The advantages of using JMX?

I am kind of new to JMX, but could somebody elaborate the advantages of using JMX over other technologies like EJB? I have read the tutorial and concepts from Sun's website, and it seems to me that the whole concept of JMX is to wrap one application or resource as MBean, register it with JMX server, and then invoke the corresponding methods from somewhere else. However, similar steps have already been taken by EJB.

Furthermore, if the whole application is on one server, which is the most common scenario, you can easily pack the resources or sub-applications as regular Java Beans, and then use them directly without worrying about the JMX server.

Probably I am just not clear what problem JMX is trying to address.

Thanks in advance!

James