use XML::Simple;

undef $/;
$data = <DATA>;

$ref = XMLin($data);

print "Volume: " . $ref->{'volume'} . "\n";
print "Issue: " . $ref->{'issue'} . "\n";
print "Year: " . $ref->{'year'} . "\n";

__DATA__
<data>
<volume>4</volume>
<issue>12</issue>
<year>2003</year>
</data>