Mailing-List: contact users-help@httpd.apache.org; run by ezmlm
Precedence: bulk
Reply-To: users@httpd.apache.org
Received-SPF: neutral (athena.apache.org: local policy)
From: Rainer Sabelka <sabelka@iue.tuwien.ac.at>
To: users@httpd.apache.org
Date: Tue, 24 Jun 2008 12:05:03 +0200
User-Agent: KMail/1.9.51 (KDE/4.0.4; ; )
References: <200806231907.56381.sabelka@iue.tuwien.ac.at>
 <4860A0C7.60204@ice-sa.com>
In-Reply-To: <4860A0C7.60204@ice-sa.com>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
Message-Id: <200806241205.04134.sabelka@iue.tuwien.ac.at>
Subject: Re: [users@httpd] Use Apache for compression offloading

On Tuesday 24 June 2008 09:22:47 Andr=E9 Warnier wrote:
> Hi.
>
> I'm not a specialist of that kind of thing, but I'm curious and I just
> wonder about the following kind of scenario :
>
> - In the proxy server, unset the Accept-encoding header, but set another
> non-standard one (or an environment value) that will not be recognised
> by the back-end server
> - condition the SetOutputFilter DEFLATE by this other header/value
> - do the proxying.

Hm. I think the check for the Accept-encoding header is hard-coded in=20
mod_deflate. No matter if I SetOutputFilter DEFLATE conditionally or=20
unconditionally, the filter won't compress the output as soon as I unset th=
e=20
Accept-encoding header.

> The back-end server will not get the Accept-encoding
> header.  Instead it will get the new header you set, but will not react
> to it, so not do compression.
> - but the front-end server still will

> I think that mod_sentenvif and/or mod_rewrite should allow you to do the
> above.  Someone else would have to give you the specifics though.
>
> Andr=E9
>
> Rainer Sabelka wrote:
> > Hi,
> >
> > I try to use apache (version 2.2.8 on Ubuntu 8.04) for compression
> > offloading. What I want to do:
> > - use mod_proxy to forward all requests to the application server
> > - use mod_deflate to compress the output
> > - remove the "Accept-Encondig:" header from the client's request before
> > sending it to the application server to avoid that the compression is
> > done there.
> >
> > My frist approach didn't work:
> >
> > <VirtualHost *:80>
> >     ServerName www.example.com
> >     <Proxy *>
> >          Order deny,allow
> >          Allow from all
> >     </Proxy>
> >     ProxyRequests Off
> >     ProxyPass / http://realserver:80/
> >     ProxyPreserveHost on
> >     RequestHeader unset Accept-Encoding
> >     SetOutputFilter DEFLATE
> > </VirtualHost>
> >
> > The problem with this approach: when I use "RequestHeader unset Accept-
> > Encoding" then the application server gives me uncompressed output (goo=
d)
> > but also mod_deflate won't comress the output (bad).
> >
> > So, this is my second approch, which actually works, but I think is a b=
it
> > an over-kill:
> >
> > <VirtualHost *:80>
> >     ServerName www.example.com
> >     <Proxy *>
> >          Order deny,allow
> >          Allow from all
> >     </Proxy>
> >     ProxyRequests Off
> >     ProxyPass / http://localhost:8000/
> >     ProxyPreserveHost on
> >     RequestHeader unset Accept-Encoding
> >     SetOutputFilter DEFLATE
> > </VirtualHost>
> >
> > <VirtualHost localhost:8000>
> >     ServerName www.example.com
> >     <Proxy *>
> >          Order deny,allow
> >          Allow from all
> >     </Proxy>
> >     ProxyRequests Off
> >     ProxyPass / http://realserver:80/
> >     ProxyPreserveHost on
> >     RequestHeader unset Accept-Encoding
> > </VirtualHost>
> >
> > Here I have 2 instances of apache in proxy-mode connected in series. The
> > first one forwards the request to the second one and does the compressi=
on
> > of the output. The second instance just removes the Accept-Encoding
> > header before it forwards the request to the application server.
> >
> > But I think there must be a an easier solution. Has any body an idea how
> > to get this working with only a single instance of apache?
> >
> > Thanks,
> > -Rainer
> >
> > ---------------------------------------------------------------------
> > The official User-To-User support forum of the Apache HTTP Server
> > Project. See <URL:http://httpd.apache.org/userslist.html> for more info.
> > To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
> >    "   from the digest: users-digest-unsubscribe@httpd.apache.org
> > For additional commands, e-mail: users-help@httpd.apache.org
>
> ---------------------------------------------------------------------
> The official User-To-User support forum of the Apache HTTP Server Project.
> See <URL:http://httpd.apache.org/userslist.html> for more info.
> To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
>    "   from the digest: users-digest-unsubscribe@httpd.apache.org
> For additional commands, e-mail: users-help@httpd.apache.org


---------------------------------------------------------------------
The official User-To-User support forum of the Apache HTTP Server Project.
See <URL:http://httpd.apache.org/userslist.html> for more info.
To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
   "   from the digest: users-digest-unsubscribe@httpd.apache.org
For additional commands, e-mail: users-help@httpd.apache.org