How can i do zero down time deployment on cluster environment?

I need to deploy a major deployment on my system (more that 15 ear file ) , my system is high available system , So how can I do this deployment with zero downtime ? my application server is IBM-WAS

After updating the applications, you can utilize the "Rollout Update" feature. Rather than saving and synchronizing the nodes after updating, you can use this feature which automatically performs the following tasks to enable the changes to propagate to all deployment targets while maintaining high availability (assuming you have a horizontal cluster, such that cluster members exist on multiple nodes):

1. Save session changes to the master configuration
2. For each node in the cluster (one at a time, to enable continuous availability):
   1. Stop the cluster members on the node
   2. Synchronize the node
   3. Start the application servers (which automatically starts the application)