Fun and profit in your first few hours with JBoss A-MQ

As part of my pitch to the Virtual JBoss User Group, I’ve been trying to think of the best way to explain how to get started with Red Hat JBoss A-MQ(A-MQ) and how to compare / contrast it with Apache ActiveMQ. While they share the same lineage, the user experience is very different.

So I thought I’d give you a few notes on how to play around with it and to visually work with the administrative interface. To follow along, you’ll need to download both Apache ActiveMQ and JBoss A-MQ because I’m going to rely on the example code bundled with ActiveMQ.

Discovering the A-MQ web interface

After starting A-MQ from the command line, navigate to the hawtio-based interface by loading http://localhost:8181, which is different from ActiveMQ’s default port. Login with username admin, password admin, which are the defaults, and you’ll see something like this:

activemq-landing-page

Watching messages in the queue

Let’s start by sending and receiving some messages. By default, A-MQ runs only the OpenWire protocol. Since ActiveMQ ships example code with multiple protocols, let’s focus by opening ActiveMQ’s example code for OpenWire from this directory:

This code produces and consumes TextMessage messages through two classes: Producer and Listener. After Producer sends 10,000 messages, it sends a message with a body of “SHUTDOWN” which causes Consumer to shutdown and stop listening. To run this with A-MQ, you’ll need to change the hard coded user and password  to “admin” / “admin.”

To make the admin console come to life, we need to slow down the Listener and Producer before we run them because otherwise everything will happen so fast that you won’t be able to observe what’s happening on the hawtio interface. There are many ways to do this, but I just added some sleep statements in the code (about line 48 in Listener class):

Now let’s watch the messages. Start the Producer class and then the Consumer class (they each run independently). The hawtio interface should update pretty fast, and you’ll see this by default (I renamed my queue in the code to “test2,” which is why your queue name will probably say “example”):

a-mq active

Interesting information, but I really just want to know more about the messages actually flowing through the queue at this point. If you click on the “Edit Chart” button near the top, you can the information. I just picked “Queue Size” because I just want to know how many messages get queued up:

queue-size

Now let’s run it again, but this time start the Producer first and then wait 20-30 seconds before starting the Consumer. You should see something like this:

queue-size-chart

Your Queue size should grow, stabilize for a while, and then start to shrink. Kind of cool. You might actually see a visual graph too — I think mine didn’t show up in the screenshot because I compressed the view.

Let’s send a message from A-MQ’s hawtio interface to your Java code

For me, I started a git repo on the ApacheMQ examples — you may want to do the same before you start the following example. Since we’re going to send a TextMessage from the hawtio web interface to our Java code, let’s add a little code to the while loop in the Listener class as follows:

As you can see, we’re going to listen for a TextMessage that says “HELLO.” Set a break point on the System.out if you want or just run the Listener class. The Listener is waiting for a message that says “HELLO”. Don’t start the Producer class this time.

Instead, return to the hawtio interface. Click on your queue, which is probably named “example” but could be whatever you named your queue from above (I named mine test2). Then click on “operations” in the context menu as follows:

activemq-operations

Now, scroll down a bit and create a TextMessage by clicking on the ambiguously named option “Send text message(java.lang.string, java.lang.string, java.lang.string)” and enter the following:

amq-hello-msg

If everything work correctly (and it always does on my machine, btw), then you should see something like the following:

hello-world

Good luck out there, and let me know how your mileage varies…

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