Title: RE: [xacml] [policy-model] A Proposal
I
think this is the kind of thing that cannot be argued in the abstract. A
complete set of boolean operators can in principle, express any possible policy.
However, it is possible that a particular scheme will make it very awkward to
express common sorts of policies.
What
we need is short example proposals of a possible expression and its semantics,
along with examples of policies hard to express in alternative schemes. Bill did
something of this sort a couple of weeks ago, but I would have liked to see the
intended semantics stated more explicitly.
Hal
-----Original Message-----
From: Simon Godik
[mailto:]
Sent: Thursday, December 06, 2001
5:54 PM
To: 'Tim Moses'; xacml
Subject: RE: [xacml]
[policy-model] A Proposal
Tim,
I
think that 'not' does not substitute for 'deny'. From my point of view 'not'
is just a logical operation.
You
can have 'not' condition in the grant statement and it may or may not
fire. If 'not' something evaluates to false
you
do not get a 'grant'. 'Deny' on the other hand has implications for role
hierarchies and also can have 'not' conditions imbedded
in
it. I agree with Michiharu that it is better to have explicit 'grant' and
'deny' (or some variation thereof)
Simon G.
-----Original Message-----
From: Tim Moses
[mailto:]
Sent: Monday, December 03, 2001
11:20 AM
To: xacml
Subject: RE: [xacml] [policy-model] A
Proposal
Michiharu - Thanks for this proposal on extensibility.
I suspect that we will delay discussion of extensibility points until the
model is settled. However, it will become important at that
time.
In the model, as currently described, we do not include
separate elements for "grant" and "deny". Instead, the "deny"
semantics are provided by "and" and "not" ...
<and>
<predicate>grant_condition</predicate>
<not>
<predicate>deny_condition></predicate>
</not>
</and>
With this approach, no explicit grant element is required:
if the applicable policy evaluates TRUE, then the PDP may return the saml
"permit" status code.
All the best. Tim.
-----------------------------------------
Tim Moses
Tel: 613.270.3183
-----Original Message-----
From:
Michiharu Kudoh [mailto:]
Sent: Monday, December 03, 2001 7:24 AM
To:
xacml
Subject: [xacml] [policy-model] A
Proposal
I drew a picture about the desirable extensibility of XACML
policy model
based on the currently proposed XACML
language document.
(See attached file: ModelProposal.ppt)(See attached
file:
ModelProposal.pdf)
Best regards,
Michiharu Kudo
