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Re: URI: Name or Network Location?

From: Benja Fallenstein <b.fallenstein@gmx.de>
Date: Fri, 23 Jan 2004 17:36:32 +0100
Message-ID: <40114D90.307@gmx.de>
To: Sandro Hawke <sandro@w3.org>
Cc: Patrick Stickler <patrick.stickler@nokia.com>, www-rdf-interest@w3.org

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Hi Sandro,

I can't answer for Patrick, but I have my own internally consistent
views of this, which I hope may be of interest :-)

Sandro Hawke wrote:
| While you're on the subject, and because I know you have seriously
| consistent views on this: what does the word "representations" mean
| there?  My gray understanding is the community on the whole has no
| consensus here, so a not-well-defined term is used.  But I suspect it
| is well-defined for you.

For me, generally, a representation is something that the "owner" of a
URI thinks is useful for a client to serve in response to a GET request
on that URI. Usually, it is what the "owner" wants to appear in a
browser when a user types the URI into the address bar (although this is
not the only use; an RSS feed will more often be consumed by an
aggregator than shown in a browser).

This definition is intentionally "backwards," i.e. based on the
interests of the URI owner rather than on the direct semantic
relationship between resource and representation. I believe that URI
owners should be able to experiment with this.

However, I think that almost all representations will fall in one of two
categories:

- - Instance: The resource is a document of some kind, such as a textual
document or a photo. The representation is a byte sequence that encodes
the resource in some digital format, which can be presented to a user. A
resource can have different instances, which can vary slightly (GIF vs.
PNG -- same pixels, different format) or greatly (different translations
of the Bible). The document can also be "this particular JPEG file," in
which there would be only one instance representation, which would be a
bit-equal copy of the JPEG file.

- - Description: The *representation* is a document that gives the user
some information *about* the resource. The resource itself can be
anything. For example, the RSS feed of a blog would be a possible
description of the blog itself, as would be the blog's "About" page.

An interesting thing to note is that even digital documents can usefully
have 'description' rather than 'instance' representations. E.g. I would
believe it to be useful if haskell.org assigned
http://www.haskell.org/definition/ as the canonical URI for identifying
the Haskell report plus addenda &c. Putting the URI into a browser
brings up a page that links to different HTML, PS, and PDF versions of
the report.

| Try replacing "representations of" with
|
|    (1) "content (MIME Entities) associated with"

I guess this can be read as being equivalent to my general definition,
if you see "associated" as "whatever the URI's owner sees fit as an
association."

|    (2) "serializations of"

This would be my 'instance' type, which I see as only one possible type
of representation.

Cheers,
- - Benja
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Received on Friday, 23 January 2004 11:46:41 GMT

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