Re: [xacml-comment] What is "URI equality" ?

Hi Steven,

    

    "URI equality" is defined in the URI specification RFC 3986:

      "Uniform Resource Identifier (URI): Generic Syntax"

      http://tools.ietf.org/html/rfc3986

    which in section 6, goes into detail as to what is involved:

      http://tools.ietf.org/html/rfc3986#section-6

    

    The bottom line is that there is no accepted unambiguous way

    to determine absolutely that 2 URIs are "equal", and the 

    objective has been reduced to:

    "Therefore, comparison methods are designed to

       minimize false negatives

       while strictly avoiding false positives.
      "

      http://tools.ietf.org/html/rfc3986#section-6.1

    
    In other words (I interpret this to mean),

    
      
a determination of "equivalent" should, in general,

        be considered to be "accepted as absolutely true", 

      

      
while a determination of "non-equivalent" should,

        in general, be considered to be accepted as "true",

        but, with the qualification that further investigation

        may under some circumstances find that the result

        may be "equivalent" when those additional

        circumstances are included in the evaluation.

    
    Note that the core spec refers to the August 1998 version:

      "Uniform Resource Identifiers (URI): Generic Syntax"

      http://tools.ietf.org/html/rfc2396

    which elaborates less on this issue but does say in section 6:

    "In general, the rules for equivalence

       and definition of a normal form, if any,

       are scheme dependent."

    
    -> XACML 3.0 core spec should be updated to refer to RFC3986,

    which has "obsoleted" RFC2396.

    

        Thanks,

        Rich

    

    

    On 10/25/2011 7:36 PM, Steven Legg wrote:
    
      

      Sections 5.29 and 7.3.4 of the Committee Specification 1 XACMLv3
      core
      

      specification define the matching of Category, AttributeId and
      DataType
      

      XML attributes according to "URI equality". I've always assumed
      that
      

      URI equality was the same as the matching performed by the
      

      urn:oasis:names:tc:xacml:1.0:function:anyURI-equal function, but I
      can't
      

      find anything in the specification to justify that assumption
      since
      

      "URI equality" is not defined anywhere. It would help if the
      specification
      

      clarified what "URI equality" actually means.
      

      

      Similarly, there is also a reference to undefined "string
      equality"
      

      matching in section 5.24.
      

      

      Regards,
      

      Steven