This example is going to use the flex application created in the Linux Macromedia Flex on Tomcat-HOWTO, but you can use any web application you choose.
Edit the httpd.conf file, found in /etc/httpd/conf/httpd.conf
Uncomment the line <IfModule mod_proxy.c> and the following </IfModule>
Within the IfModule directive add the following lines:
ProxyPass /flex/ http://127.0.0.1:8081/flex/ ProxyPassReverse /flex/ http://127.0.0.1:8081/flex/
Edit the Tomcat server.xml file, found in $CATALINA_HOME/conf/server.xml, which with my install is /usr/java/tomcat/conf/server.xml
After the entry for the default connector, <Connector port="8080" ... > add the following line (replacing [fully qualified domain name] with your actual domain name or IP address):
<Connector port="8081" proxyPort="80" proxyName="[fully qualified domain name]" />
Restart Tomcat first, then Apache, and then browse to http://localhost/flex/ and Apache will pass the request to Tomcat.