- From: Julian Reschke <julian.reschke@gmx.de>
- Date: Tue, 17 Feb 2015 13:41:58 +0100
- To: "Henry S. Thompson" <ht@inf.ed.ac.uk>, "Eric J. Bowman" <eric@bisonsystems.net>
- CC: Mark Nottingham <mnot@mnot.net>, Noah Mendelsohn <nrm@arcanedomain.com>, "www-tag@w3.org List" <www-tag@w3.org>
On 2015-02-17 13:11, Henry S. Thompson wrote: > Eric J. Bowman wrote, back on 19 December [sorry for slow reply!]: > >> Henry S. Thompson wrote: >>> >>> Some non-anecdotal evidence, albeit still subject to varying >>> interpretations, is available in a talk summarising my analysis of >>> two sets of cache-logs, from June 2013 and June 2014: >>> >>> http://www.ltg.ed.ac.uk/~ht/HST_noREST.pdf >>> >>> Start at slide 13 and stop after slide 15 if you're not interested in >>> my critique of REST, but just want to see the numbers. >>> >> ... >> Except the conneg stuff. Are you really saying nobody compresses HTTP >> payloads on the wire? Because that's a real-world instance of conneg I >> highly doubt nobody uses. Personally, I cache compressed content and >> unzip it on the fly, to save CPU on the Celerons driving the budget >> webhosting world, which finally got around to Vx and threading but still >> aren't up to the task of ubiquitous HTTPS any more than the SPARC T1. >> >> What forms of conneg were you looking for, but apparently didn't find? > > The Squid logs which is what I was working with don't contain any > request or response headers, just the response status code. The only > evidence available of what 2616 [1] calls "server-driven negotiation" > and 7231 calls "proactive negotiation" is a 406 (Not Acceptable) > response, indicating that the server has no representation satisfying > the Accept... headers in a request. I found only a handful of 406 > responses, none of which appeared to be actually responding to an > attempt at conneg. Note that this kind of conneg is what I think most > people, including you, understand by "content negotiation" -- it's > certainly what the TAG's _WebArch_ [3] and _Alternative > Representations_ [4] are discussing. Somewhat surprisingly (to me at > least), it's also clearly recommended _against_ by 2616 and 7231. > > What they _recommend_ is what 2616 calls "agent-driven" [5] and 7231 > "reactive" [6] conneg. This involves a server responding to a GET > with a 300 Multiple Choices response, from which a user agent then > selects, either automatically or by reference to a human. Presence of > 300 responses in the log would then constitute unequivocal evidence of > "reactive" conneg. But in fact what there is turns out to actually be > evidence _against_ (conformant) conneg. _All_ the examples in the log > were generated by Apache's mod_speling [sic] module, offering "common > basename", "character missing" or "mistyped character" hypotheses > about failures to find a requested URI. > ... 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>. Best regards, Julian
Received on Tuesday, 17 February 2015 12:42:53 UTC