private async void LoadProductsAndCustomers()
        {
            AppServiceClient proxy = null;

            try
            {
                proxy    = new AppServiceClient("BasicHttpBinding_IAppService");
                Products = await proxy.GetProductsAsync();

                Customers = await proxy.GetCustomersAsync();

                proxy.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                if (proxy != null)
                {
                    proxy.Close();
                }
            }
        }