RE: XCompress for ISA -- Compression Filter
- From: "Wayne Berry" <wayne@xxxxxxxxxx>
- To: "'[ISAserver.org Discussion List]'" <isalist@xxxxxxxxxxxxx>
- Date: Fri, 9 Jul 2004 13:37:23 -0700
John,
Last Question First:
Q: My understanding of HTTP compression is it must be done on 2 ends to be
workable.
A: Ok, here is how this works, In HTTP 1.1 there is a standard for
compressing HTTP responses. Basically, the browser says: "I accepted
encoding, give me an encoded page if you can". It does this by sending an
"Accept-Encoding: gzip" HTTP request header. Gzip is the type of encoding
it will accept. It also request encoding called deflate -- they are both
very simliar. When the server gets this it can deciede to compress the
response or not. If it does compress it, it sends a response header like
this "Content-Encoding: gzip". When the browser recieves this response
header it it knows that the page in compressed (looks like binary garbage in
your TCP/IP trace), the browser then decompresses the response and renders
the uncompressed page. With gzip/deflate you can get a 80% reduction in
your page, making it faster on latent networks and saving you bandwith
costs. So the answer is the browser knows how to decompress all you have to
do is provide compression. With the XCompress for ISA, compression is done
on the ISA server by our filter.
Q: What is the purpose/benefit of compressing at the firewall?
A: Well firewall compression might not be that interesting, unless you are
using your ISA server for a reverse proxy or forward proxy.
Let's say your ISA is set up as a proxy server for the outbound Internet at
your Coporate headquarters in New York, and you have a WAN where your branch
office is in LA. The branch office connects via a partial frame via VPN to
coporate that provides outbound access. If you install XCompress for IIS in
NY, it will compress all the Internet responses from the outside, making the
partial frame faster, and the VPN encryption quicker.
Or, you have a ISA server in front of your web server, as a
firewall/proxy/cache, and you want to compress that traffic before it leaves
your data center. Install XCompress for IIS, and the outbound traffic is
reduced and your bandwidth bills goes down.
Q: How will that speed up traffic or reduce bandwidth usage?
A: Is this question answer by the above?
-Wayne
-----Original Message-----
From: John Tolmachoff (Lists) [mailto:johnlist@xxxxxxxxxxxxxxxxxxx]
Sent: Friday, July 09, 2004 1:24 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: XCompress for ISA -- Compression Filter
http://www.ISAserver.org
Replying to list for discussion purposes.
What is the purpose/benefit of compressing at the firewall? How will that
speed up traffic or reduce bandwidth usage? My understanding of HTTP
compression is it must be done on 2 ends to be workable.
John Tolmachoff
Engineer/Consultant/Owner
eServices For You
> -----Original Message-----
> From: Wayne Berry [mailto:wayne@xxxxxxxxxx]
> Sent: Friday, July 09, 2004 1:12 PM
> To: [ISAserver.org Discussion List]
> Subject: [isalist] XCompress for ISA -- Compression Filter
>
> http://www.ISAserver.org
>
> ISAList:
>
> I will take just a second to blow my own horn and try to get some Beta
> Testers. We (XCache Technologies) have developed an ISA filter that
> performs HTTP compression on traffic going through the ISA server in
> both directions.
>
> Basically, HTTP compression is what Google and a bunch of other
> companies are using to speed their pages and decrease their bandwidth
> and it doesn't require any client side code -- the browsers know how
> to decompress since
it
> is part of the HTTP 1.1 standard.
>
> I am looking for a few Beta testers that would like to try the
> product, we have developed in conjuction with Microsoft and they are
> testing it
already
> for us. Just write me off the list.
>
> Kind Regards,
> Wayne Berry
> Developer
> XCache Tech
> http://www.xcache.com
>
>
>
>
>
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