Dealing with unauthenticated users

[Michael Freedman <Michael.Freedman@oracle.com>]

I have cc'd this e-mail to the entier list because I think folks might 
be interested in general -- I apologize up front if this is something 
you don't want to see.

We have discussed that though the specification doesn't define the 
UserContext [userContextKey and userCategories] as carrying security 
information, we expect some producers to use this application level 
information to satisfy its needs.  Currently, the userContextKey is a 
required field.  Hence the current way a consumer indicates it doesn't 
know the users identity is by passing a null userContext.  This however 
prevents the consumer from defining/mapping user categories to 
unauthenticated/unknown users.  However consumers often represent this 
class of user just so some control can be defined on this class.  For 
example, control as represented by wsrp:minimal user category.  

So the questions is, do we want to support defining/using user 
categories on public/guest users?  If so, how do we deal with the 
producer/JSR 168 interoperability problem wherein the producer uses the 
userContext/userContextKey field to establish whether its communicating 
with an authenticated user [through its trust relationship with the 
consumer]?  Wouldn't we need to define a special token value for 
userContextKey that all producers could safely use to mean the 
application hasn't established the identity of the user but oh by the 
way here are the user categories that relate to anyonymous users?  I 
would suggest we use the convention that an empty string "" as the 
userContextKey indicates such a user.  What do others think?
    -Mike-