- From: Julian Reschke <julian.reschke@gmx.de>
- Date: Tue, 17 Feb 2015 15:56:39 +0100
- To: "Henry S. Thompson" <ht@inf.ed.ac.uk>
- CC: "Eric J. Bowman" <eric@bisonsystems.net>, Mark Nottingham <mnot@mnot.net>, Noah Mendelsohn <nrm@arcanedomain.com>, "www-tag@w3.org List" <www-tag@w3.org>
On 2015-02-17 14:48, Henry S. Thompson wrote: > Julian Reschke writes: > >> AFAIU, this is just a misunderstanding. I recommend reading the whole >> thread, in particular >> <https://lists.w3.org/Archives/Public/ietf-http-wg/2013OctDec/0531.html>. > > I don't see that anything I said is compromised by what you wrote > there, i.e. > > Reactive conneg isn't just about 300s and 406s. Another example > would be a representation returned with a 200 response that contains > links to alternate versions of the content. > > As I made clear in what I wrote, all I have is lack of evidence _for_ > reactive conneg. What you describe above is not actually part of the > HTTP _protocol_ at all -- it amounts to an observation that 200 > content may be interpretable by human beings to offer multiple choices It doesn't have to be a human being. Link relations have been mentioned elsewhere. > for follow-up. I also think that the following is ingenuous at best: > > If the user agent is not satisfied by the initial _response > representation_, it can perform a GET request on one or more of the > alternative resources, selected based on metadata included in the > list, to obtain a different form of representation for that > response. Selection of alternatives might be performed automatically > by the user agent or manually by the user selecting from a generated > (possibly hypertext) menu. > > Note that the above refers to _representations of the response_, in > general, not representations of the resource. The alternative > representations are only considered representations of the target > resource if the response in which those alternatives are provided > has the semantics of being a representation of the target resource > (e.g., a 200 (OK) response to a GET request) [1] [emphasis added] > > This distinction between representations of resources and > representations of responses is, as far as a quick search of the 723* > family reveals, both unprecedented and unexplained. But that's > another topic, I guess. > > Wrt your point, I read the second paragraph from 7231 above as saying > it's _not_ conformant, supposing I ask for a document from your site, > to respond with a list of links to alternative representations of that > document in a 200 response, because a 200 response says "here is a > representation of the document you requested". So I don't see how you > could view such a response as a conformant example of reactive > conneg---it's either not conformant, or not conneg. It might be a full representation of the identified resource, *including* links to alternate versions. Think Wikipedia links to alternate language versions. Best regards, Julian
Received on Tuesday, 17 February 2015 14:57:26 UTC