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RE: URNs, Namespaces and Registries

From: David Orchard <dorchard@bea.com>
Date: Mon, 14 Aug 2006 11:54:05 -0700
Message-ID: <E16EB59B8AEDF445B644617E3C1B3C9C02140BD7@repbex01.amer.bea.com>
To: "Schleiff, Marty" <marty.schleiff@boeing.com>, <www-tag@w3.org>

Those are good points.  The use of metadata in uris and constraints by
the authority to approximate myri schemes isn't discussed in perhaps
enough detail in the finding.


> -----Original Message-----
> From: www-tag-request@w3.org [mailto:www-tag-request@w3.org] 
> On Behalf Of Schleiff, Marty
> Sent: Friday, August 11, 2006 11:22 AM
> To: www-tag@w3.org
> Subject: RE: URNs, Namespaces and Registries
> Comments on section 2.6 (Uniform access to metadata) of URNs, 
> Namespaces and Registries [1].
> Perhaps the XRI notion of metadata differs from the other 
> myRIs. It certainly differs from what I've read in "The use 
> of Metadata in URIs"
> [2].
> It's probably important to understand that XRI is not a 
> single type of identifier; rather, it's more of a framework 
> within which other kinds of identifiers can be expressed. 
> OIDs, IP address, distinguishedName, UUID, HIT, identifiers 
> that are case sensitive, identifiers that are case 
> insensitive, numeric identifiers, and others can all be 
> expressed within the XRI framework. Now let's move on to 
> XRI's notion of metadata. 
> XRI metadata consists of tags/indicators/data about the 
> _identifier_ instead of data about the named resource. 
> Identifier metadata informs XRI-aware applications about 
> characteristics of the identifier.
> Following are examples of why identifier metadata might be usefull:
> To inform the application about normalization and matching 
> rules for an identifier expressed in an XRI. Simple string 
> matching would not recognize that the following two DNs are 
> equivalent:
>      cn=smith\, joe,ou=Marketing;   O=Acme; c=us
>      CN="Smith, Joe";   OU=marketing,o=acme, c=US
> To inform the application of inherent features of an 
> identifier such as an embedded check digit or some crypto 
> properties like the identifier is a hash of the subject's 
> public key. For the application to derive any value from such 
> features, the presence of such features mst be conveyed to 
> the application.
> To inform the application of non-http resolution capabilities 
> that might be native to the identifier (e.g., DNS, or Open 
> Group's notion of UUID pair where one UUID represents the 
> issuing authority that assigned the other UUID to a subject). 
> To inform an application of how to treat an identifier like 
> "" -- such an identifier in an XRI will let the 
> application know if it can ping the value as an IP address, 
> or treat it like an OID, or treat it in some other fashion.
> I think the statement in URNsAndRegistries [1] that "Naming 
> authorities can impose such constraints on the http: URIs 
> under their control"  also covers XRI metadata requirements 
> if we use a naming authority like "http://xri.net" instead of 
> the "xri:" scheme.
> [1] http://www.w3.org/2001/tag/doc/URNsAndRegistries-50.xml
> [2] http://www.w3.org/2001/tag/doc/metaDataInURI-31
> Marty.Schleiff
Received on Monday, 14 August 2006 18:55:16 UTC

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