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

Tantek Ç elik tantek at cs.stanford.edu
Tue Apr 25 12:43:32 PDT 2006

On 4/25/06 8:45 AM, "Scott Reynen" <scott at randomchaos.com> wrote:

> On Apr 25, 2006, at 9:21 AM, Tantek Çelik wrote:
>> The closest thing to UIDs that current publishers of hCards are
>> publishing
>> are their unique URLs within their sites (e.g. Upcoming and
>> Eventful venues
>> and events).
> I have a concern that using URLs as UIDs will prevent them from being
> globally identifiable,

This is a joke, right?  URLs are by design global.  The opposite of your
concern is actually true: URLs will tend to make UID *more* globally

> 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).

> 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.

> which I thought was the primary purpose of the UID.

Not the primary purpose of the UID.

The purpose is to make sure that two *different* events don't use the same

Having two representations of the same event, but with different UIDs is
actually ok.  Systems can relatively easily deal with relating multiple
occurrences of the same event.

> I expect URLs as 
> UIDs would allow us to identify the same event from the same site,


> but not across multiple sites because each site will use its own URL
> as the UID.

That's a straw-man argument that's assuming one particular implementation
and then saying that implementation won't work.

Each site could for example use its own URL as the UID, *and* keep track of
other URLs to the same event.  Presto, problem solved.

> And in the case of book citations, aren't ISBNs the closest thing to
> UIDs currently published?

Though most press and ecommerce services on the web *do* use the ISBN as
part of the product description, most actual *citations* of books I've seen
on the Web do not actually include the ISBNs.

So it is a bit of a mixed bag.  In as much as microformats are targeted to
individual publishers, ISBN doesn't matter because they're not publishing it
today.  However, as with hReview, we do want to attempt some level of
interoperability with existing large scale publishing sites as well, and
thus ISBN makes sense to include as an optional component.  In addition, as
part of that work, if we make it *easier* for individual publishers to
include the ISBN as a UID, then perhaps they may do so more often in the



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