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From Stefano Mazzocchi <stef...@apache.org>
Subject Re: UUIDs, URIs, handles and so forth
Date Sun, 10 Apr 2005 14:45:10 GMT
Roy T.Fielding wrote:
> On Apr 9, 2005, at 9:23 AM, Stefano Mazzocchi wrote:
> 
>> Sure it's easy to add a property 'handle' to a node and model it that 
>> way, but it would be way more elegant (and more future proof, since 
>> I'm already thinking about exporting that content as RDF, were the 
>> URIs are king) if it was possible for JCR to allow *you* to pick the 
>> UUID for the node.
> 
> 
> Why don't you just set a property for an external reference name?
> 
>> So, my question is: is it possible to specify the node UUID 
>> externally? (as long as local unicity is guaranteed, obviously)
> 
> 
> Not really, since fast implementations will depend on it being a
> fixed-length number (internally) rather than a string.

Oh, c'mon, that's totally bogus: do a hash on the ID if you need a fix 
number.

> In any case,
> I would think that you would eventually want multiple persistent
> identifiers for a resource, particularly since some identifiers
> must change when the bits change whereas others only change when
> the semantics change.

Ok, here you're talking. Makes perfect sense.

> BTW, UUIDs are not globally unique over time -- only for a decade
> or so based on common implementations, and even less than that if
> the implementation is stupid.  They are completely unsuitable as
> persistent names.

Are they at least locally unique over time? I mean, if I had a URI like

  http://your.domain/uuid/[UUID]

would that be unique? I'm asking because I'm thinking of ways to encode 
the 'system' view of the JCR tree into RDF and I need to make sure that 
I have a way to refer to each and every node in a sound way.

-- 
Stefano.


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