Re: URIs quack like a duck

On Sun, Jun 04, 2000 at 02:29:14PM -0400, Dan Brickley wrote:
>On Sun, 4 Jun 2000, Michael Mealling wrote:
>>On Sun, Jun 04, 2000 at 12:39:00PM -0400, John Cowan wrote:
>>>Michael Mealling scripsit:
>>># Not all resources are network "retrievable"; e.g., human beings,
>>># corporations, and bound books in a library can also be considered resources.
>>>
>>>So if everything is a Document, are you and I Documents too?
>>>(When you prick us, do we not bleed?)
>>
>>Yep. I'm actually in the midst of registering a URN namespace that is
>>specifically for assigning names or individuals and organizations.
>>And, until we develop matter transporters, you and I are decidedly
>>not retrievable via the network. But I can assign myself a URI and
>>thus allow the web to talk about me.
>>
>>So where do I and Tim disagree here?
>
>Imagine someone else creates another URI scheme, also used for naming
>individuals and/or orgs. And that some Web data uses your scheme to talk
>about me as urn:mm-agent-namespace:034543532423432 and some other data
>uses person:uk:nx-930366b. 
>
>We all(?) agree that there is just one flesh and blood person being named.

No we don't. If the only information you have is that there are these two
URIs then they are talking about two seperate Resources. We actually
depend on it since we will allow anyone to aquire several URNs for
themselves, each one being wholly seperate. They all name the
same person but no one knows that unless THROUGH SOME OTHER OUT OF BAND
MECHANISM, the person being named tells you so.

>We all(?) agree that the URI spec allows us to use URIs to name persons,
>and that here we see two such names associated with the same flesh and
>blood person.

Unless someone tells you that via some other method, you cannot assume
that at all. Its the difference between syntactic equivalence
and functional equivalence. Even the namespace doc got this semi-right
when it says this:
"Note that URI references which are not identical in this sense may in 
fact be functionally equivalent".

>Some of us read the URI spec as saying that there are two capital-R Web
>Resources being named here. (I think TimBL is in that camp.)

Yes. There are two distinct Web Resources here. Some other system may
tell you in which ways they may be equivalent but based on just the 
URI itself, you can't know any other kind of equivalence...

>Some of us read the URI spec as saying that there is one Resource, and it
>has two URI names associated with it on the Web. I used to think I was in
>that camp. Now I'm agnostic w.r.t. trying to fathom the proper reading of
>that document.

I admit that we could have been clearer in this regard. I'm actually
going to try my hand an an annotated version of 2396 as a first
stab at a re-write...

>>From an RDF perspective, this topic is proving a real implementation
>headache. There's one of something (flesh and blood entity) and two of
>something else (Web names for that entity, aka URI). There seems to be
>utter confusion in the community as to whether we have one Resource (the
>person), two Resources (one each for the two URIs), or even three.

You have to decide in which universe you live and how you describe it.
The Web is defined to be a space where you can talk about things only
by their identifier. You can go up a few 'layers' and start finding
out things about _functional equivalence_ but still, as far as the
web is concerned, they're distinct. 

Now if you assume you're out here in teh real world, sure, its one
Resource. But computer and networks can't model reality yet...

-MM


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Michael Mealling	|      Vote Libertarian!       | www.rwhois.net/michael
Sr. Research Engineer   |   www.ga.lp.org/gwinnett     | ICQ#:         14198821
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Received on Monday, 5 June 2000 10:02:38 UTC