J2EE, how to let users know, that application is down

[Jiri Nejedly]

We have a J2EE application for several hundreds of users. From time to time we need to deploy new version or do some service tasks. Does exist any technique to let the users know, that the application is currently down? When users try to enter application via .../index.do, it should redirect them to some static page announcing 'Application under repair'. But how to do that, if application is undeployed or OC4J is stopped? We use OAS 10.1.3.
Thanks in advance for any ideas.

[Jeanne Boyarsky]

One approach is to have a web server do it. The web server needs to be configured between the user and the application server. Another approach is to have multiple application server clones and restart them one at a time.

[Vinoth Thirunavukarasu]

Also we can configure the static page in your web.xml like below

  <error-page>
    	<error-code>500</error-code>
	    <location>/staticErrorPage.jsp</location>
    </error-page>