WCF 回调中操作线程

回调的类    
[CallbackBehavior(ConcurrencyMode = ConcurrencyMode.Reentrant, UseSynchronizationContext = false)]
    public class backcall : LiuLanCallback
    {

        static string ss;
        //所有控件的父类，用于控制控件
        private static Control ctrl = null;
        delegate void wei();//委托
        public backcall(){}
        //初始化,在ui线程里，将控件传过来
        public backcall(Control rb)
        {
            ctrl = rb;
        }
        //设置对ui的更改
        public void message1()
        {
            ctrl.Text = "";
            Thread.Sleep();
        }
        //回调的的方法，调用 委托
        public void ToGetMessage()
        {
            if (ctrl.InvokeRequired)
            {
                wei w = new wei(message1);
                ctrl.BeginInvoke(w);   //异步调用 同步用invoke
            }
        }
    }