Resource management and JMX - JMX in Action - page 11

objects as opposed to just data elements. A management system can send notifi-
cations that encapsulate both data and behavior; this is a powerful concept that's
familiar to object-oriented programmers but that has not been present in previ-
ous monitoring systems.
With JMX , you can emit data elements (alerts and system events) and also
send along a mechanism for interpreting the data. For example, you might send
out a notification with the status of the processor load. This information by itself
might not be useful to a management system (so what if the CPU load is 50%?);
but it would be useful to send an object that contained the data, along with a
mechanism that could provide the application's view of the load's importance.
For example, the notification could contain a method isLoadCritical() that
would return the application's concept of load criticality. The management sys-
tem could make decisions based not only on the load, but also on whether the
application was in a stressful state.

Rapid monitoring solutions
You may have experienced a development environment in which many develop-
ment teams had to coordinate efforts to provide application monitoring and
management API s. With JMX , each development team is only responsible for
developing managed beans (MBeans) for their application.
As applications are executed, they can deploy their MBeans into a waiting
JMX agent. With all the MBeans in a central but distributed host, a single man-
agement tool can manage and configure all the applications. Using JMX to pro-
vide your management solution provides the benefits of other management
technologies with less implementation difficulty and richer capabilities, due to
the object-oriented behavior and portability afforded with Java.

1.2.2 Essential JMX terms

The following terms are the building blocks for the entire JMX discussion in this
topic. We define them here, but you will learn more about them in the next sec-
tion. In addition, as other chapters cover these terms, you will acquire a more
robust understanding of them. We're presenting the terms now in order to help
explain the JMX architecture in the next section.

Manageable resource
A manageable resource is any application, device, or existing entity that can be
accessed or wrapped by Java. It is the entity that will be exposed for manage-
ment by using JMX . Applications can expose components, API s, or additional