Re: [xacml-comment] empty target evaluation

[Roland Illig <roland.illig@gmx.de>]

Tyson, Paul H schrieb:
> See the 3.0 spec (xacml-3.0-core-spec-wd-06-en.doc), Section 7.6, Target
> evaluation.
> 
> This doesn't seem to account for an empty Policy/Target element.  The
> first example policy (section 4.1.1) shows an empty Target element, with
> the explanation that this policy applies to all decision requests.

For mathematicians and related people, "all of" applied to an empty set
always returns "true", no matter what the predicate is. Therefore I
think your case of an empty <Target> is covered by the specification.

> Also section 7.9, Rule evaluation, doesn't account for a missing Target
> element.  Strictly interpreted, this would mean that a Rule with no
> Target element could never return its Effect value.

It does. In section 5.21 ("Rule"), the specification states: "If this
element is omitted, then the /target/ for the <Rule> SHALL be defined by
the <Target> element of the enclosing <Policy> element." Therefore,
every <Rule> has a <Target>.

> Will the XACML TC consider clarifying the normative sections 7.6 and 7.9
> to specify the evaluation of missing and empty Target elements?

I don't think anything needs to be clarified here, at least not for
people who read such kind of standards documents every day. But I'm not
involved in the committee in any way, so this is just my personal opinion.

Roland