refer the links, if you find it useful. I got these informations by google search. If you have seen those links already, sorry man. :-(
I could not find many artifacts which deals with parsing the SAML document. If you have done your work successfully, throw your idea about paring SAML, to perlmonks. that will be useful to all of us.

SAML_Ref_1 SAML_Ref_2