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Meaning of a Resource: Comment on 27th June 2003 webarch WD

From: Williams, Stuart <skw@hp.com>
Date: Tue, 15 Jul 2003 16:13:24 +0100
Message-ID: <5E13A1874524D411A876006008CD059F04A07645@0-mail-1.hpl.hp.com>
To: "Ian B. Jacobs (ij@w3.org)" <ij@w3.org>
Cc: "'www-tag@w3.org'" <www-tag@w3.org>

Hello Ian,

In prep for our F2F I've been re-reading the 27th June version of webarch.
I've a number of comments... some editorials/typos and some less significant
techy comments which I'll send separately.

This one I suppose is the biggy...

Regards

Stuart
--
Meaning of a Resource
---------------------
[Apologies... this one's a bit of a rant... ]

The phrase "meaning of a resource" occurs repeatedly throughout the text:

Section 2.1
  a) "URI consumers cannot, in general, determine the meaning of a resource
by inspection of a URI that identifies it."
  b) "Although short, meaningful URIs benefit people, URI consumers must not
rely on the URI string to communicate the meaning of a resource."
  c) "See the section on retrieving a representation for information about
how the meaning of a resource is conveyed."

Section 2.3
  d) "To give these parties the confidence that they are all talking about
the same thing when they refer to "the resource identified by the following
URI ..." the design choice for the Web is, in general, that the owner of a
resource assigns its authoritative meaning and the URIs that refer to it."
  e) "In our travel scenario, the agent responsible for weather.example.com
has license to assign the meaning of the resource and to create the
authoritative representations of this resource."

Section 2.4.1:
  f) "The representations communicate the meaning of the resource."
  g)"Resource descriptions: Owners of important resources SHOULD make
available representations that communicate the meaning of those resources."

Section 3.1:
  h) "As discussed above, the owner of a resource assigns its authoritative
meaning and the URIs that refer to it"
  i) "This meaning is communicated in part through metadata that is part of
the representation, notably the Internet Media Type."

I'm more uncomfortable with some of these than others, in particular those
that speak of the assignment or communication of the meaning of a resource.
For example I can follow the specs. Doing an HTTP retrieval on the URI at
[1] gives me a Content-Type: image/jpeg which by reference to the IANA
registry tells me that this is a jpeg encoded image. Following the reference
to the JPEG specification will tell me how to translate the content into an
array of coloured dots... but none of these specs. will tell me what the
resource means - only how to access a representation of its state.

I'm more comfortable with a) and b) because on the whole they are statements
about the inability of URI to communicate meaning. 

c) is a bit of a travesty in that it suggests that we explain how meaning is
conveyed - which I don't think we do. d) can make its point, that two
identical references refer to the same thing, without needing to speak of
meaning. IMO f) would be better as "Representations communicate the state of
the resource."

g) is a little tangled. Descriptions, representations and communication of
meaning all in one. I think I'd prefer "Resource Descriptions: Owners of
important resources SHOULD make available representations that described
those resources."

d) and h) mention owner assignment of meaning which suggest some explicit
way of expressing or assigning meaning. It seems to me such assignment of
meaning is much more implicit and the meaning itself is far less accessible.

On the whole I'd much rather avoid the attribution of meaning to a resource
unless its really really necessary in the document.

[1] http://www.ibiblio.org/wm/paint/auth/bruegel/babel.jpg
Received on Tuesday, 15 July 2003 11:13:56 GMT

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