An MBean should have “just the right amount” of instrumentation. But what does that mean, exactly? Well, it depends on who will be looking at the information provided by the management interface of your MBean. Will it be a developer, or an operator at a management console? The answer is important. Because management is focused on the health of a resource, an MBean should contain the minimum amount of information necessary to ensure that the resource is functioning within normal parameters. It is up to you to define these parameters. Remember, there is overhead associated with management, so use it carefully.
At a fundamental level, management consists of three aspects:
The current state of what’s going on in the system. It consists of an MBean’s attributes.
How to impose control on the system. It consists of an MBean’s operations.
Notification of something potentially harmful happening in the system. It is an MBean notification.
Let’s put this in a context to which most of us can relate: an automobile. An automobile is a system that can be monitored and controlled, and can send events to its operator. Here are some examples of each of these aspects of management:
To monitor what is happening in cars, manufacturers provide gauges that measure speed, fuel, the rate of rotation of revolving shafts, oil pressure, battery power, and engine temperature. These enable drivers to monitor the current state of their cars to better manage ...