[XML4Lib] argg, namespaces

[Eric Lease Morgan]

Argg! Namespaces, a necessary evil.

Seriously, how to I write a set of XPath statments to parse an XML  
file that contains a namespace?

I have the following MODS file, and it includes an un-prefixed  
namespace (http://www.loc.gov/mods/v3):

   <?xml version="1.0" encoding="UTF-8"?>
   <modsCollection xmlns:xsi = "http://www.w3.org/2001/XMLSchema- 
instance"
                   xmlns = "http://www.loc.gov/mods/v3"
                   xsi:schemaLocation = "http://www.loc.gov/mods/v3
                   http://www.loc.gov/standards/mods/v3/mods-3-0.xsd">
     <mods version="3.0">
       <titleInfo>
         <title>[Adarna children's book publications]</title>
       </titleInfo>

       <!-- more great mods content here -->

     </mods>
   </modsCollection>

Then, using Perl, I create a LibXML parser, parse the file ($input)  
creating an object, and try to loop through all of the mods elements:

   $parser = XML::LibXML->new;
   $collection = $parser->parse_file( $input );
   foreach my $mods ( $collection->findnodes( '//mods' )) {

     my $titles = '';
     foreach $node ( $mods->findnodes( './/titleInfo/title' )) {
       $titles .= $node->textContent . '|'
     }

     # do more cool stuff here

   }

As written my Perl script never enters the foreach loop, but as soon  
as I remove the namespace declaration from the MODS file the script  
works just fine.

How do I specify the namespace in my findnodes method?

-- 
Eric Morgan