use strict;
use warnings;
use XML::Writer;

my $outputStr;

open my $output, '>', \$outputStr;

my $writer = new XML::Writer(OUTPUT => $output);

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

print $outputStr;