on page 27 of the book it says "ActiveMQ creates a broker on demand if one isn’t running already". Do I need to install and run ActiveMQ to pass the file to "incomingOrders" queue?

While I was going through the example, I started ActiveMQ (thinking that it is required) and then ran the example, I was able to see the following message: "We just downloaded: message1.xml" . Then I stopped the ActiveMQ and ran the same example again, I was still able to see the message "We just downloaded: message1.xml"

I am now confused. Does CAMEL has a builtin to ActiveMQ broker? How can I go to the "incomingOrders" queue and see that the file/message has indeed being moved to the queue?

When the VM transport is used to connect to ActiveMQ, the first to connect will start up an embedded ActiveMQ broker. All following connections within the same JVM will connect to this embedded broker. If you booted ActiveMQ up in a separate process and ran the example, it is likely that a 2nd ActiveMQ broker was created in the VM (so you didn't actually connect to the one you started manually).

If you want to connect to the broker to see queue stats, I would recommend starting up ActiveMQ manually like you did initially and connect to it using the TCP transport like so

<bean id="jms" class="org.apache.camel.component.jms.JmsComponent">
<property name="connectionFactory">
<bean class="org.apache.activemq.ActiveMQConnectionFactory">
<property name="brokerURL" value="tcp://localhost:61616" />
</bean>
</property>
</bean>

Then you can look at the JMS queue contents using jconsole or the ActiveQM web console http://activemq.apache.org/web-console.html

Cheers,
Jon

Thank you for the explanation.
I am still not 100% clear. I'll apprecaite, if you could explain the following:

1. Where does the embedded broker come from? I am simply tyring examples in the book. Examples use MAVEN so I don't know what is downloaded by MAVEN when an example is run. I ran an example on page 38:

"Go to the chapter2/spring directory in the book’s source code and run this Maven command: mvn clean compile camel:run"

The example ran successfully. My confusion is how is

1. How is ACTIVEMQ broker downloaded. Is the ACTIVEMQ downloaded and configured by MAVEN
2. I don't have SPRING installed on my machine. How are all the SPRING classes downloaded. Will every project download the SPRING files?
3. I don't understand what is going on when MAVEN is run. Please explain what magic down by MAVEN.

Thank you

Yes Maven downloads the needed JARs automatic.

You can run a maven command that lists all the dependencies it uses
mvn dependency:list

And there is a tree variant
mvn dependency:tree