Stateful web service support is getting some traction
It's almost magical how easy the code is, to use a stateful SOAP service in this manner.
Looks as great as Microsoft breaking 8+3 limit in filenames.
With the stateful web service support in the JAX-WS RI (although the choice of the name might have been poor), your server side code could expose multiple instances of the same service and distinguish them. This is an useful building block for any non-trivial web service interaction design, such as publish/subscribe pattern, callbacks in general, exposing a tree of objects, etc. All of this by using WS-Addressing behind the scene, so it is fully interoperable.
There are many aspects in this feature that can be done better if we are to change the JAX-WS spec, and we've long been considering to tie this to JPA. So if you are interested in seeing more improvements in this area, please let us know.