Relevant Standards/Protocols
1.WS-Federation
Define mechanisms to allow different security realms to federate,such that authorized access to resources managed in one realm can be provided to security principals whose identities reside in other realm.
2.SAML
XML-based framework designed to communicate user authenticate,entitlement and attribute information to other entities.
3.OpenID connect
based on OAuth 2.0 allowing developers authenticate their users across we sites and apps without having to own and manager password files.
Allows information from an Identity provider to be used.
4.OAuth 2.0
Included in OpenID and enables a third party application to obtain limited access to an HTTP service on behalf of a resource owner by managing an approval interaction between the resource owner and the HTTP service,or by allowing the third party application to obtain access on its behalf.