[Mod_gzip] About 'Vary' header insertion

[saravana kumar]

Hello,

I currently installed mod_gzip/mod_ssl over apache.  I looked through this 
mailing list to get to know about the mod_gzip information.

I was trying the 'vary' header insertion for mod_gzipped response.  I went 
through the 'vary' header discussion in this mailing list and I found there 
are two alternate.

1. no cache, by adding Cache-Control: private & Pragma: no-cache to the 
response, will make sure both HTTP/1.1 & HTTP/1.0 cache will not cache this 
content.
2. Adding 'Vary: user-agent, Accept-Encoding' header to it, so that if any 
caches if they capable, they server the gzipped content correctly based on 
the user-agent/Accept-Encoding.  Now, the problem, what if the cache does 
not know about Vary header and discards the header?. Will it end up caching 
the content?.

I tried the first method. And the caches(squid in my case) are not caching 
this responses.  But when I use <BACK/FORWARD> button in Netscape 4.7, it 
re-fetches the page instead of display the previously fetched page and 
sometime it displays 'Data not found' error.  So, that tells me that 
Netscape browser didn't cache the response to the history. It happens once a 
while with IE 6.0 also and the error message it displays 'Page has expired'.

Now, whats the safer method, to make sure the browser receives compressed 
response without any hiccups if there are some shared caches on the way.

Thanks in advance,
-Sara,


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