Hawkular currently uses ActiveMQ as a JMS provider. ActiveMQ implements JMS 1.1 but not JMS 2.0. JMS 2.0 has been out for some time and is already in WildFly 9. JMS 2.0 has some nice changes including async sending of messages. In JMS 1.1 the client blocks until the server acknowledges successful delivery of the message. In 2.0 the sender can receive that acknowledgement asynchronously via a callback. This can have serious implications for scalability.

HornetQ is the default JMS provider in WildFly 8/9. If I am not mistaken part of the reason we elected to go with ActiveMQ was due to the uncertainty around the future of HornetQ. HornetQ is now ActiveMQ Artemis and is the JMS provider in WlidFly 10 which is the basis for EAP 7. It does not look like ActiveMQ will implement JMS 2.0 any time soon which again, has been out for some time. Considering all this, we should switch to the default JMS provider in WildFly so that we can start using JMS 2.0 and/or using Artemis directly when it makes sense.