"uid" microformats? (was Re: [uf-discuss] ISBN mark-up)

Scott Reynen scott at randomchaos.com
Tue Apr 25 13:35:55 PDT 2006

On Apr 25, 2006, Tantek Çelik wrote:

> We *want*
> resources that can be identified by network location and thus a  
> system that
> shows a bias *for* that is a *good* thing.

Is the proposal that UIDs SHOULD be URLs or UIDs MUST be URLs?  If  
it's MUST, that would seem to discourage use of microformats to  
markup content that doesn't exist at a canonical URL.

>> many well-established identifiers are not based on URL. e.g. In a
>> typical library application, we really want to identify the books in
>> Amazon and local catalog are referencing same thing,
> Ah, you just introduced a new requirement, and perhaps that is  
> where the
> disconnect is.

I assumed the same use case.  This is all I've ever seen UIDs used  
for.  What is the other use case?

> The requirement that we are looking at is: globally unique, that  
> is, two
> *different* events/contacts don't end up using the same UID.   
> That's it.

Couldn't we more simply give each event an ID attribute and  
accomplish that?

>> I have a concern that using URLs as UIDs will prevent them from being
>> globally identifiable,
> This is a joke, right?

Requesting feedback and then responding like this just seems mean- 
spirited to me.

> URLs are by design global.  The opposite of your
> concern is actually true: URLs will tend to make UID *more* globally
> identifiable.

URLs are inherently globally unique, but URLs are only globally  
identifiable if people use them like that, and I doubt people will.

>> When Eventful is adding an event already found on Upcoming, I
>> would expect Eventful to be more likely to assign a UID of
>> 123872138623 than http://upcoming.org/event/123872138623/
> In speaking with both the Upcoming developers and the Eventful  
> developers
> this is not the case.
> It is *much* easier and more natural to publish and convey a notion  
> of a
> "permalink" for an event or venue, and then mark that up as its  
> UID, than to
> expose random gibberish UIDs to the user (whether numbers or some  
> other
> opaque sequence).

Right, but one involves pointing to a competitor and the other  
doesn't, and I think that difference has a real-world effect on  
people's behavior.

>> Both Upcoming and Eventful have event IDs that are part of event
>> URLs, but don't associate the events with a particular domain.  The
>> domain association ensures the IDs are unique, but it seems to do so
>> at the expense of identifying multiple copies of the same event,
> Not a requirement.  Identifying multiple copies of the same event  
> can easily
> be done by implementations.  E.g. event aggregators can keep track  
> of *all*
> the URLs that an event has when it is found across different sources.

RFC 2445 says UID "MUST NOT occur more than once."  Are we changing  
this in hcalendar?


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