Use case for IM client to be used in SaaS

In this scenario, how would SAML be implemented-if the fderation would be made up of organisations with different directories, and the IM uses a non-http protocol and uses java. Any help will be useful

XML.org Focus Areas: BPEL | DITA | ebXML | IDtrust | OpenDocument | SAML | UBL | UDDI
OASIS sites: OASIS | Cover Pages | XML.org | AMQP | CGM Open | eGov | Emergency | IDtrust | LegalXML | Open CSA | WS-I