ActiveMQ: Bridging Topics to Queues

Most recently, I had the need to create a bridge from Topics to Queues to create stateless services that can pick up messages in parallel. Essentially, I wanted to configure the following (in the message broker):

Topic to Queue Bridge

While there are many other ways to do this, I wanted to experiment with ActiveMQ support for this. The following is how I configured it locally (in my dev box):

Use a Docker Image
I used an ActiveMQ docker image found here. It was pretty straightforward and was able to get it running after a few commands. Here is what I did to define a baseline (this is from the instructions in the link above):

  docker run --user root --rm -ti \
  -v /Users/alberto/workspace/docker/activemq/conf:/mnt/conf \
  -v /Users/alberto/workspace/docker/activemq/data:/mnt/data \
  rmohr/activemq:5.15.4-alpine /bin/sh

Notice the following:

• I created the /conf and /data directory in my dev box.
• I mounted these folders into the /mnt/* respective to my local box.
• As the end of this command, a shell will be started inside the docker container

Then, I had to do the following (within the docker container):

  chown activemq:activemq /mnt/conf
chown activemq:activemq /mnt/data
cp -a /opt/activemq/conf/* /mnt/conf/
cp -a /opt/activemq/data/* /mnt/data/
exit

Now, I have the configuration in my "conf" folder.

Configure ActiveMQ
Within the "conf" folder, we need to edit the activemq.xml file.

	<!--
	Licensed to the Apache Software Foundation (ASF) under one or more
	contributor license agreements. See the NOTICE file distributed with
	this work for additional information regarding copyright ownership.
	The ASF licenses this file to You under the Apache License, Version 2.0
	(the "License"); you may not use this file except in compliance with
	the License. You may obtain a copy of the License at
	http://www.apache.org/licenses/LICENSE-2.0
	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->
	<!-- START SNIPPET: example -->
	<beans
	xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
	http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">
	<!-- Allows us to use system properties as variables in this configuration file -->
	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
	<property name="locations">
	<value>file:${activemq.conf}/credentials.properties</value>
	</property>
	</bean>
	<!-- Allows accessing the server log -->
	<bean id="logQuery" class="io.fabric8.insight.log.log4j.Log4jLogQuery"
	lazy-init="false" scope="singleton"
	init-method="start" destroy-method="stop">
	</bean>
	<!--
	The <broker> element is used to configure the ActiveMQ broker.
	-->
	<broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost" dataDirectory="${activemq.data}">
	<destinationPolicy>
	<policyMap>
	<policyEntries>
	<policyEntry topic=">" >
	<!-- The constantPendingMessageLimitStrategy is used to prevent
	slow topic consumers to block producers and affect other consumers
	by limiting the number of messages that are retained
	For more information, see:
	http://activemq.apache.org/slow-consumer-handling.html
	-->
	<pendingMessageLimitStrategy>
	<constantPendingMessageLimitStrategy limit="1000"/>
	</pendingMessageLimitStrategy>
	</policyEntry>
	</policyEntries>
	</policyMap>
	</destinationPolicy>
	<!--
	The managementContext is used to configure how ActiveMQ is exposed in
	JMX. By default, ActiveMQ uses the MBean server that is started by
	the JVM. For more information, see:
	http://activemq.apache.org/jmx.html
	-->
	<managementContext>
	<managementContext createConnector="false"/>
	</managementContext>
	<!--
	Configure message persistence for the broker. The default persistence
	mechanism is the KahaDB store (identified by the kahaDB tag).
	For more information, see:
	http://activemq.apache.org/persistence.html
	-->
	<persistenceAdapter>
	<kahaDB directory="${activemq.data}/kahadb"/>
	</persistenceAdapter>
	<!--
	The systemUsage controls the maximum amount of space the broker will
	use before disabling caching and/or slowing down producers. For more information, see:
	http://activemq.apache.org/producer-flow-control.html
	-->
	<systemUsage>
	<systemUsage>
	<memoryUsage>
	<memoryUsage percentOfJvmHeap="70" />
	</memoryUsage>
	<storeUsage>
	<storeUsage limit="100 gb"/>
	</storeUsage>
	<tempUsage>
	<tempUsage limit="50 gb"/>
	</tempUsage>
	</systemUsage>
	</systemUsage>
	<!--
	The transport connectors expose ActiveMQ over a given protocol to
	clients and other brokers. For more information, see:
	http://activemq.apache.org/configuring-transports.html
	-->
	<transportConnectors>
	<!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
	<transportConnector name="openwire" uri="tcp://0.0.0.0:61616?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
	<transportConnector name="amqp" uri="amqp://0.0.0.0:5672?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
	<transportConnector name="stomp" uri="stomp://0.0.0.0:61613?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
	<transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
	<transportConnector name="ws" uri="ws://0.0.0.0:61614?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
	</transportConnectors>
	<!-- destroy the spring context on shutdown to stop jetty -->
	<shutdownHooks>
	<bean xmlns="http://www.springframework.org/schema/beans" class="org.apache.activemq.hooks.SpringContextHook" />
	</shutdownHooks>
	<!-- custom virtual destinations -->
	<destinationInterceptors>
	<virtualDestinationInterceptor>
	<virtualDestinations>
	<compositeTopic name="t.example.service.event">
	<forwardTo>
	<queue physicalName="q.example.service.review" />
	</forwardTo>
	</compositeTopic>
	</virtualDestinations>
	</virtualDestinationInterceptor>
	</destinationInterceptors>
	</broker>
	<!--
	Enable web consoles, REST and Ajax APIs and demos
	The web consoles requires by default login, you can disable this in the jetty.xml file
	Take a look at ${ACTIVEMQ_HOME}/conf/jetty.xml for more details
	-->
	<import resource="jetty.xml"/>
	</beans>
	<!-- END SNIPPET: example -->

view raw activemq.xml hosted with ❤ by GitHub

The important lines here are from 125 to 136 where I use "VirtualDestinations".

Test Message Forward
You can now go to the admin console at:

  http://localhost:8161/admin/send.jsp

and send a message to the topic. You will see messages forwarded to the queues of your choice.