how to deploy an app on glassfish without without crashing the service?

I have an app that ta开发者_如何学编程ke long time to deploy/redeploy because this use EJB3, JPA2, JSF, Icefaces

The app is deployed on glassfish 3 on ec2 in amazon web services. Each i redeploy the app, while is redeploying the app, the service isn't available.

How can i redeploy an existing application and still the service available, until the redeploy finish?

thanks in advance

---

Depending on your architecture, you will always lose the service for a few seconds whilst you redeploy.

The proper way to architect this would be to have a software load balancer sitting in front of 2 or more glassfish server instances which are set in a cluster. The load balancer will automatically route all requests to the server holding the older available service. Once the new service is up and running, it will route requests there again. Using mod_jk inside apache works well as the load balancer.