The Tomcat thing is documented here: http://tomcat.apache.org/tomcat-6.0-doc/aio.html
The DWR thing is documented here: http://getahead.org/dwr/development/pollactions
I've just done some refactoring to create a ContainerAbstraction interface that you will need to implement. I will attach the interface because I don't want to check this in until I've double checked with Jose on some minor effects it has on the Spring stuff.
This is not functioning correctly.
I think we should be looking at implementing Servlet 3.0 async processing instead of trying to implement container specific APIs.
Please see DWR-590.