GWT Asnyccall can not be executed

Question

I have written a few Asynccall to run something in Server. They work fine. But some tasks need a long time to run. I want to know their status during the execution. Then I write the new Asynccall that sends query periodically to server to check the task's status. But for the Callback, I can get only the Failure Message. I have checked the log, this AsyncCallbak can not be executed. Can anyone give me some suggestion?

        private BackendRemoteServiceAsync service = GWT.create(BackendRemoteService.class);

        Timer timer = new Timer() {
    public void run() {
        try {
           ApplicationController controller = ApplicationController
                         .getInstance();
           BackendRequest request = new BackendRequest(
                Command.COMMAND_TASK_CHECKSTATUS,
                 controller.getSessionToken());
           request.setDomain(Domains.TASK);

          ...
                  service.callBackend(request, new AsyncCallback<BackendRequest>() {

            public void onFailure(Throwable caught) {
                task.setStatus("check status failure");
            }

            public void onSuccess(BackendRequest result) {

                if (result.isValid()) {
                task.setStatus("check status Success");                                                             ...
                } else
                            ;
                }

            });
            } catch (IllegalArgumentException ex) {
                Window.alert("IllegalArgumentException: "+ ex.getMessage());
            } catch (Throwable t) {
                Window.alert(t.getMessage());
            } finally {

            }
        }
    };
    timer.scheduleRepeating(5000);

Answer 1

I have found the bug. In my method I must send some objects to backend. These objects must implement Serializeable.