Communicating with JMX agents - JMX in Action - page 193

object with its default constructor. Both classes contain the same default values
for host, port, and lookup name. The default values are the following:
■ Host— Defaults to the local host value
■ Po r t — Default value is contained in the static variable ServiceName.RMI_
CONNECTOR_PORT
■ Lookup name— Defaults to the value of ServiceName.RMI_CONNECTOR_SERVER
After creating the RmiConnectorClient object, you invoke its connect() method.
This method tells the client object to make a connection with the server-side
component of the RMI connector. After successfully connecting to the agent, you
can return the client reference—ready for use.

9.2.4 Additional uses for the RMI connector

In addition to providing RMI connectivity to a JMX agent for invoking methods
on a remote MBean server, the RMI connector offers some other useful features.
The remaining features of the RMI connector are as follows:
■ Remote notifications— The RMI connector will transmit notifications emitted
from the remote server to the remote client.
■ Connector heartbeat— Connector clients can emit a heartbeat to monitor the
connection to the connector server. Doing so allows agents and client to
retry or clean up bad connections.
■ Client context checking— This feature allows the server to verify that a client
has the correct context before invoking requested operations.

Recall that the RMI connector is contributed unsupported to the Sun JMX RI .
The RMI connector is part of Sun's commercial product, the JDMK . With that in
mind, the following sections briefly describe the three previously listed features
in more detail.

Retrieving notifications
The RMI connector provides two ways to receive notifications from a remote
MBean server. When an RMI connector client connects to an RMI connector
server, it can specify a notification receiving mode via the client's setMode()
method. The setMode() method takes a single parameter: either ClientNotifi-
cationHandler.PUSH_MODE or ClientNotificationHandler.PULL_MODE . The first
value indicates that notifications from the remote JMX agent will be pushed to
the RMI connector client, and the second value indicates that the RMI connector
client will pull notifications from the remote agent.