Resource management and JMX - JMX in Action - page 12

resources for a JMX environment to manage. Manageable resources can even be
network devices such as printers. The manageable resource is the entity man-
aged by a JMX MBean.
MBean
An MBean (managed bean) is a Java class that meets certain naming and inherit-
ance standards dictated by the JMX specification. Instantiated MBeans are Java
objects that expose management interfaces for the manipulation and access of
manageable resources. An MBean's management interface is made up of the
MBean's attributes and operations that are exposed for management.
Management applications access MBeans to access attributes and invoke
operations. This topic covers three types of MBeans: Standard, Dynamic, and
Model MBeans. Each type of MBean has specific advantages for specific
resources. MBeans reside in another JMX component called the MBean server.
MBean server
An MBean server is a Java class that manages a group of MBeans. It is the heart
of the JMX management environment—it acts as a registry for looking up
MBeans. The MBean server exposes the management interface of any registered
MBean, but it never exposes the object reference. In addition, the MBean server
is implemented to present users with an identical interface regardless of the type
of MBean being accessed: it treats all MBeans equally. The MBean server also
provides methods for performing queries to find MBeans and for other objects
to register as notification listeners (like event listeners) with MBeans.
JMX agent
A JMX agent is a Java process that provides a set of services for managing a set of
MBeans—it is the container for an MBean server. JMX agents provide services
for creating MBean relationships, dynamically loading classes, simple monitor-
ing services, and timers.
Agents can expect to have a set of protocol adapters and connectors that
enable remote and different clients to make use of the agent. Protocol adapters
and connectors are Java classes, usually MBeans, which can internally map an
outside protocol (like HTTP or SNMP ) or expose the agent to remote connectivity
(like RMI or Jini). This means JMX agents can be used by a variety of different
management protocols and tools.