Antwort: Re: [Mod_gzip] Gzip encoding, IE 5 & 6, proxy caches, NetCache

[mod_gzip@lists.over.net]

Hi Kieran,


> Now, I've done some investigation, and it appears that - furthermore -
> as far as IE6 is concerned, this problem only manifests itself when the
> browser is using a proxy (either transparently, or explicitly).
> In particular, the NetCache proxy (although possibly with others).

But how can a browser "use" a transparent proxy?
If the proxy is transparent, then the browser isn't even
aware of the proxy's existance.

> I'm running IE6 with version 6.x of urlmon.dll, and am still experiencing
> the problem.
> So, based on my current evidence, a minimal set of criteria that will
> cause gzip encoded responses to be corrupted are:
> 1. Run a windows-based machine
> 2. Run IE5 or IE6
> 3. Have RealDownload installed (or some other application
> that writes keys to the following location in the registry:
> HKEY_CLASSES_ROOT\Protocols\Name-Space Handler)
> 4. Use a proxy server, either:
> Implicitly (ie, your ISP has a transparent proxy)
> Explicitly (ie, you have set up a IE's options to use a proxy) (*)

I think I am doing all of the above, even using gzip_cnc as source
for compressed content (not mod_gzip).
- I am running M$IE 6.0 on WinNT4,
- I am using some Netscape proxy server to connect to the WWW, and
- HKEY_CLASSES_ROOT\Protocols\Name-Space Handler at least contains
  an entry named "mk", containing the value
  "Standard" -> "NameSpace Filter for MK:@MSITStore:...".
(Which I don't know where it comes from, I am not aware of any "MK"
product running on this PC.)

> The above criteria will lead to webpages being predictably currupted,

Not in my case ... :-(

> However, one *big* factor, that occurs time and time again, is that IE
> (5 & 6) appear to specifically dislike dealing with gzip-encoded,
> > chunked content served via the (very common) "NetCache" web-proxy
> > (http://www.netapp.com/products/netcache/).

Ah! Now I recognize the combination of "gzipped" and "chunked"!

And I remember that mod_gzip is explicitly de-chunking content
before daring to compress it because of known bugs in current
browsers! Therefore, I most likely cannot reproduce the problem
with mod_gzip or gzip_cnc.
You would have to offer your compressing site for experiments -
and I would suggest to rather _not_ compress chunked content.
   (http://www.schroepl.net/projekte/mod_gzip/config.htm#transfer_encoding)

> All experiments I have conducted *have* worked with Netscape 6.2, and
> Mozilla, which would tend to suggest to me that this is an Internet
> Explorer bug.

I tend to agree, but this won't really help you ... did you check
Opera 6 and Netscape 4 too?



Regards, Michael