Don't forget the ongoing issue that if you ONLY vary on 'Accept-Encoding'
then almost ALL browsers will then refuse to cache a response entity LOCALLY
and the pain factor moves directly to the Proxy/Content Server(s).
If you vary on 'User-Agent' ( No longer reasonable because of the abuse
of that header 'out there'? ) then the browsers WILL cache responses
locally and the pain is reduced at the Proxy/Content server level, but
pie is not free at a truck stop and there are then OTHER issues to deal with.
The OTHER 'ongoing issue' regarding compression is that, to this day,
it still ONLY works for a limited set of MIME types. The 'Accept-Encoding:
gzip,deflate'
header coming from ALL major browser is still mostly a LIE. It would seem
to indicate that the MIME type doesn't matter and it will 'decode' for ANY
MIME type but nothing could be further from the truth. There is no browser on
the
planet that will 'Accept-Encoding' for ANY/ALL mime type(s).
If you are going to turn compression ON by default, without the user having to
make any decisions for their particular environment, then part of the decision
for the default config has to be 'Which MIME types?' text/plain and/or
text/html only? SOME browsers can 'Accept-Encoding' on the ever-increasing
.js Javascript backloads but some CANNOT.
These 2 issues alone are probably enough to justify keeping compression
OFF by default. A lot of people that use Apache won't even be able to get
their heads around either one of these 'issues' and they really SHOULD
do a little homework before turning it ON.
Someone already quoted that...
'people expect the default config to just WORK without major issues'.
That's exactly what you have now.
It's not 'broken'.
Why change it?
Kevin Kiley
-----Original Message-----
From: Sergey Chernyshev <sergey.chernys...@gmail.com>
To: dev@httpd.apache.org
Sent: Tue, Jun 1, 2010 3:09 pm
Subject: Re: canned deflate conf in manual -- time to drop the NS4/vary?
Yeah, it should only Vary on Accept-encoding (already does). It's still not
perfect, but at least it doesn't blow up proxies too much.
The question to people with statistics - are there any other issues with
gzip/proxy configurations?
Sergey
On Tue, Jun 1, 2010 at 11:01 AM, Eric Covener <cove...@gmail.com> wrote:
IIUC, the vary: user-agent to accomodate Netscape 4 is a pain for
caches because obviously they can only vary on the entire user-agent.
http://httpd.apache.org/docs/2.2/mod/mod_deflate.html
Is it time to move this aspect of the snippet into a separate note or
some historical trivia section, to remove the Vary?
--
On the same topic, are there still non-academic CSS and JS compression
issues (e.g. XP-era browsers, earlier, later, ???) Should we instead
account for these in the "complicated/more compression" example, and
is there a way to do so without adding the Vary right back in?
--
Eric Covener
cove...@gmail.com
