First you need to determine which runtime parameters you want to monitor, which of those you additionally want to be able to change, and what -if any- other actions you might want to execute via JMX.
I have added a few links to the
JavaEnterpriseEditionFaq. Part 2 of the developerworks introduction contains a realistic example of how to instrument an application.
Since those introductions are a bit dated,
you should also read "Using JConsole to Monitor Applications" if you are using at least
Java 5.
[ January 03, 2007: Message edited by: Ulf Dittmer ]