You can click on the Google or Yahoo buttons to sign-in with these identity providers,
or you just type your identity uri and click on the little login button.
by writing some doc about it. But maybe it's already done.
What part of "It was redundant with session_data and transaction_data" is unclear ?
that's not documentation.
Task #3923674 - latest update on 2014/06/06, created on 2014/06/04 by Sylvain Thenault