At work I started digging into ActiveMQ, mostly because I wanted to whale on some folks who I thought had an unhealthy devotion to some mediocre, unscalable middleware. Then I stumbled upon the ActiveMQ Apollo project:
ActiveMQ Apollo is a faster, more reliable, easier to maintain messaging broker built from the foundations of the original ActiveMQ. It accomplishes this using a radically different threading and message dispatching architecture. Like ActiveMQ, Apollo is a multi-protocol broker and supports STOMP, Openwire, MQTT, SSL, and WebSockets.
If Apollo’s benchmarks prove out in actual deployment, holy smokes!! With 1.x release implying a certain amount of stability to boot. I would like to know how it scales with a high number of concurrent subscribers thou.
And ActiveMQ isn’t all that mediocre although it has some clear scaling limitations.