Some customers have a whole bunch of Java-based clients that communicate with HQ, usually as part of EAP 6.x. These clients use the HQ client runtime that would have been supplied with EAP 6.

The question arises: if these customers replace HQ or EAP 6 with A-MQ 7, will their existing client runtimes continue to be adequate, or will these need to be upgraded? Is the situation any different if they just upgrade their EAP 6 to EAP 7 and get Artemis that way, rather than using the A-MQ 7 product?

It is extremely common for customer who want to upgrade a large, complex system to implement the changes piece-wise. Presently it is unclear what backward compatibility Artemis/A-MQ 7 offers with earlier HQ client runtimes, so customers cannot plan such an upgrade.