When perfection isn’t good enough

One of the many possible problems with using CPAN modules is that they often just implement the parts of the problems the author needed a solution for. But once in a while you run into the opposite problem: The module implements parts of a standard that you just don’t want.

Some time ago I had to parse parts of the WebDAV protocol. WebDAV properties are transmitted using XML with namespaces, which is one thing I think XML::Simple is particular bad for. So I turned to XML::LibXML (which is becoming my XML module of choice either way).

So, the WebDAV RFC have examples like this:

     <?xml version="1.0" encoding="utf-8" ?>
     <D:propfind xmlns:D="DAV:">

       <D:prop xmlns:R="http://ns.example.com/boxschema/">
         <R:bigbox/>
         <R:author/>
         <R:DingALing/>
         <R:Random/>
       </D:prop>

     </D:propfind>

Unfortunately XML::LibXML insists on namespace URI’s to conform to the URI specification, which DAV: doesn’t. Due to XML::LibXML’s perfection I’m not able to just use it. Solution:

sub escapeNamespace {
    $_[0] =~ s/(xmlns(?::\w+)?)="(?!urn|http)([^"]+)"/$1="urn:xxx:$2"/g;
    $_[0] =~ s/(xmlns(?::\w+)?)=""/$1="urn:xxx:nonamespace"/g;
}

I’m not quite sure that the second substitution is needed by the standard, but the Litmus webdav test suite needs it…