W3C home > Mailing lists > Public > www-tag@w3.org > September 2003

RE: Liberal "URI assignment policies" will create confusion?

From: Ossi Nykänen <onykane@butler.cc.tut.fi>
Date: Thu, 18 Sep 2003 12:34:02 +0300 (EEST)
To: "Williams, Stuart" <skw@hp.com>
Cc: www-tag@w3.org
Message-ID: <Pine.GSO.4.58.0309181228490.8726@butler.cc.tut.fi>

My original "complaint" is that instead of (W3C) saying something like
"sure -- you MAY invent any URI spelling (within your authority) as you
wish", I would appreciate a more constructive statement like "yes, we are
actually promoting consistent, long-term URI name bookkeeping (for
denoting certain kinds of Web resources); here are guidelines how it could
be done...". More formal the better.

Some resources are to be scrapped or versioned for sure -- to me it would
make lot of sense to (uniformly) recognise this at the Webarch level (a
cheap way might be an add-on to the URI spelling; which of course is only
one alternative). It might be a bit tricky, of course, but then, few
things aren't. (Say, like profiling an ISO standard: now that's tricky.)

On Wed, 17 Sep 2003, Williams, Stuart wrote:

> ...
> The content of an advertisment can change.
> ...

True, but there are two cases: 1) changing an "existing" advertisement A
and 2) publishing a new one A' (and perhaps throwing the old advertisement
A away).

In other words, if the principle "Use URIs: All important resources SHOULD
be identified by a URI." is used, authors are effectively forced to invent
ad hoc versioning systems (plural) in order to do URI bookkeeping (both A
and A' to be preserved). And the term "MAY" in 1.1.2 in [1] seems like
dodging the real issue.

Clearly both of the individual advertisements (A and A' in the case 2
above) are important since they might be legally binding etc. And in this
case, the difference between a resource and its representation is also
pretty thin.

...

And you are indeed right, sometimes I do get confused with the terms like
"thing", "object in the networked information system", "resource",
"representation", "metadata about the representation", and "relationship
between things". Well, here are the definitions (of course, all of them
are from WDs):

From [1] (Web-arch):

(a) Objects in the networked information system called resources are
identified by Uniform Resource Identifiers (URIs).

(b) A representation is data that represents or describes the state of a
resource. It consists of: [...] Electronic data expressed in one or more
formats [...and] Metadata about the representation, such as the Internet
Media Type [...]

From [2] (RDF Semantics):

(c) The [RDF] semantics treats all RDF names [i.e. URI references or a
typed literals] as expressions which denote. The things denoted are called
'resources', following [RFC 2396], but no assumptions are made here about
the nature of resources; 'resource' is treated here as synonymous with
'entity', i.e. as a generic term for anything in the universe of
discourse.

And finally, from [3] (RDF Concepts):

(d) The assertion of an RDF triple says that some relationship, indicated
by the predicate, holds between the things denoted by subject and object
of the triple.

...in other words you can't e.g. use RDF to describe the representations
(of resources) since by (d) RDF asserts relationships between things,
which by (c) are resources, and by (a) and (b), resources and
representations are different (at least by your interpretation). Or then
representations indeed are (conceptually) resources, at least in certain
context ...to be considered as resources of certain type.

I don't want to see all the specs rewritten but yes: I am a bit confused.

Cheers,

--Ossi

[1] http://www.w3.org/TR/webarch/
[2] http://www.w3.org/TR/2003/WD-rdf-mt-20030905/
[3] http://www.w3.org/TR/2003/WD-rdf-concepts-20030905/


--
Ossi Nykänen                              Tel   +358 3 3115 3544
Tampere University of Technology          Fax   +358 3 3115 3549
DMI / W3C Finnish Office                  Email ossi@w3.org
P.O. Box 553, FIN-33101 Tampere, Finland  Web   www.w3c.tut.fi
Received on Thursday, 18 September 2003 05:34:09 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 26 April 2012 12:47:20 GMT