The ActiveMQ component allows messages to be sent to a JMS Queue or Topic or messages to be consumed from a JMS Queue or Topic using Apache ActiveMQ. This component is based on JMS Component and uses Spring's JMS support for declarative transactions, using Spring's
JmsTemplate for sending and a
MessageListenerContainer for consuming. All the options from the JMS component also applies for this component.
To use this component make sure you have the
activemq-core.jar on your classpath along with any Camel dependencies such as
Transacted and caching
See section Transactions and Cache Levels below on JMS page if you are using transactions with JMS as it can impact performance.
destinationName is an ActiveMQ queue or topic name. By default, the
destinationName is interpreted as a queue name. For example, to connect to the queue,
You can include the optional
queue: prefix, if you prefer:
To connect to a topic, you must include the
topic: prefix. For example, to connect to the topic,
See Options on the JMS component as all these options also apply for this component.
Configuring the Connection Factory
This test case shows how to add an
ActiveMQComponent to the CamelContext using the
activeMQComponent() method while specifying the brokerURL used to connect to ActiveMQ.
Configuring the Connection Factory using Spring XML
You can configure the ActiveMQ broker URL on the
ActiveMQComponent as follows
Using Connection Pooling
When sending to an ActiveMQ broker using Camel it's recommended to use a pooled connection factory to efficiently handle pooling of JMS connections, sessions and producers. This is documented on the ActiveMQ Spring Support page.
You can grab ActiveMQ's
org.apache.activemq.pool.PooledConnectionFactory with Maven:
And then setup the
activemq Camel component as follows:
destroy methods on the pooled connection factory. This is important to ensure the connection pool is properly started and shutdown.
Important information about when using transactions
If you are using transactions then see more details at JMS. And remember to set
CACHE_CONSUMER if you are not using XA transactions. This can dramatically improve performance.
PooledConnectionFactory will then create a connection pool with up to 8 connections in use at the same time. Each connection can be shared by many sessions. There is an option named
maximumActive you can use to configure the maximum number of sessions per connection; the default value is
500. From ActiveMQ 5.7: the option has been renamed to better reflect its purpose, being named as
maximumActiveSessionPerConnection. Notice the
concurrentConsumers is set to a higher value than
maxConnections is. This is okay, as each consumer is using a session, and as a session can share the same connection, we are in the safe. In this example we can have
8 * 500 = 4000 active sessions at the same time.
Invoking MessageListener POJOs in a Camel route
The ActiveMQ component also provides a helper Type Converter from a JMS
MessageListener to a Processor. This means that the Bean component is capable of invoking any JMS
MessageListener bean directly inside any route.
So for example you can create a
MessageListener in JMS like this:
Then use it in your Camel route as follows
That is, you can reuse any of the Camel Components and easily integrate them into your JMS
Using ActiveMQ Destination Options
Available as of ActiveMQ 5.6
You can configure the Destination Options in the endpoint URI, using the
destination. prefix. For example to mark a consumer as exclusive, and set its prefetch size to
50, you can do as follows:
Consuming Advisory Messages
ActiveMQ can generate Advisory messages which are put in topics that you can consume. Such messages can help you send alerts in case you detect slow consumers or to build statistics (number of messages/produced per day, etc.) The following Spring DSL example shows you how to read messages from a topic.
The below route starts by reading the topic ActiveMQ.Advisory.Connection. To watch another topic, simply change the name according to the name provided in ActiveMQ Advisory Messages documentation. The parameter
mapJmsMessage=false allows for converting the
org.apache.activemq.command.ActiveMqMessage object from the JMS queue. Next, the body received is converted into a String for the purposes of this example and a carriage return is added. Finally, the string is added to a file
If you consume a message on a queue, you should see the following files under the
data/activemq folder :
containing the following string:
Getting Component JAR
You will need this dependency
ActiveMQ is an extension of the JMS component released with the ActiveMQ project.