On Tue, 8 Nov 2005 [EMAIL PROTECTED] wrote:
Igor Sysoev wrote
Actually, with MSIE 5.5+ appearance the chances that client can not
decompress the response from downstream cache have increased.
If MSIE 5.5 is configured to work via proxy with HTTP/1.0, then
MSIE will never send "Accept-Encoding" header, and it would refuse
the compressed content.
You are right on the first part. If you don't have the "Use HTTP/1.1
for Proxies" checkbox on then no "Accept-Encoding:" header
would be sent... ( principle of least astonishment applies here ).
...however... I think you will discover on closer inspection that
the second part is not true. Even if MSIE 5.x doesn't send an
"Accept-Encoding: gzip" header... it KNOWS it can decompress
and will do so for any response that shows up with "Content-encoding: gzip"
regardless of whether it sent an "Accept-Encoding: gzip" header.
I've just checked MSIE 6.0 configured to work via proxy with HTTP/1.0
(default settings). I've preloaded into the proxy the compressed pages using
Firefox. Then I've asked the same pages from MSIE. MSIE has showed
1) compressed pages for "/page.html" requests
2) and the "Save file" message box for the "/dir/" requests.
My mod_deflate allows optionally to add "Vary" header to compressed
response only.
So you still run the risk of only getting one variant 'stuck' in a
downstream cache. If the uncompressed version goes out at
'start of day' with no "Vary:" then the uncompressed version
can get 'stuck' where you don't want it until it actually expires.
I prefer to use compressing as safe as possible.
So the default settings of my mod_deflate and my new lightweight server
named nginx are:
1) compress "text/html" only;
2) compress HTTP/1.1 requests only;
3) do not compress responses for the proxied requests at all.
And of course, mod_deflate and nginx have many directives to change
this behavior: for example, they may compress responses for proxied
requests if responses have "Cache-Control" header with the "private",
"no-store", "no-cache" values.
Igor Sysoev
http://sysoev.ru/en/
