how to get NameId from SAML2 post subject?

[Peter Schober]

* xiangdong xu <xuxian at yahoo.com> [2012-05-24 03:45]:
> I am trying to get NameId out of a SAML2 post. However, I could not
> find any document how to do that with SP configuration. 

The default configuration is such that a NameID of 'persistent' name
format it available as "persistentId" in the webserver's environment
automagically (i.e., without requiring any configuration changes).
If you want to influence which parts of a SAML2.0 NameID get used and
how (or want to map a NameID of 'unspecified' name format, for example),
look at your attribute-map.xml (or the documentation, obviously),
-peter