JMX (Java Management Extensions) Question:

Answer #1
MX is conceptually simple, yet bears the fruit of years of domain experience and research. In a nutshell, JMX defines a standard means for applications to expose management functionality
1)Instrumentation level
2)Agent level
3)Management level

Answer #2
JMX(Java Management Extension), introduced in J2SE 5.0 provides an efficient way to monitor and manage JVM resources such as threads, memory. JMX Architecture can be divided into three parts.
1. Remote Management Application.
2. JMX Agent.
3. MBean (Instrumentation level).
This is further explained in the following post.
http://www.cleantutorials.com/jconsole/jmx-java-management-extension-monitoring-and-management-in-java