Chapter 40. Developing Asynchronous Applications

Polling approach — To invoke the remote operation using the polling approach, you call a method that has no output parameters, but returns a javax.xml.ws.Response object. The Response object (which inherits from the javax.util.concurrency.Future interface) can be polled to check whether or not a response message has arrived.

Callback approach — To invoke the remote operation using the callback approach, you call a method that takes a reference to a callback object (of javax.xml.ws.AsyncHandler type) as one of its parameters. When the response message arrives at the client, the runtime calls back on the AsyncHandler object, and gives it the contents of the response message.