txtDisplay.Text = "取消!";
         }
         else
         {
             txtDisplay.Text += "完毕, 开始调用WCF!";

             //调用Service服务
             ServiceClient proxy = new ServiceClient();
             proxy.ShowMessageCompleted += OnShowMessageCompleted;
             proxy.ShowMessageAsync(1, 100, sum);       
         }
              
     }


     void OnProgressChanged(object sender, ProgressChangedEventArgs e)
     { 
         txtDisplay.Text = e.ProgressPercentage.ToString();
     }

  
     void OnDoWork(object sender, DoWorkEventArgs e)
     {       
         //throw new ApplicationException("Foo");

         while (cur_number <= 100 && !worker.CancellationPending)
         {
              Thread.Sleep(100);
              sum += cur_number;
              cur_number++;
              worker.ReportProgress(sum);
         }

         if (worker.CancellationPending)
         {
             e.Cancel = true;
         }
     }


     
     void OnShowMessageCompleted(object sender, ShowMessageCompletedEventArgs e)
     {
         if (e.Error != null)
 &n