如何使 WCF RESTful 服务异步工作?

我正在构建 WCF 休息服务，它是客户端.我的计划是，那个客户对服务了解不多，只知道调用方法和预期结果的正确 URL.

I'm building WCF rest service and it's client. I plan, that client does not know much about the service, just right URL's to call methods and expected results.

我的服务合同是:

[WebInvoke(Method="POST", UriTemplate="/tasks")]
[OperationContract]
void SubmitTask(Transaction task);

[WebGet(UriTemplate = "/tasks/{taskId}")]
[OperationContract]
[XmlSerializerFormat]
Transaction GetTask(string taskId);

SubmitTask 是这样实现的:

SubmitTask is realized like:

SubmitTask(Transaction task)
{
   DoSomethingWithTask(task);
   task.Status = "SomeStatus";
   DoSomethingElseWithTaks(task);
   task.Status = "SomeOtherStatus";
}

我对客户的期望:

ButtonClick()
{
   SubmitTask(task);
   while(true)
   {
      string status = Transaction GetTask(task.taskId).Status;
      Textbox.Text+= status;
      if(status==ok)
         break;
      Thread.Sleep(1000); 
   }
}

问题是-服务端没有执行GetTask，而所有SubmitTask操作都完成了，所以我只在客户端得到最后一个任务状态.这种情况下如何实现异步操作?

The problem is - GetTask is not performed on service side, while all SubmitTask operations are completed, so I get only last task status on client side. How to realize asynchronos operation performing in this situation?

提前致谢！