use strict;
use warnings;

use IO::Scalar;
use XML::Writer;

my $writer = XML::Writer->new(
    OUTPUT => IO::Scalar->new()
);

$writer->startTag("greeting", "class" => "simple");
$writer->characters("Hello, world!");
$writer->endTag("greeting");
$writer->end();

my $output = $writer->getOutput();

# optionally run $output through a filter

print $output;