可扩展类库强制取消异步调用

http://developer.nokia.com/community/wiki/Portable_Class_Library_with_async_/_await_support_for_Windows_Phone

  TaskServiceAgent.TaskServiceSoap agent = new TaskServiceAgent.TaskServiceSoapClient();//远程webservcie
                 var q=new TaskFactory().FromAsync<int, TaskServiceAgent.Task[]>(agent.BeginGetTaskList, agent.EndGetTaskList,92,null);
                 var m = q.Result;

FromAsync<int, TaskServiceAgent.Task[]>(参数，结果类型>