so after many researchs I decide to use JBoss AS 7 configured as a load balanced cluster to get there.
so the load balancer can't be a single point of failure
Yes, so you do need to cluster load balancers as well.
It is possible to distribute the load balancing across the cluster nodes ?
In such architecture you would need to deploy a loadbalancer on everynode as well.
Even though this is doable I would rather have dedicated machines in front of the cluster. So that the cluster is isolated from the outside and only requests via Apache and AJP get all the way to the cluster.
Windows Network Load Balancer, who uses a virtual IP to get the external requests
No idea what that is, but its probably solves the problem above ^ by having each machine have private and public interfaces where JBoss AS is only visible on the private. Yes, this is douable as well, but its more matter of the OS level configuration rather than JBoss (you just need to bind jboss to the correct address).