Thanks for the thorough reply!

I used SOAP::Data -> name(identifier => $identifier ) -> type('xsd:long'); and obliterated the type error.

Unfortunately, now it seems I'm getting another error from SOAP::Lite when the returned XML is too long... I am stuck with SOAP since that is the only way for me to retrieve the data I want. I'll check out the other SOAP modules that you proposed, maybe they will better handle large amount of data!