I've always been a big fan of asynchronous messaging and pub/sub implementations, but coming from a Java background, I'm most familiar with using JMS based messaging systems, such as JBoss MQ, HornetQ, ActiveMQ, OpenMQ, etc. I've also loosely followed the discussion of AMQP. But I recently became aware of the Data Distribution Service Specification from the Object Management Group, and found there are a couple of open-source implementations: OpenSplice OpenDDS It sounds like this stuff is focused on the kind of high-volume scenarios one tends to associate with financial trading exchanges and what-not. My current interest is more along the lines of notifications related to activity stream processing (think Twitter / Facebook) and am wondering if the DDS servers are worth looking into further. Could anyone who has practical experience with this technology, and/or a deep understanding of it, comment on how useful it is, and what scenarios it is best suited for? How does it stack up against more "traditional" JMS servers, and/or AMQP (or even STOMP or OpenWire, etc?) Edit: FWIW, I found some information at this StackOverflow thread. Not a complete answer, but anybody else finding this question might also find that thread useful, hence the added link.