This is from a presentation I gave at TheServerSide Java Symposium in March of 2005. Please don't use these materials for presentations without contacting me.
The Presentation
This presentation (in PowerPoint) covers why we'd want to take web request processing asynchronous, what problems it solves, and two methods for implementing asynchronous processing.
Moving Web Apps From Synchronous to Asynchronous Processing
The Example App
The example app is a simple application showing the use of the "execAndWait" interceptor to provide the user an intermediate "in progress" page as well as a web request which is bridged into a JMS message to be handled asynchronously in a "fire and forget" mode.