Jul 122011
 Posted by on July 12, 2011 at 6:20 pm IBM HTTP Server, IBM Websphere Tagged with: ,  Add comments

To enable web compression, we need to create a mod_deflate.conf file and also do some changes to the web server configuration – httpd.conf file.

To create the mode_deflate.config, perform the following operations:
1.    Create mod_deflate.conf file. The contents of the file are provided below:

<Location />
# Insert filter
#Comment SetOutputFilter and
#uncomment AddOutputFilterByType to disable js files compression
SetOutputFilter DEFLATE
#AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css

# Netscape 4.x has some problems...
BrowserMatch ^Mozilla/4 gzip-only-text/html

# Netscape 4.06-4.08 have some more problems
BrowserMatch ^Mozilla/4\.0[678] no-gzip

# MSIE masquerades as Netscape, but it is fine
# BrowserMatch \bMSIE !no-gzip !gzip-only-text/html

# NOTE: Due to a bug in mod_setenvif up to Apache 2.0.48
# the above regex won't work. You can use the following
# workaround to get the desired effect:
BrowserMatch \bMSI[E] !no-gzip !gzip-only-text/html

# Don't compress images
SetEnvIfNoCase Request_URI \
\.(?:gif|jpe?g|png)$ no-gzip dont-vary

# Make sure proxies don't deliver the wrong content
Header append Vary User-Agent env=!dont-vary


DeflateFilterNote Input instream
DeflateFilterNote Output outstream
DeflateFilterNote Ratio ratio

#If <VirtualHost> defined then add below log config in <VirtualHost>
#Othewise uncomment here to enable deflate log
#CustomLog /opt/Apache/logs/deflate.log \
#          '"%r" %{outstream}n/%{instream}n (%{ratio}n%%)'

2.    If VirtualHost defined then add the log directive in that section. For secure web server add the following after ssl_request_log definition.

CustomLog /opt/Apache/logs/deflate.log \
'"%r" %{outstream}n/%{instream}n (%{ratio}n%%)'

This step is optional and can be skipped.
Change the path to the log file as per your server setup.

3.    Save and close mod_deflate.conf file.
4.    Check the ownership for the file mod_deflate.conf, the web server admin should have rights for this file; change ownership if required.
5.    Restart web server.

Modify The Web Server Configuration For Web Compression

To modify the Web Server configuration file, open the file httpd.conf in the ‘<HTTPSERVER_ROOT>/conf’ directory in a simple text editor, like vi or notepad, and perform the following operations:
Uncomment headers_module loading line in the httpd.conf to enable the server to start:

LoadModule headers_module modules/mod_headers.so

Add the following in httpd.conf after the last LoadModule directive.

LoadModule deflate_module modules/mod_deflate.so
Include conf/mod_deflate.conf

 The path for mod_deflate.conf is from the web server root; modify it as per your server setup
Save and close httpd.conf file.

To check syntax use

apachectl -t

in APACHE_HOME/bin folder.

Repeat the stepsfor all the web servers in the web server cluster. Once above changes are done restart HTTP Servers to make the changes take effect.


A Middleware Consultant, skilled in project implementation of J2EE Applications on Application Servers like WebSphere, WebLogic, JBoss and Tomcat, etc. My job includes Infrastructure Planning, Design, Administrative Developments, support, Installation, Configuration, Failover, High Availability, Performance Monitoring/Tuning, Analyzing and Debugging server/application/platform issues.

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