Java Reference
In-Depth Information
Figure 1.5
Up-close view of an
MBean interacting
with the resource it
manages
If you desire, you can even create an MBean that presents a collection of applica-
tions as one unit and lets you set the logging level on all the applications
through one call. For example, if you want to change the database and the appli-
cation logging level to debug mode, you can have an MBean make calls to the
separate applications to set the debug levels. Even the underlying technologies
to communicate with the different applications can be different; the MBean will
abstract that knowledge from the manager of the system, and the different tech-
nologies will appear as a cohesive unit.
We have reached the last step of our use case. With this step, the user has
invoked an MBean operation, and the MBean works with its resource in order to
change its logging level.
1.3.5
Notifications
In addition to the three layers presented in the architecture,
JMX
provides a
notification model that closely resembles the Java event model. Notifications
provide the final necessary component for a complete management system. The
three architectural layers allow the agent to perform configuration and control
operations on the resource, but a large portion of the management require-
ments rely on reacting to interesting events that occur to the resources. By using
notifications,
JMX
agents and MBeans can send alerts or report information to
