So, In the first level we have the vocabulary, the pure XML schema. We
can find here SAML 1.1, SAML 2.0, Liberty, Shibboleth(?).... so schemes that
are built above existing ones (I guess SAML is the common base of all of
them). This level defines the vocabulary and the semantic meaning.
SAML
1.1 is a common base for Liberty ID-FF and Shibboleth.
SAML
2.0 is a convergence of the 3 with substantial schema changes across the board
and new profiles created from some of the work done in Liberty &
Shibboleth.
In the second level we have the profiles (?), so, what can be done using
those schemes and how is done; for example, which are the steps must be
performed to do a SSO or actions that are possible (defined) in one "tool" and
not in another. So, Shibboleth defines one way for doing the things and
Liberty another and SAML2.0 another. So, in that level it would be possible to
classify the actions that are possible (SSO, federation,...).
SAML
2.0 has a complete list of the profiles that covers the profiles available in
Liberty and Shibboleth, all of which overlap the more limited profiles available
in SAML 1.1.
I
would recommend that any new work today be done using SAML 2.0 as it's the
result of much experience rolling out SAML 1.1 based systems (including Liberty
and Shibbloleth) in real world environments.
Toolkits for SAML 1.1, Liberty ID-FF and Shibboleth are still valuable
for roll-outs that need compatibility in one of those environments (e.g. adding
a new SP to a Liberty ID-FF Circle of Trust).
Conor
