Getting Started with the Java Dynamic Management Kit 4.0

Agent Services

To simplify the development of agents for network, system, application, and service management, the Java Dynamic Management Kit supplies a set of agent services, which includes base services. Agent services are simply manageable resources, implemented as MBeans, that can perform management operations on other MBeans, thus, enabling agents to manage resources.

Filtering Service (Base Service)

The filtering service selects MBeans to be the subjects of management operations. Selection is based on the presence and values of specific attributes in object names. For example, a filter could select all the MBeans for which the attribute color is red. The filtering service is not implemented as an MBean. It is part of the infrastructure of the MBean server.

Monitoring Service

The monitoring service observes numerical values and strings, enabling the variation over time of a attribute in an MBean to be monitored. The observed attribute is monitored at intervals specified by the granularity period. An event notification is sent when the value of the attribute satisfies one of a set of conditions, thus monitors can notify other objects of several types of changes in the target. You specify the conditions when you initialize a monitor.

Timer Service

The timer service enables you to create notifications for specific dates and times, providing a scheduling mechanism based either on a one-time notification or on a repeated, periodic notification. The notifications or notification events are sent to all objects registered to receive timer events.

This service performs a function similar to that of the cron daemon of the UNIX® operating system. There are two types of timer notifications:

M-Let Service

The management applet or m-let service enables an agent to obtain MBeans from a remote Java Archive (JAR) file. The agent does this by loading an m-let text file, which specifies information on the MBeans to be obtained. The information on each MBean is specified in a single instance of a tag, called an MLET tag. The location of the m-let text file is specified by a URL. When an m-let text file is loaded, an instance of each MBean specified in the file is created.