Using the Java Discovery Protocol

I just got a question on how to get the Java Discovery protocol up and running, so I though I’d better do a quick blog on it.

First of all you need a 7u40 or later of the HotSpot JDK. Next you need to know how to start the external management agent, since the JDP server follows the life cycle of the external JMX management agent. Since it is getting late, I hereby promise to do a really long blog on how to properly set it up in a secure manner later, and simply show how to ABSOLUTELY NOT do it for now. The following example will open up an agent with absolutely no security and wide access into your JVM with both the RMI Registry and RMI Server at port 7091:

-Dcom.sun.management.jmxremote.port=7091 -Dcom.sun.management.jmxremote.rmi.port=7091 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false

 

Now, the next step is to enable JDP. This is simply done by adding the flag:

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

 

Finally, a nice structured display name can be provided to JDP by setting the name parameter like this:

-Dcom.sun.management.jdp.name=MyCluster/MyJVM

 

You should see something similar to this:

JDP

Note that there are other parameters that can be used with JDP, such as changing the multicast group, or changing the TTL for wider reach. Please see the command line documentation for further information.

 

Using JCMD

JDP can also be started when using JCMD to fire up the external management agent. Here is an example:

jcmd 5596 ManagementAgent.start jmxremote.ssl=false jmxremote.port=7091 jmxremote.rmi.port=7091 jmxremote.authenticate=false jmxremote.autodiscovery=true

 

Where 5596 is the PID of the process for which you want to start up the management agent. Again, do not start up your management agents with all the security turned off. This is just an example.

Unfortunately the name parameter is not available when starting JDP through JCMD. This is a known bug, and it will be fixed in a later version of the JVM.

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