use strict;
use XML::Rules;

my $parser = XML::Rules->new(
    stripspaces => 7,
    namespaces => {
        'http://www.w3.org/2005/10/markup-validator' => '',
        'http://www.w3.org/2003/05/soap-envelope' => 'env',
    },
    start_rules => {
        warnings => 'skip',
    },
    rules => {
        _default => 'content',
        error => 'as array no content',
        errorlist => 'no content',
        errors => sub { return errors => $_[1]->{errorlist}{error}},
        warning => sub {return warning => $_[1]->{message}},
        'markupvalidationresponse' => 'no content',
        'env:Body' => 'as is',
        'env:Envelope' => sub {return $_[1]->{'env:Body'}{markupvalida
+tionresponse}},
    }
);

my $data = $parser->parse(\*DATA);
use Data::Dumper;

print Dumper($data);

__DATA__
<?xml version="1.0" encoding="UTF-8"?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
...
[download]

XML::Rules lets you tweak and trim the structure produced by parsing the XML so that you end up with only the stuff you need in a format that's most convenient to you.