我有一个Spring MVC 3.2应用程序，我需要向此Web服务添加一个Long Polling进行实时聊天。我关注了这篇文章Spring MVC
3.2 Preview：Chat Sample
。

TopicRestController：

 private final Map<DeferredResult<String>, Long> chatRequests =
            new ConcurrentHashMap<DeferredResult<String>, Long>();

 @RequestMapping(value="/{topicId}/updates" , method=RequestMethod.POST)
public @ResponseBody DeferredResult<String> isNewTopic(
        @PathVariable Long topicId,
        Model model, HttpSession session,
        @RequestParam(required = true) String data) throws InterruptedException, CircularDefinitionException{
    logger.info("New long polling request "+topicId);
    final DeferredResult<String> result = new DeferredResult<String>();
    this.chatRequests.put(result, topicId);

    result.onCompletion(new Runnable() {
        @Override
        public void run() {
            chatRequests.remove(result);
            logger.info("Remove request from queue!");
        }
      });

        Timestamp timestamp = new Timestamp(Long.valueOf(data)*1000L);
        String updates = talkService.findNewTopicResponce(topicId,timestamp);
        if (!updates.isEmpty()) {
            result.setResult(updates);
        }

    return result;
}

@RequestMapping(value= "/{categoryId}" + "/addAnswer", method=POST) 
public @ResponseBody Map respTopic(
        @PathVariable Long categoryId,
        @RequestParam String msg,
        @RequestParam(required = false) String imageUrl,
        @RequestParam(required = false) String title,
        @RequestParam long talkId,
        HttpServletRequest request
        ) throws CircularDefinitionException, MessagingException,TalkNotExistException{
     ........................
    for (Entry<DeferredResult<String>, Long> entry :  this.chatRequests.entrySet()){
                            if(entry.getValue().equals(talkId)){        
                                entry.getKey().setResult(""+talkId);
                            }
                        }

    }

现在的问题是：

当我打电话给“ / {topicId} /
updates”时，如果30秒后没有任何答案，服务器将返回错误500，如果有人写了一条消息，服务器将返回正确的消息，但服务器始终在30秒后响应，则我需要服务器当有人写新消息时立即做出响应，而不是在超时过程中做出响应。