On Sat, Jun 4, 2011 at 7:58 PM, Ben Noordhuis <i...@bnoordhuis.nl> wrote:
> > And I still don't understand how that relates to Vary:User-Agent. > What's > > really at issue here seems more related to proxies; is that right? That > > proxies were not respecting Accept-Encoding, but sending gzipped content > to > > browsers that did not want it? Is that still a problem? Which proxies > were > > broken? Are they still broken? > > Some popular OSS packages depend on Vary: User-Agent to make > downstream proxies (reverse or forward) do the right thing. > I'm pretty interested in deconstructing this further. Can you be more specific? Which OSS packages? Under what scenario would a proxy do the wrong thing in the absence of Vary:User-Agent (other than, obviously, when the content actually varies based on user-agent)? > And, while I understand the reluctance to help me figure out from our > module > > what values were passed to SetEnvIfNoCase and Header, I would like to see > > whether there's agreement that the Apache 2.2 docs for mod_deflate are no > > longer appropriate -- and in fact harmful. > > I've been mulling it over for 10 minutes and I can't decide. It's > harmful because it leads to a proliferation of cached objects (bad) > I think that at least some proxies would likely decide to simply *not* cache in the presence of vary:user-agent, rather than explode their caches. That makes the web slower. But, Varnish, in particular, will explode its cache: http://www.varnish-cache.org/docs/trunk/tutorial/vary.html. I believe that will also make the web slower, because the hit-rate will suffer and they'll be less room the cache for differentiated content. > but removing it from the documentation will break things for someone > somewhere (also bad). > I'm trying to get a handle on exactly what would break, and for whom :) -Josh
