Load Balancing Batons provide a conceptually simple way to implement internal load balancing for arbitrary tasks. A LoadBalancer is configured with a pool of batons that may be checked out by threads. When a baton is checked out, the calling thread has the right to perform the operation associated with the baton. When finished, it returns the baton to the LoadBalancer's pool of batons so that other threads may now perform the task.

For example, if one of the resource-intensive tasks your agent performs is to respond to SIF_Requests for "all students", create a LoadBalancer instance to represent this task. Whenever a SIF_Request is received for "all students", obtain a Baton from the LoadBalancer. If the baton is received, you may carry out the task at hand by querying the database for all students and returning those students as StudentPersonal objects. If the baton is not received in the timeout period, throw a SIFException with category 10 ("Transport Error"), which instructs the ZIS to keep the message in the agent's queue for later retry.

When an agent is unable to obtain a Baton in response to a SIF_Request, it should put the agent to sleep until the load has relaxed. The LoadBalancer class offers a simple way to achieve this. When requesting a Baton times out, call the Zone.sleep method to put the agent to sleep. Next, register a LoadBalancerListener with the LoadBalancer. When the LoadBalancer has a free pool of available batons greater than 1, it will call your listener's onBatonsAvailable method. You can then call Zone.wakeup to wakeup the agent, signaling the ZIS that it may continue sending messages.