NotificationBroadcaster Interface

A class must implement the NotificationBroadcaster interface to be recognized as a source of notifications in the JMX architecture. This interface provides the methods for adding or removing a notification listener to or from the broadcaster. When the broadcaster sends a notification, it must send it to all listeners that are currently registered through this interface.

This interface also specifies a method that returns information about all notifications that might be sent by the broadcaster. This method returns an array of MBeanNotificationInfo objects, each of which provides a name, a description string, and the type string of the notification.

As detailed in the Javadoc API, the MBeanServerDelegate class implements the NotificationBroadcaster interface. We know from the JMX specification that it sends notifications of the following types:

• JMX.mbean.registered

• JMX.mbean.unregistered

Although broadcaster objects are almost always MBeans, they should not expose the methods of the NotificationBroadcaster interface. That is, the MBean interface of a standard MBean should never extend the NotificationBroadcaster interface. As we shall see in Chapter 12, Notification Forwarding, the remoteMBeanServer interface of connector clients provides the methods needed to register for and receive notifications remotely.