JAX-RS Client to handle SAML (+OAuth2) in SSO

Hi,

I have a third party JAX-RS service that is secured through SAML, I am
trying to access this service through my java application. I have access to
currently logged-in user's Subject. I am kind drawing blank on how I need to
proceed. Should I build a SAMLRequest envelope and send to the service?
Obviously for me call back and human interaction with web-page is not
possible. So, I thought I might need to have SAMLResponse to go along with
my request based on Subject?

With OAuth2, same scenario, but I am trying to access SalesForce. I need to
follow SAML2 Bearer as defined here
http://cxf.apache.org/docs/jaxrs-oauth2-assertions.html but not sure how I
can get my hands on SAML Token?

I think I need a service, given Subject will provide me back with SAML
token, but I would to delegate this responsibility to an IDP to do the task.

Can somebody explain what may be the right flow of actions, and/or point me
to any examples?

Thanks

Ramesh..