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Subject: RE: [xacml] [Polar] PH09: New section 7.4.2 Attributes
There is exactly the same performance overhead to perform this check whatever the semantics of this expression is. Somewhere, somehow you will have if(size == 1) expression evaluated. Implicit application, as I suggested, will allow the implementation to optimize it a bit though - to avoid an extra value copy probably.. Daniel. -----Original Message----- From: Seth Proctor [mailto:seth.proctor@sun.com] Sent: Monday, November 04, 2002 9:59 AM To: Simon Godik Cc: xacml@lists.oasis-open.org Subject: Re: [xacml] [Polar] PH09: New section 7.4.2 Attributes On Mon, Nov 04, 2002 at 09:39:22AM -0800, Simon Godik wrote: > use type-one-and-only function: > > apply string-equal > apply string-one-and-only > subj-attr-desig attrid string-uri issuer must-be-present > attr-val string-uri hello And are you ok with the performance/size overhead this incurs? Nearly every function in the spec is defined to take single values, which means that nearly every AD/AS used in a policy will need this wrapping. Also, this means that a function will never know about an empty bag and be able to treat it differently than an error case, since *-one-and-only is defined to return Indeterminate if no values are found. When I originally rasised that issue, the TC was adamant that functions should have the ability to differentiate between an error case and an empty bag. A second, though much smaller problem, is that it effectively requires coders who create new attribute types to create a *-one-and-only function for each attribute type they invent if they want this behavior. Why not just have language in the spec that lets a PDP do this implicitly, and save on size, computation time, complexity, and flexibilty? seth ---------------------------------------------------------------- To subscribe or unsubscribe from this elist use the subscription manager: <http://lists.oasis-open.org/ob/adm.pl>
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