Re: [xacml] Proposal on item 7 ConditionReference

[Polar Humenn <polar@syr.edu>]

On Wed, 10 Dec 2003, Michiharu Kudoh wrote:

> OK. Could you briefly summarize pros and cons of both ways, please? Just
> for people who wants to understand the difference between two
> approaches. I will post the two proposals (only boolean val ref or any
> val ref) with the comparison you will make. Actually I can live with
> both.

The "pros" of VariableDef/VariableRef is that you have ONE construct for
associating a variable identifier with a value expression. And one
construct to reference that expression. Simplicity.

I can't really see any "cons" with the approach.

The use of ConditionDef/CondtiionRef ApplyDef/ApplyRef, is that you have
two constructs to do basically the same thing as above, except that one is
restricted to boolean typed expressions, and the other is restricted to
function definitions.

I have a hard time thinking of "pros" to this approach, in relation to the
"cons", which I think are unnecessary restrictions.

Since we have a formal type system within XACML, the type checker will
still have to check that the expression associated with a ConditionDef is
infact a boolean typed expression, and the expression that is associated
with the ApplyDef still has to match the type expression where it is used.
Both approaches must go through the same type rigor.

Also, both appraoches have to deal with use of undefined reference names,
and possibly "unused" defintiions.

Cheers,
-Polar