[uf-discuss] Cross-network identification (Was: OpenID)
jpanzer at aol.net
Tue Feb 20 22:10:17 PST 2007
Scott Reynen wrote:
> On Feb 20, 2007, at 6:56 PM, John Panzer wrote:
>> Scott Reynen wrote:
> Here's the purpose of UID from vCard:
>> To specify a value that represents a globally unique
>> identifier corresponding to the individual or resource associated
>> with the vCard.
> So if two hCards have the same UID, they must refer to the same
> person, because otherwise it wouldn't be globally unique. And I
> think that solves the problem Thom described above, unless I'm
> missing why it needs to be specific to OpenID.
Nope, it solves it. OpenID URLs are just one example.
>> I'm thinking here of cases where the target may be an OpenID, but
>> not necessarily provide an hCard.
> UIDs do not need to point to hCards. Nor do they need to be
> OpenIDs. They can do both, but the only requirement is that they be
> globally unique and correspond to the subject of the hCard. And that
> minimal requirement seems to be just enough to solve this problem
> without worrying about what, if anything, is on the other end of the
Thanks. (The thread in the archives was somewhat twisty; the summary is
helpful.) So, rel="url uid" it is.
I think this solves the problem of how to match one hCard up with
another using a convenient unique key well above the 80% level.
One minor point: URLs are unique but not truly persistent. Due to URL
reuse,when trawling through archives you can't assume that UID1 == UID2
means person 1 == person 2 unless both UIDs were minted at the same
time. I'd probably solve this heuristically if ever necessary, but: Is
it worth an implementor's warning somewhere?
Interestingly, the vcard people seemingly dealt with this issue, because
they edited  "persistent, globally unique identifier" prior to the
final RFC draft.
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