hierarchical node id datatype

["Tyson, Paul H" <PTyson@bellhelicopter.textron.com>]

In the 3.0 draft hierarchical profile of 7 November 2008:

Data type for non-XML node ids (section 2.2) is required to be anyURI.
While this might be useful to support some xpath-like operations, it
seems to be overspecified for the basic use case of testing to see if
one resource is an "ancestor" of another.  A string data type would work
as well.

Consider a resource-id "r1", used in two places in a hierarchy:

	http://example.com/path/to/one/r1
	http://example.com/path/to/another/r1

I have a rule that says "permit if resource has ancestor 'path'".

My context handler can supply a bag of resource-ancestor attribute
values ["one","another","to","path"] for resource-id "r1".  But
according to the draft spec I would have to write the rule:

	permit if 'http://example.com/path' anyURI-equal
resource-ancestor

and the context handler would have to supply URI values like
'http://example.com/path', 'http://example.com/path/to', etc.

In other contexts, values like 'path', 'to', etc. would be the actual
resource-id values for these resources.  It would be convenient to use
these values directly as the values of 'resource-parent',
'resource-ancestor', and 'resource-ancestor-or-self'.  This would not
interfere with any existing functionality provided by the hierarchical
profile, because they would be distinguished by a different datatype.

Please consider relaxing the anyURI datatype requirement for non-XML
'resource-parent', 'resource-ancestor', and 'resource-ancestor-or-self'
attribute values in the hierarchical profile.  This would also allow
policies to use other appropriate comparators besides anyURI-equal and
regexp-uri-match.

--Paul Tyson