LongRunningServiceImpl.java

@Service
public class LongRunningServiceImpl implements LongRunningService {

  @Override
  public CallableFuture<String> someLongRunningTask() {
    final CallableFuture<String> future = 
      CallableFutureFactory.get().createFuture(String.class);
    
    // Start some asynchronous, potentially slow computation
    SomeSlowStringComputation slow = new SomeSlowStringComputation();
    slow.start(new ResultCallback<String>() {
      public void onResult(String result) {
        future.setValue(result);  
      }
    });
    
    return future;
  }
}