You need to write the handler subroutines. What are you trying to extract from the XML ? Consider using XML::Twig

#!/perl/bin/perl
use strict;
use warnings;
use XML::Parser;

printf "OS %s Perl %s XML::Parser %s\n",$^O,$^V,$XML::Parser::VERSION;

my $parser = new XML::Parser 
   ( Handlers => 
      {   # Creates our parser object
         Start   => \&hdl_start,
         End     => \&hdl_end,
         Char    => \&hdl_char,
         Default => \&hdl_def,
      }
   );

$parser->parsefile('sample_xml.xml');

my $str;
sub hdl_start {
  $str = '';
};
sub hdl_end {
 my ($p, $elt) = @_;
 print "$elt = $str\n" if $elt eq 'parameter';
};
sub hdl_char {
  $str .= $_[1];
};
sub hdl_def {};
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