In my previous article PI/XI: ActiveMQ - free but yet powerful JMS provider I've presented how to set up communication between SAP PI and ActiveMQ JMS server with the use of queues. As of SAP PI 7.3 we have a possibility to use not only queues but also topics. For a whole list of new SAP PI 7.3 features please have a look at this presentation: What Are the New Service Bus-Based Capabilities with SAP NetWeaver PI.
If you want to find out more about differencies between topics and queues please have a look at those short definitions - How does a Queue compare to a Topic.
Setting up ActiveMQ communication
In order to set up ActiveMQ communication you need to do two things:
Make sure you need to enable Topic support in the communication channel
The configuration for ActiveMQ topic support is a little bit different then the one presented in my previous article and requires specifing at least the clientID for the connection factory implementation as per screenshot below:
You can also specify some additional parameters if necessary (for creating durable topics for example). Now that everything is set up completely you should be able to see a new consumer on the topic on your JMS server.
One more important thing you need to remember while using topics with ActiveMQ is that you cannot browse topics as you could with queues as per Can you browse a topic.