How to handle Policy Exception handling

Hello,

I am trying to build a policy execution container and
trying to nail down all the use cases and i came
across the following use case

The user wants to define a Authentication Policy which
does
1) authenticate the user
2) on Authentication failure Log a specific message 

In other words how do i define "policy assertion
exception handling".
I can solve the problem that i have  in my hand by
definition a custom exception handling assertion and
my engine understanding it but would like to know

a) what is the direction from ws-policy to address
this  use case?
b) does exception handling belong to a policy or it
belongs to a message/process flow (bpel has exception
handling)
but from a user perspective the above is a Policy so
what is the thought process for this use case going
forward . 

thanks & regards
Manoj







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