so how i did this was to have a two servers a webserver and appserver
webserver was pointed to app server - below steps should help i guess :)
This procedure describes how you can put a Pega instance (and the PRD instance in particular) into Maintenance Mode and back into regular production mode. This involves making the JBoss unavailable for regular users and bringing up a "Maintainance page".
Step 1) Make Plan
Define the details of the outage (start, duration , reason) because you need to know what to put on the Sorry Page
Define the list of systems/instances involved.
This Procedure assumes you are using the current PRD JBoss instance and the Apache instance on the same server.
Step 2) Define Maintainence Message
create a html file with sorry message index.html file in /apache/htdocs
Step 3) Stop JBoss
Bring the Jboss down as usual.
You should get a "success" status.
Do a process check "ps -ef | grep jboss" to make sure that no jboss is running before continue with the next step.
Step 4) Reconfigure Apache
Stop the Apache server
run command ./apache_stop.sh
Open the httpd.conf file in /apache/conf
Command : vi httpd.conf then enter ‘i’ and comment your existing port XXX.XX.XX.XX:8090and add a new port Listen XXX.XX.XX.XX:8080
add a statement
where XXX.XX.XX.XX:8080 is the current IP/port of you application
in our case listen to 8080.
command to save : enter escape :wq
Step 5) Restart the Apache
Restart the Apache and check the sorry page is shown under the production link
Step 6) Reconfigure JBoss
a) command : vi standalone-full.xml enter ‘i’ and make your changes