JMX (Java Management Extensions) is an API for exposing a management interface of a component/application/device in a standard, platform-independent way. The core of JMX are the things called MBeans. MBeans are objects that implement one of the standard javax.management.*MBean interfaces. For example, I could write an MBean implementation for an EJB which would allow tweaking certain properties of the EJB at runtime (such as the location of a file, the timeout for obtaining a connection to system X, the algorithm to use for doing foo, etc.). Start by reading the sample chapter from JMX in Action.