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part 2, 5.1 "the response payload is a representation of the target resource"

From: Jonathan A Rees <rees@mumble.net>
Date: Tue, 7 Feb 2012 10:08:52 -0500
Message-ID: <CAGnGFMKeHW2bPr5WL-HXD=rAJvwp+HMYu5FeCccjypNxWV-48g@mail.gmail.com>
To: ietf-http-wg@w3.org
Cc: "Henry S. Thompson" <ht@inf.ed.ac.uk>
The confusion I pointed out in 7.3.4 is also present in section 5.1. We have

http://tools.ietf.org/html/draft-ietf-httpbis-p2-semantics-18#section-5

"1.  If the response status code is 200 or 203 and the request method
      was GET, the response payload is a representation of the target
      resource."

If you mean "representation" in an ordinary-language sense, then the
status code only *indicates*, it does not *imply*. So we cannot
conclude that the payload is a representation of the target resource;
we can only conclude that the server *says* it is a representation of
the target resource. We would need more information, such as trust in
the server, to conclude that it actually *is* a representation. (This
is true even if the server is the origin server.)

In the language of that section, one would say "the response payload
is a representation *associated with* the target
      resource [by the server]" - i.e. the server has made the
association, and that association might be incorrect, and that's
OK, it's up to the application to sort it all out.

There is another solution to this problem besides changing 5.1 and
7.3.4: You could define "representation" as a term of art, making it a
static property of HTTP exchanges, one that is decided by fiat by the
server, not an ordinary-language word. This would be rather tricky I
think, and again I don't think it's what you intend, but I'm not sure.

Yet another solution would be to say that the identity of the
identified resource is determined by the authoritative representations
that are or might be transmitted, or that it must be such that those
representations are correct. Then there would be no way for the two to
get out of sync in the way I suggest. But I don't think that's what
you mean, either.

I checked for "representation of" throughout part 2 and didn't find
any other difficulties with the use of this expression, so whatever
fix you choose is likely to be quite localized. Part 1 seems OK. The
single use in part 6 would need to be scrutinized. I didn't check the
other parts or other phrases.

Best
Jonathan
Received on Tuesday, 7 February 2012 15:13:03 GMT

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