my $rdfns = "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
my $writer = new XML::Writer(OUTPUT => \$output, NAMESPACES => 1);
$writer->startTag([$rdfns, "Description"]);
$writer->startTag("greeting",
                  "class" => "simple");
$writer->characters("Hello, world!");
$writer->endTag("greeting");
$writer->endTag("Description");
$writer->end();
print $output;