JMS stands for Java Message Service which is an API which is used by
middleware service providers such as ActiveMQ, JBoss MQ, Rabbit MQ,
etc. Its main purpose is to allow disparate systems to communicate based
on a common platform. Which means that if I have my front end written
in .Net and my back end written in Java for example, one way of
communicating between the two (other than Webservices etc) is to use a
JMS provider in a publisher-subscriber or peer-to-peer configuration.
In our own project we have used JMS not to communicate between two disparate systems but to get the asynchronous capability integrated to our application. What we do is push the message into a queue and get along with the rest of the business process. But it seems this is not the correct way of achieving this. Of course at the end of the day we have achieved asynchronous behavior, but not in the right way. A solution just came to light when Spring 3 was released. Spring 3 provided an implementation allowing asynchronous capability with the @Async annotation. I will not go into the details of this feature as it is very well explained here.