Java Message Service (JMS) is a Java library that allows you to do Message Oriented Middleware (MOM) in order to facilitate messaging between different parts of a distributed system. This type of messaging can be useful in large enterprise information systems that require systems to communicate in a simple manner.
The JMS provides two models for messaging: a point-to-point queuing model and a publish/subscribe model. In the point-to-point model, the message producer knows where it wants to send the message, and it sends it to the queue which is then taken by the receiver. The publish/subscribe model allows for multiple receivers to subscribe to receive certain messages selected by topic. RSS feeds seem to follow a similar pattern as that of the publish/subscribe model in that new content is published and multiple subscribers to that feed can retrieve the new content.
I’m not an expert by any means in using JMS. I just think that the MOM architecture is just an interesting concept. For more information on JMS, see Wikipedia.