The true-blue, Big Blue middleware package, MQSeries, is the dominant player in this market, and indeed in terms of traditional middleware it perfectly fits the bill. This means that they dump messages into queues for clients to pick up later. Messages are written to a designated file where the client can go look them up asynchronously-that is, at any time. Message-queuing middleware is used wherever data needs to be moved back and forth between disparate systems and where there is no overwhelming need for speed. The stock in trade of these packages is multiplatform data movement.
Speed is a secondary consideration.
A classic case, of course, would be stock exchanges where stock quotations must be distributed widely and very quickly. The two significant players in this market are Tibco and Talarian. In these, clients specify what data they are interested in. The publishing end of the equation broadcasts the data, and the subscribers then receive the data they were interested in. The companies use different approaches.