use XML::LibXML;

#Parse XML
my $template = 'xmldocument.xml';
my $parser = XML::LibXML->new();
my $pdoc = $parser->parse_file($template);

#Remember the namespace
my $rdoc = XML::LibXML::XPathContext->new($pdoc->documentElement());
$rdoc->registerNs( ns => 'http://url/Schema' );

#Find desired node(s)
my @stuff = $rdoc->findnodes("//ns:source_name");

#Print results
for(@stuff)
{  my $data = $_->textContent;
   print"$data\n";
}
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