How to access Shibboleth as SP built in variables in your Application?

Most of the variables created by the SP are controlled by you, and correspond to mapped attributes. A few are built into the SP and can't be renamed.

Variable	Meaning
Shib-Application-ID	The applicationId property derived for the request.
Shib-Session-ID	The internal session key assigned to the session associated with the request.
Shib-Identity-Provider	The entityID of the IdP that authenticated the user associated with the request.
Shib-Authentication-Instant	The ISO timestamp provided by the IdP indicating the time of authentication.
Shib-Authentication-Method	The AuthenticationMethod or <AuthnContextClassRef> value supplied by the IdP, if any.
Shib-AuthnContext-Class	The AuthenticationMethod or <AuthnContextClassRef> value supplied by the IdP, if any.
Shib-AuthnContext-Decl	The <AuthnContextDeclRef> value supplied by the IdP, if any.

We can access all these variable as header in JAVA application.

Eg:

    request.getHeader("Shib-Identity-Provider")

   request.getHeader("Shib-Session-ID")

Reference:

https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPAttributeAccess