Java Reference
In-Depth Information
Figure 1.3
Up-close view of a
JMX agent showing
adapters and
connectors for HTTP,
RMI, and Jini
Our use case moves through this layer with step 1 from the previous list: a user
uses a management tool to connect with the
JMX
agent. The
JMX
agent con-
tains an MBean that can manage the bicycle shop application. However, in its
distributed layer, it contains a component that allows clients to make a connec-
tion to the agent. This component can connect the user to the agent via a web
browser, Java
RMI
, or
SNMP
. As shown in figure 1.3, the user's management tool
can be a
JMX
-knowledgeable management tool or a tool using another technol-
ogy or protocol.
Once the connection to the agent has been made, the user can use a manage-
ment tool to interact with MBeans registered in the agent. At this point, the use
case moves into the agent layer of the architecture.
1.3.3
The agent layer
The main component of the agent layer is the MBean server. An MBean server is
a Java object that acts as a registry for MBeans; it's the heart of a
JMX
agent. In
addition, the agent layer provides four agent services that make managing
MBeans easier: timer, monitoring, dynamic MBean loading, and relationship
services. Figure 1.4 shows a
JMX
agent's MBean server and agent services.
The agent layer provides access to managed resources from the management
application. A
JMX
agent can run in a JVM embedded in the machine that hosts
the resources, or it can be remotely located. The agent does not require knowledge
of the resources that it exposes or the manager application that uses the exposed
MBeans. It acts as a service for handling MBeans and allows manipulation of
MBeans through a collection of protocols exposed via connectors or adapters.
Moving to step 2, the user finds the MBean that manages the configuration
for the bicycle shop application. After finding the MBean, the user invokes an
