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From "George Sexton" <geor...@mhsoftware.com>
Subject RE: Compression and SSL
Date Mon, 02 Nov 2009 19:11:18 GMT
> -----Original Message-----
> From: Pid [mailto:pid@pidster.com]
> Sent: Monday, November 02, 2009 11:12 AM
> To: Tomcat Users List
> Subject: Re: Compression and SSL
> 
> On 02/11/2009 16:48, Jeffrey Janner wrote:
> > OK, another newbie-ish question here.
> >
> >
> >
> > I am using Tomcat 5.5.x with APR/native libraries on Windows 2003 x32
> or
> > Windows 2008 x64 to serve applications from the US to Asia-based
> > clients.
> >
> > We encrypt everything using SSL, from Login page onward, with
> > <transport-guarantee>  of CONFIDENTIAL.
> >
> > All URLs are configured as relative, i.e., "/images/picture.png",
> > "/APP1?param1=value....", etc.
> >
> > We use Tomcat as the web server with no intervening proxies,
> > load-balancers, accelerators, etc.
> >
> > Response time is noticeably slow (based on complaint level) and I am
> > looking for ways to improve it.
> 
> Bigger server?
> 
> > Will setting the HTTPS connector "compression=on" actually compress
> the
> > data for HTTPS?
> 
> What makes you think that compressing things is going to improve
> matters?  Doing the compression is an overhead itself.
> 

In general, Compressing HTML can help a great deal for any case besides a
local network.

A typical HTML page will compress by a factor of 6 or so. Compressing a 42 K
page can result in a 7K page. This reduces the typical packet count from 28
or so to around 5. 

Even with the overhead of compressing the HTML on the server, and
decompressing it, this can yield a great performance improvement for any
user. If there are fewer packets, there are fewer lost packets.
Additionally, you're reducing the overhead of sending the packets through
the OS.

If you're serving a great deal of data, through a pipe of a fixed size, this
effectively makes your pipe 6 times bigger (assuming it's mostly HTML you
move). So, your pipe isn't as full, and you're not paying for as much
bandwidth.


So, compression of HTML is a really valid technique that will be helpful for
any case beyond the local network. The one caveat is the compressability of
the data. For example, you're not going to get much improvement attempting
to compress JPG images.


George Sexton
MH Software, Inc.
http://www.mhsoftware.com/
Voice: 303 438 9585


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