private SalesforceAppExPartnerAPI.SforceService Binding {
   get {
  
     try {      

      // binding
      SalesforceAppExPartnerAPI.SforceService binding = new SalesforceAppExPartnerAPI.SforceService();
      // by setting these values, we are essentially logged in to the API as this user
      binding.SessionHeaderValue = new SalesforceAppExPartnerAPI.SessionHeader();
      binding.SessionHeaderValue.sessionId = _authHeader.EXTSessionID;
      binding.Url = _authHeader.EXTServerLocation;
                           

      return binding;
     } catch (System.Web.Services.Protocols.SoapException exsoap) {
      if (exsoap.Code.ToString().Contains("API_DISABLED_FOR_ORG")) {
       throw new EXTAPIAuthFail("This edition of salesforce.com does not provide API access."
        + "API access is a standard feature of Enterprise "
        + "and Unlimited Editions.<br>"
        + "Certify your application to gain API access to "
        + "Professional Edition as well.<br><br>", exsoap);
      } else {
       throw new EXTAPIAuthFail("SoapException: Unable to validate incoming web call.", exsoap);
      }
     } catch (System.UriFormatException uriEx) {
      throw new EXTAPIAuthFail("The Server URL is invalid. " + uriEx.Message, uriEx);
     } catch (Exception e) {
      throw new EXTAPIAuthFail("Unable to connect to the API. " + e.Message, e);
     }
    } else {
     return _binding;
    }
   }
  }