Introduction

This article will provide more details on how to use ActiveMQ in Apache Karaf, small OSGi based runtime. Apache Karaf was previously know as ServiceMix kernel, so informations found here are applicable to Apache ServiceMix Enterprise Service Bus as well.

Installation

ActiveMQ provides Karaf features which will help you integrate and use the broker in OSGi environment. For starters you need to add the features URL to Karaf. For version 5.9.0 you can do it like this:

karaf@root> features:chooseurl activemq 5.9.0

After that you should see newly added features

karaf@root> features:list
State         Version         Name                 Repository
[uninstalled] [5.9.0         ] activemq-broker               activemq-5.9.0        
[uninstalled] [5.9.0         ] activemq-http                 activemq-5.9.0        
[uninstalled] [5.9.0         ] activemq-camel                activemq-5.9.0        
[uninstalled] [5.9.0         ] activemq-web-console          activemq-5.9.0

Installing and running the broker is as simple as installing activemq-broker feature, like

karaf@root> features:install activemq-broker

This will install and start the full broker (including the web console), just as if you started the standalone distribution.

Broker Configuration

Broker is configured using OSGi Config Admin mechanism and could be easily managed in Karaf. Configuration can be done by modifying ${KARAF_BASE}/etc/org.apache.activemq.server-default.cfg file or respective config admin property. An example of the file looks like

broker-name=amq-broker
data=${karaf.data}/${broker-name}
config=${karaf.base}/etc/activemq.xml

Mandatory properties are listed in the following table

You can also use this file to set other properties which will replace placeholders in XML configuration file, as the ${data} property is used in this example.

Default XML configuration file is located in the ${KARAF_BASE}/etc/activemq.xml by default.

Web Console

Web Console is installed by default and can be reached at http://localhost:8181/activemqweb/

The configuration for the console is done in a similar fashion to the broker itself. Configuration is located in ${KARAF_BASE}/etc/org.apache.activemq.webconsole.cfg and by default looks like

webconsole.jms.url=tcp://localhost:61616
webconsole.jmx.url=service:jmx:rmi:///jndi/rmi://localhost:1099/karaf-root
webconsole.jmx.user=karaf
webconsole.jmx.password=karaf

Optional: In order to use the ActiveMQ console with a broker configured with authentication, it is necessary to configure the username/password for JMS connection as well.

webconsole.jms.user=system
webconsole.jms.password=manager

Commands

After these simple steps you have all necessary libraries installed in the container. Also, now you have specific commands on your disposal that you can use to manage your broker:

  browse                Display selected messages in a specified destination
  bstat                 Displays useful broker statistics
  list                  Lists all available brokers in the specified JMX context
  purge                 Delete selected destination's messages that matches the message selector
  query                 Display selected broker component's attributes and statistics
  dstat                 Performs a predefined query that displays useful tabular statistics regarding the specified destination type 

activemq:[command] --help 

Broker querying

Several commands are available to query the broker. To address local brokers, you need to use the --jmxlocal parameter.

The following command displays available brokers:

karaf@root> activemq:list --jmxlocal
BrokerName = mybroker

To have more detailed informations, run:

karaf@root> activemq:query --jmxlocal

It will display informations about the connectors, list of queues, etc...

You can also browse or purge queues using the activemq:browse and activemq:purge commands.