a very simple example of developing activemq plugins.

com.mallow.activemq.FoxBrokerPlugin

just for show, log something when messages sended or produced.

com.mallow.activemq.LimitQueueSizePlugin

A plugin can be useful in test enviroment, which will discard all messages when there are more than 1000 messages pending.

1. put the FoxActivemqPlugin jar into activemq's lib folder.
2. add this config to activemq.xml:

<plugins>
    <bean xmlns="http://www.springframework.org/schema/beans" id="testPlugin"  class="com.mallow.activemq.FoxBrokerPlugin"/>
    <bean xmlns="http://www.springframework.org/schema/beans" id="purgePlugin" class="com.mallow.activemq.LimitQueueSizePlugin"/>
</plugins>

for more detail, see http://activemq.apache.org/developing-plugins.html