C#判断WebService接口是否可用

      using MSXML2;   

          public bool InterfaceEnble()
         {
             string url = "http://localhost:81/WebServiceLogin.asmx";
             XMLHTTP http = new XMLHTTP();
             try
             {
                 http.open("GET ", url, false, null, null);
                 http.send(null);
                 int iStatus = http.status;
                 //如果状态不为200，就是不能调用此接口
                 if (iStatus == )
                     return true;
             }
             catch (Exception ex)
             {
                 MessageBox.Show("接口调用失败," + ex);
             }

             return false;
         }

判断接口是否可用