JMS is ascynchronous in nature... meaning the sender is decoupled from the reciever. You could create a situation where the sender sends a message and then blocks on a response from the reciever... but this would be a misuse of the technology and much easier to do as a straight scynchronous method-call. So JMS is ascynchronous but can be used to mimic a scynchronous call if necessary.
Paper jam tastes about as you would expect. Try some on this tiny ad: