//必须设置LocalDevice之后才能运行
        public void Start()
        {
            Preconditions.Check(LocalDevice != null, "Local Device Must be set before start");
            if (isRunning)
            {
                return;            //TODO 是否需要同步锁定?有没有别的实现?
            }
            isRunning = true;

            Discoverer.StartBroadcast();
            Discoverer.StartListen();
            ChannelManager.Start();
        }