How do you show up the maintenance message while you want to re-deploy a war file?

Question

Hey guys I am trying to display a maintenance message on my web page while I wanna deploy an updated war, so the original war must go offline first and at the same time, client will get 404 not found error page...My question is, what is the most common way for website maintenance? Thanks!

PS: I am not specifying which server is being used, so it could be tomcat, jboss, websphere and etc.

Answer 1

Ideally, you'll want some kind of hot-deployment support so that your users won't ever notice a service interruption. Common methods of achieving this are:

• Having multiple instances of the web application behind some kind of load balancer which directs incoming requests to a running instance. If you'd perform a deployment, you wouldn't take all instances offline at once, but sequentially take one instance offline, redeploy, restart, and repeat this sequentially for all other instances.

• Code-based hot-swapping while the software is running. The Oracle's JVM has limited support for this (HowSwap). A popular commercial tool which enables redeployments (using more sophisticated mechanisms than HotSwap) of Java web apps is LiveRebel.