[users@httpd] mod_deflate questions

[Chris Price <cp...@its.to>]

	Hey all;

	I have some questions about mod_deflate;

	Specifically, in my 8 years of using apache, I had never heard of it 
until a few weeks ago. Google shows plenty of howto implement and man 
page sites, but few 'mod_deflate is soo good it saved my marriage' type 
of testimonials. Given the significant savings in bandwidth that *seem* 
to go with mod_deflate I am wondering why I have never heard of it - it 
seems too good to be true.

	Would someone please be so kind as to post a broef summary of strengths 
and weaknesses of mod_deflate? Browser incompatibility, issues with 
nat/proxies, etc... My spidey sense is telling me that something isnt 
quite right here...

	Cheers and TIA,
	
	Chris

---------------------------------------------------------------------
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

Re: [users@httpd] mod_deflate questions

[Chris Price <cp...@its.to>]

	
	Once again my many thanks to Joshua for providing concise and extremely 
informative responses on this list.

Joshua; Its people like you that make open-source communities *work*.	

	Cheers from Calgary,

	Chris Price


> Plenty of people use mod_deflate (and the older mod_gzip), so there
> isn't any big catch.  It does indeed significantly reduce bandwidth
> usage and sometimes latency.
> 
> There are some disadvantages:
> - Browser incompatibilities.  The mod_deflate docs give instructions
> on how to work-around the most common ones.
> 
> - Increased processor usage.  But many webservers are not processor 
> constrained.
> 
> - Pages become less cacheable since you need to vary on at least
> accept-encoding, and frequently user-agent as well.
> 
> - You can't use zero-copy techniques (liek the sendfile syscall ) to
> send files, which increases the load on the server.
> 
> - For many sites, the majority of content is already-compressed stuff
> like images, which won't be helped by mod_deflate.
> 
> Joshua.


---------------------------------------------------------------------
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

Re: [users@httpd] mod_deflate questions

[Joshua Slive <jo...@slive.ca>]

On 8/23/06, Chris Price <cp...@its.to> wrote:
>
>
>         Hey all;
>
>         I have some questions about mod_deflate;
>
>         Specifically, in my 8 years of using apache, I had never heard of it
> until a few weeks ago. Google shows plenty of howto implement and man
> page sites, but few 'mod_deflate is soo good it saved my marriage' type
> of testimonials. Given the significant savings in bandwidth that *seem*
> to go with mod_deflate I am wondering why I have never heard of it - it
> seems too good to be true.
>
>         Would someone please be so kind as to post a broef summary of strengths
> and weaknesses of mod_deflate? Browser incompatibility, issues with
> nat/proxies, etc... My spidey sense is telling me that something isnt
> quite right here...

Plenty of people use mod_deflate (and the older mod_gzip), so there
isn't any big catch.  It does indeed significantly reduce bandwidth
usage and sometimes latency.

There are some disadvantages:
- Browser incompatibilities.  The mod_deflate docs give instructions
on how to work-around the most common ones.

- Increased processor usage.  But many webservers are not processor constrained.

- Pages become less cacheable since you need to vary on at least
accept-encoding, and frequently user-agent as well.

- You can't use zero-copy techniques (liek the sendfile syscall ) to
send files, which increases the load on the server.

- For many sites, the majority of content is already-compressed stuff
like images, which won't be helped by mod_deflate.

Joshua.

---------------------------------------------------------------------
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