Application server selection and Load-balancer

Application servers support some application. You can assume we have series of Nodes having this applications running.

Node1 ....... Noden --- all under a common domain say myappsvr.com

These nodes need to be selected thru load-balancer. This is all fine until here.

These Node1..... Noden based on its capacity/resource can handle some amount of events.

What needs to be supported on the Node1,.... Noden to monitor from load-balancer side. Do we have any library from F5 which can be integrated into the application server side.