@RequestMapping(value="/asyncStart", method=RequestMethod.GET)
    @ResponseBody
    public String asyncStart(HttpSession session) {
        Future<Report> report = commonService.longTask();
        session.setAttribute("report", report);
          return "startAsync";
    }

@Async
    public Future<Report> longTask() {
        int count = 0;
        Report report = new Report();
        report.setDescription("Task start!");
        try {
              while(count!=100){
                  count++;
                  Thread.sleep(1000);
                  report.setDescription("Task complete "+count);
              }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return new AsyncResult(report);
    }

public class Report {
    private String description;
    ...
    set/get

@RequestMapping(value = "/asyncResult", method=RequestMethod.GET)
    @ResponseBody
    public String reportStatus(HttpSession session) {
        Future<Report> report = (Future<Report>)session.getAttribute("report");
        try {
        Report result = report.get();
            if(report.isDone()) {
                return "COMPLETE";
            } else {
                return "STILL WORKING: " + result.getDescription();
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
            return "---";
    }

while(count!=100){
                  count++;

session.setAttribute("count", count);