As an example, this app (Apache Helix) implements MBeans, which means that you can connect to the running application to observe its state and manage it. You ca

As an example, this app (Apache Helix) implements MBeans, which means that you can connect to the running application to observe its state and manage it. You can do this with the standard JMX toolchain, without having to implement anything else in the app other than the MBeans. I realize, writing this, that for someone unfamiliar with the ecosystem this sounds very abstract, but MBeans (managed beans) are simply counters, operations, stats, faults that the app makes available to other apps/users via a standard protocol.