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See Other vs Contents of Related, was: 2NN Contents Of Related (303 Shortcut)

From: Julian Reschke <julian.reschke@gmx.de>
Date: Fri, 05 Sep 2014 09:47:53 +0200
Message-ID: <54096AA9.6070203@gmx.de>
To: Sandro Hawke <sandro@w3.org>, "Roy T. Fielding" <fielding@gbiv.com>
CC: Martin Thomson <martin.thomson@gmail.com>, Eric Prud'hommeaux <eric@w3.org>, Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
On 2014-09-05 05:18, Sandro Hawke wrote:
> ...
> See: http://tools.ietf.org/html/draft-prudhommeaux-http-status-2nn-00
>
>>      implies that we don't have a representation of A, but we know
>> what you
>>      really wanted (better than you) so here is a representation of B.
>
> If I understand right, your "better than you" comment is about how there
> might already be a cache of B, and with 2NN that cached copy wont be
> used.  I agree that's a weakness in this proposal, although in all the
> scenarios I've seen discussed, it's unlikely B would be cached unless
> the 2NN response to A also was, so this weakness wouldn't be observed in
> practice.

Why wouldn't the response to the redirect GET (303 -> 200) not be cached?

>> Now, here's the problem:
>>
>> "It's a round trip short cut!"  No, because it won't be cached.
>
> As above, in the scenarios we're looking at, it's unlikely B will be
> cached unless the 2NN response for A is also.
>
>> 303 round trips to the same server are almost entirely free in HTTP/1.1
>> because of persistent connections,
>
> Free of connection setup overhead, but they still cost a second
> round-trip delay.
>
> In LDP applications, these calls are more like RPC than like displaying
> a web-page, so milliseconds might possibly count more than they do in
> more common existing applications.
> ...

It that's the problem, have you considered to tweak 303 to actually 
return the representation of the "other" resource (using a new Prefer 
option?)?

GET / HTTP/1.1
Prefer: contents-of-related

HTTP/1.1 303 SEE OTHER
Location: /other
Preference-Applied: contents-of-related
...

(representation of /other)

?

Best regards, Julian
Received on Friday, 5 September 2014 07:48:32 UTC

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