REST server callbacks

As the asynchronous operations in some cases can take a long time and often don't end inside a single method invocation of a resource, the JAX-RS specifications provide utilities to register callbacks to invoke on suspended asynchronous response state changes. We can register two types of callbacks in RESTEasy:

• Completion callbacks executed at the end of the requests or when they fail
• Connection callbacks executed when a client connection is closed or lost

Here a sample of registration of a completion callback:

@GET
@Path("/withCallback")
publicvoid asyncGetWithCallback(@Suspendedfinal AsyncResponse asyncResponse) {
asyncResponse.register(newCompletionCallback() {
@Override
publicvoidonComplete(Throwable throwable) {
if (throwable == null) {
numberOfSuccessResponses++;
   } else {
numberOfFailures++;
lastException = throwable;
   }
   }
   });
   new Thread(new Runnable() {
@Override
publicvoid run() {
   String result = ...
asyncResponse.resume(result);
   }
   }).start...