Re: [xacml] Make "*-on-and-only" an AttributeDescription option

[Polar Humenn <polar@syr.edu>]

What is an AttributeDescriptor?

Do you mean AttributeDesignator or have I missed something?

-Polar

On Thu, 17 Jun 2004, Anne Anderson wrote:

> I would like to propose that we add an optional "OneAndOnly" XML
> attribute to the <AttributeDescriptor> element.  If this
> attribute is "true", it causes the <AttributeDescriptor> to
> evaluate to a single element of its DataType, rather than a bag
> of such elements.  If this XML attribute is used, and the
> <AttributeDescriptor> matches no element or more than one
> element, then the evaluation result will be "Indeterminate".  The
> default value of the OneAndOnly Attribute is "false".
>
> The intent is that
>
>   <SomeAttributeDescriptor AttributeId="x" DataType="y" OneAndOnly="true"/>
>
> be exactly equivalent to
>
>   <Apply FunctionId="y-one-and-only">
>      <SomeAttributeDescriptor AttributeId="x" DataType="y""/>
>   </Apply>
>
> Rationale:
>
>   All our standard functions except for the specific bag
>   functions expect a single value, so the case for expecting and
>   wanting a single attribute is extremely common.  It is awkward,
>   verbose, and probably confusing to wrap all instances of
>   <AttributeDescriptor> with an <Apply> of a "*-one-and-only"
>   function.
>
> Anne
> --
> Anne H. Anderson             Email: Anne.Anderson@Sun.COM
> Sun Microsystems Laboratories
> 1 Network Drive,UBUR02-311     Tel: 781/442-0928
> Burlington, MA 01803-0902 USA  Fax: 781/442-1692
>
>
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