*\Q$0//g;
    print "$msg</pre><A HREF='/'>Email me this page</a>";
    }
  set_message(\&handle_errors);
}

# main program starts here

my $debug = 1;
my $cgi = new CGI;

#put authentication here if required

my $phase = identify_phase() 
# $phase = 0 if just printing form otherwise 1 (for complex transactions may return 2, 3 etc.)
print_form() unless ($phase); # this routine probably does not return
my $validref = validate_params()
print $cgi->header, $cgi->pre(Dumper($validref)) if ($debug);
# list example Dumper($validref) output to show what is OK
unless ($validref{error}) {
  execute($phase, $validref );
}
else {
  report_param_errors( $validref );
}
exit;
# subroutines

# phase 0 if no posted paramters etc etc
sub identify_phase() {
}

sub print_form() {
}
sub validate_params() {
}
sub report_param_errors( ) {
  my ($parmref) = @_;
}
sub execute() {
  my ($phase, $parmref) = @_;
}