
		Previous	Contents		Next

Chapter 6

Java Discovery Protocol (JDP)

The Java Discovery Protocol (JDP) is a protocol that enables technologies, in particular, Java Mission Control and Java Flight Recorder, to discover manageable JVMs across the same network subnet.

A manageable JVM is one that has the Java Management Extensions (JMX) agent running. JDP is multicast-based and works like a beacon; it broadcasts the JMX service URL (see the class JMXServiceURL) required to connect to the external JMX agent. This enables technologies to detect JVMs that have failed or are no longer available for monitoring.

Enabling and Configuring JDP

To enable JDP, specify the following option at the command line when starting a Java application:

-Dcom.sun.management.jmxremote.autodiscovery=true

Note - Enabling JDP does not affect JMX security. To enable and configure JMX security, see Chapter 2, Monitoring and Management Using JMX Technology.

The following table describes other properties that you may set to configure JDP:

Property	Description	Default Value
`-Dcom.sun.management.jmxremote.autodiscovery`	Enables autodiscovery (JDP) on the network subnet	false
`-Dcom.sun.management.jdp.pause`	Specifies the broadcast interval in seconds	5
`-Dcom.sun.management.jdp.ttl`	Time-to-live in seconds for autodiscovery packets	1
`-Dcom.sun.management.jdp.address`	Multicast address to send autodiscovery packets	224.0.23.178
`-Dcom.sun.management.jdp.port`	Multicast port to send autodiscovery packets. Enables autodiscovery even if the `com.sun.management.jmxremote.autodiscovery` property has not been set.	7095
`-Dcom.sun.management.jdp.name`	Broadcast name of the JVM	No default
`-Dcom.sun.management.jdp.source_addr`	Address of source interface to use for broadcast	Automatically assigned