Seam makes it very easy to perform work asynchronously from a web request. When most people think of asynchronicity in Java EE, they think of using JMS. This is certainly one way to approach the problem in Seam, and is the right way when you have strict and well-defined quality of service requirements. Seam makes it easy to send and recieve JMS messages using Seam components.

But for many usecases, JMS is overkill. Seam layers a simple asynchronous method and event facility over the EJB 3.0 timer service.