Support for the Servlet Async API

[mdeinum]

Currently Spring WS only leverages the regular Servlet API with blocking the request handling thread. This could be improved by also allowing support for the async features of the Servlet API. Maybe parts of the async support in Spring MVC can be leveraged for this.

[snicoll]

I don't know how involved that would be but I'd rather move Spring-WS higher in the stack and make it a better citizen of Spring MVC. @rstoyanchev mentioned that this should be doable so we need to find quality time to investigate what to do.

[mdeinum]

It would probably involve copying/reusing some parts of the Async processing that is available in the DispatcherServlet.

There is a reason that the MessageDispatcherServlet is the way it is (or that it even exists). I don't recall the exact reason but I do remember that @poutsma did a presentation on this years ago (probably during the inception of Spring WS). So maybe he has some recollection and tips for this.