Re: [pedantic-web] Re: The OWL Ontology URI

On Mon, May 10, 2010 at 10:25 PM, Pat Hayes <phayes@ihmc.us> wrote:
> Let me give an intuitive case in support of the Nays here. An RDF graph is a
> set, which is not the same as a document, for sure. The *same* graph can be
> encoded in a variety of different syntactic forms.

Try re-running this to show that digital images aren't information resources?

'The *same* digital image can be encoded in a variety of different
syntactic forms (PNG, GIF, JPEG, SVG, ...).

(Or even that books aren't information resources ('the same book can
be encoded in a variety of different forms; both digital
(text,html,pdf and various arrangements of atoms).)

> Consider two documents,
> one in RDF/XML, the other in NTriples, describing the same graph. If we
> identify the document with the graph it describes, then these have to be the
> same. But they aren't the same. So even if a graph is an information
> resource (and I agree that one can make out a case for that position), it
> certainly isn't the same information resource as any document (In RDF/XML or
> NTriples or any other notation) that represents it syntactically. So, one
> ought to use redirection to refer to it, according to http-range-14. So,
> whether its an information resource or not is kind of moot, since even if it
> is, it can't be directly identified by a URI which returns a 200 code.

http://www.w3.org/Icons/w3c_home.png
http://www.w3.org/Icons/w3c_home.gif
http://www.w3.org/Icons/w3c_home

One generic digital resource, two specific 'bags of bits' that encode
it, three URIs and here's the gory details from talking to W3C's
server:

First we make three requests to the server; first time not expressing
a preference towards any type of bag of bits, then we say we prefer
gif, then we say we prefer png:

curl --dump-header h1 -o f1  http://www.w3.org/Icons/w3c_home
curl -H 'Accept: image/gif' --dump-header h2 -o f2
http://www.w3.org/Icons/w3c_home
curl -H 'Accept: image/png' --dump-header h3 -o f3
http://www.w3.org/Icons/w3c_home

This gives us 3 files, two of which are identical in content:

Dan-Brickleys-MacBook-Pro:img danbri$ ls -l f*
-rw-r--r--  1 danbri  staff  1936 14 May 09:07 f1
-rw-r--r--  1 danbri  staff  1865 14 May 09:08 f2
-rw-r--r--  1 danbri  staff  1936 14 May 09:08 f3

If we check the headers, we see that 200 was used each time even when
the bytestream content varied. I believe you're using the word
'document' at least sometimes to individuate about those things. The
variants seem to have the exact same last-modified time; this could
have been because they were part of the same CVS commit action to
w3.org.

Dan-Brickleys-MacBook-Pro:img danbri$ file f*
f1: PNG image, 72 x 48, 8-bit colormap, non-interlaced
f2: GIF image data, version 89a, 72 x 48
f3: PNG image, 72 x 48, 8-bit colormap, non-interlaced
Dan-Brickleys-MacBook-Pro:img danbri$ cat h1
HTTP/1.1 200 OK
Date: Fri, 14 May 2010 07:07:49 GMT
Server: Apache/2
Content-Location: w3c_home.png
Vary: negotiate,accept
TCN: choice
Last-Modified: Mon, 24 Jul 2006 14:58:33 GMT
ETag: "790-4195514757840;48498becf6180"
Accept-Ranges: bytes
Content-Length: 1936
Cache-Control: max-age=2592000
Expires: Sun, 13 Jun 2010 07:07:49 GMT
P3P: policyref="http://www.w3.org/2001/05/P3P/p3p.xml"
Connection: close
Content-Type: image/png; qs=0.7

Dan-Brickleys-MacBook-Pro:img danbri$ cat h2
HTTP/1.1 200 OK
Date: Fri, 14 May 2010 07:08:09 GMT
Server: Apache/2
Content-Location: w3c_home.gif
Vary: negotiate,accept
TCN: choice
Last-Modified: Mon, 24 Jul 2006 14:58:33 GMT
ETag: "749-4195514757840;48498becf6180"
Accept-Ranges: bytes
Content-Length: 1865
Cache-Control: max-age=2592000
Expires: Sun, 13 Jun 2010 07:08:09 GMT
P3P: policyref="http://www.w3.org/2001/05/P3P/p3p.xml"
Connection: close
Content-Type: image/gif; qs=0.5

Dan-Brickleys-MacBook-Pro:img danbri$ cat h3
HTTP/1.1 200 OK
Date: Fri, 14 May 2010 07:08:22 GMT
Server: Apache/2
Content-Location: w3c_home.png
Vary: negotiate,accept
TCN: choice
Last-Modified: Mon, 24 Jul 2006 14:58:33 GMT
ETag: "790-4195514757840;48498becf6180"
Accept-Ranges: bytes
Content-Length: 1936
Cache-Control: max-age=2592000
Expires: Sun, 13 Jun 2010 07:08:22 GMT
P3P: policyref="http://www.w3.org/2001/05/P3P/p3p.xml"
Connection: close
Content-Type: image/png; qs=0.7


Can you re-tell your story in a way that allows the abstract digital
image here to be an information resource? If we substitute RDF/XML for
GIF, NTriples for PNG, and 'digital image' for 'graph' you seem to be
arguing that W3C's Web server is misconfigured, and that the 200 HTTP
answers here are inappropriate. Or am I misreading your point?

cheers,

Dan

Received on Friday, 14 May 2010 08:09:28 UTC