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Re: larry's position on URIs as names

From: Jonathan Rees <jar@creativecommons.org>
Date: Mon, 17 May 2010 14:50:54 -0400
Message-ID: <AANLkTikHD_VUb4AX7mucSjHnGexTG_eS2IN3fx2dvWqk@mail.gmail.com>
To: Larry Masinter <masinter@adobe.com>
Cc: www-tag@w3.org
Larry,

The question I asked you below was not rhetorical. Your answer will
help me to prepare for our June F2F.

Thanks
Jonathan

On Sat, Mar 27, 2010 at 7:51 PM, Jonathan Rees <jar@creativecommons.org> wrote:
> Larry,
>
> I wanted to ask this while it's still fresh... at my presentation on
> web semantics I was making the point that GET/200 exchanges
> ("corresponds to" relationships in 2616 parlance) are of little use on
> their own in discerning what entity the "URI owner" means to name with
> the URI, since any set of responses is compatible with the entity
> being a wide variety of things.  You made a comment about ambiguity
> that I think was in agreement with this.  But I wasn't clear on your
> exact position around the use of http: URIs as names because, as I had
> just arrived at (3) below, providing a list of possible sources of
> "other evidence", you appeared to disagree with one of my premises.  I
> suspect that was a misunderstanding.
>
> Can you tell me which of the following most closely matches your view
> of best practice?
>
> 1) http: URIs don't ever make reliable names/designators for use as
> the subjects of metadata assertions.  Use tdb: or guids or ____ instead.
>
> 2) http: URIs make reliable names only when HTTP exchanges with the
> URI as request-URI play no role in determining what they name.
>
> 3) http: URIs make reliable names but only in the presence of evidence
> other than HTTP exchanges with the URI as request-URI.  (If exchanges
> are useful it's only when they're used in combination with that
> evidence.)
>
> 4) http: URIs make reliable names.
>
> A consequence of 2) might be, for example, that if you knew (via
> independent communication with the "URI owner") that
> http://example.com/x was intended to name some unchanging particular
> PNG file, and did a GET soon thereafter on http://example.com/x and
> got a PNG file, you could not infer that http://example.com/x was
> intended to name *that* PNG file, absent other metadata.  Whereas with
> 3) you could.
>
> If that's not good enough, the "other evidence" in 3) might be an SLA
> that you and the URI owner have entered into that guarantees response
> uniqueness over some period of time ("trust"), or metadata giving
> enough checkable information about the image (e.g. a date/time or
> checksum) that the chance of accidental collision is satisfyingly
> small (verifiability).  Would evidence like this, in addition to the belief
> (above) that the representation is fixed, enable use of HTTP
> exchanges as a way to help figure out what entity is meant?
>
> Just trying to figure out where you set the bar.
>
> Jonathan
>
Received on Monday, 17 May 2010 18:57:32 GMT

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