Subject: [VCARDDAV] UID - why singular, not plural/ multiple?

From: "Andy Mabbett" <[email-masked]>
Date: Sun, 25 Jul 2010 13:23:03 +0100

I notice that the latest draft says of UID:

   Purpose:  To specify a value that represents a globally unique
      identifier corresponding to the individual or resource associated
      with the vCard.

   Value type:  A single URI value.

   Cardinality:  (0,1)

   http://tools.ietf.org/html/draft-ietf-vcarddav-vcardrev-12#page-47

Why is that a singular property? Why should a user not be able to record
more than one UID, where such exist?

For example, UIDs for the playwright William Shakespeare include:

   *   http://d-nb.info/gnd/118613723
   *   http://errol.oclc.org/laf/n78095332.html
   *   http://viaf.org/viaf/96994048
   *   http://dbpedia.org/page/William_Shakespeare
   *   ...

Have I misunderstood the purpose of UID?

-- 
Andy Mabbett
@pigsonthewing
http://pigsonthewing.org.uk

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From: Simon Perreault <[email-masked]>
Date: Sun, 25 Jul 2010 14:33:57 +0200

> Have I misunderstood the purpose of UID?

Yes, I think you did. The above are not UIDs, they are locators. Pretty much
like the difference between URL and URN.

If you make up an example involving vCards I'll be glad to explain it further...

Simon
-- 
NAT64/DNS64 open-source --> http://ecdysis.viagenie.ca
STUN/TURN server        --> http://numb.viagenie.ca
vCard 4.0               --> http://www.vcarddav.org

---

From: "Andy Mabbett" <[email-masked]>
Date: Sun, 25 Jul 2010 14:45:56 +0100

On Sun, July 25, 2010 13:33, Simon Perreault wrote:
> Yes, I think you did. The above are not UIDs, they are locators. Pretty
> much like the difference between URL and URN.

My assumption was derived from this description in the hCard microformat
spec:

   UID in vCard simply becomes another semantic applied
   to a specific URL (or EMAIL) for an hCard.

   http://microformats.org/wiki/hcard#More_Semantic_Equivalents

and this, from an appendix to that spec:

   In addition, such link(s) in hCards to the canonical URL for
   a person on that site should also have the classname of "uid".

   http://microformats.org/wiki/hcard-examples#Canonical_Profiles_on_Sites

Together with this from the same appendix:

   <a rel="me" class="url uid" href="http://flickr.com/people/tantek/">
     Flickr profile
   </a>

   Such a "url" + "uid" property could also be used by a site as
   that person's OpenID URL.

Similar examples are given on:

   http://microformats.org/wiki/representative-hcard-authoring

Perhaps that section should include reference to an RFC (or other
resource) which defines UID in the strict sense meant there?

> If you make up an example involving vCards I'll be glad to explain it

Thank you; I'll do more reading before I trouble you further on that point.

However, should we not consider (not least given the growing importance of
linked data) a vCard property for URLs which act as identifiers (in the
looser sense, such as the Shakespeare examples above), as opposed to the
URL of the subject's own website? The use of such URLs would facilitate a
greater amount of matching, even in cases where UIDs are not available.

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From: Simon Perreault <[email-masked]>
Date: Sun, 25 Jul 2010 16:02:17 +0200

> greater amount of matching, even in cases where UIDs are not available.

You just described the SOURCE property! ;)

Simon

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From: Renato Iannella <[email-masked]>
Date: Mon, 26 Jul 2010 12:26:37 +1000

Hi all - this discussion has slightly confused me ;-)

From my understanding of the UID property, it is a URI that represents a globally unique identifier corresponding to the individual.

A URL is a valid URI.

So, if the owner of the vcard says the UID is "http://shakespeare.com", then that is it, right?

Of course, we recommend UUIDs but any URI is valid, as by definition, a URI is a globally unique identifier.

Cheers

Renato Iannella
http://renato.iannella.it

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From: Simon Perreault <[email-masked]>
Date: Mon, 26 Jul 2010 09:18:40 +0200

> Of course, we recommend UUIDs but any URI is valid, as by definition, a URI is a globally unique identifier.

Absolutely. It depends on how you interpret the URI. In the context of a UID,
it's not supposed to be dereferenced.

Simon

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From: Renato Iannella <[email-masked]>
Date: Mon, 26 Jul 2010 21:34:11 +1000

> it's not supposed to be dereferenced.

Should we say that in the spec then?

Cheers

Renato Iannella