using System;

using CMS.GlobalHelper;

using CMS.SettingsProvider;

using CMS.Ecommerce;

  /// <summary>

  /// CustomGatewayLoader e-commerce loader class. Partial class ensures correct registration.

  /// </summary>

  ///

[CustomGatewayLoader]

public partial class CMSModuleLoader

{

   #region "Macro methods loader attribute"

  /// <summary>

  /// Module registration

  /// </summary>

  private class CustomGatewayLoaderAttribute : CMSLoaderAttribute

   {

      /// <summary>

      /// Constructor

      /// </summary>

      public CustomGatewayLoaderAttribute()

       {

          // Require E-commerce module to load properly.

           RequiredModules = new string[] { ModuleEntry.ECOMMERCE };

       }

      /// <summary>

      /// Initializes the module.

      /// </summary>

      public override void Init()

       {

          // This line provides the ability to register the classes via web.config cms.extensibility section from App_Code.

           ClassHelper.OnGetCustomClass += GetCustomClass;

       }

      /// <summary>

      /// Gets the custom class object based on the given class name. This handler is called when the assembly name is App_Code.

      /// </summary>

      private static void GetCustomClass(object sender, ClassEventArgs e)

       {

          if (e.Object == null)

           {

              // Provide your custom classes.

              switch (e.ClassName.ToLower())

               {

                  // Create a custom getaway object inheriting from CMSPaymentGatewayProvider.

                  case "customgateway":

                       e.Object = new CustomGateway();

                      break;

               }

           }

       }

   }

   #endregion

}

using System;

using System.Collections.Generic;

using System.Text;

using System.Web;

using System.Collections;

using CMS.EcommerceProvider;

using CMS.GlobalHelper;

using CMS.UIControls;

using CMS.ExtendedControls;

  /// <summary>

  /// Class representing the Custom Gateway processor.

  /// </summary>

public class CustomGateway : CMSPaymentGatewayProvider

{

  /// <summary>

  /// Returns a payment gateway form with custom controls.

  /// </summary>

  /// <returns></returns>

  public override CMSPaymentGatewayForm GetPaymentDataForm()

   {

      try

       {

          return (CMSPaymentGatewayForm)this.ShoppingCartControl.LoadControl("~/CustomGatewayForm.ascx");

       }

      catch

       {

          return null;

       }

   }

  /// <summary>

  /// Process payment.

  /// </summary>

  public override void ProcessPayment()

   {

      // Get payment gateway url.

      string url = this.GetPaymentGatewayUrl();

      if (url != "")

       {

          // Initialize payment parameters.

          Hashtable parameters = InitializePaymentParameters();

          // Add required payment data to the url.

           url = GetFullPaymentGatewayUrl(url, parameters);

          // Redirect to payment gateway to finish payment.

          this.ShoppingCartControl.Page.Response.Redirect(url);

       }

      else

       {

          // Show error message - payment gateway url not found.

          this.ErrorMessage = "Unable to finish payment: Payment gateway url not found.";

          // Update payment result.

          this.PaymentResult.PaymentDescription = this.ErrorMessage;

          this.PaymentResult.PaymentIsCompleted = false;

          // Update order payment result in the database.

          this.UpdateOrderPaymentResult();

       }

   }

  /// <summary>

  /// Returns table with initialized payment parameters.

  /// </summary>

  /// <returns></returns>

  private Hashtable InitializePaymentParameters()

   {

      Hashtable parameters = new Hashtable();

       parameters["orderid"] = this.ShoppingCartInfoObj.OrderId;

       parameters["price"] = this.ShoppingCartInfoObj.TotalPrice;

       parameters["currency"] = this.ShoppingCartInfoObj.Currency.CurrencyCode;

       parameters["cardnumber"] = Convert.ToString(this.ShoppingCartInfoObj.PaymentGatewayCustomData["CustomGatewayCardNumber"]);

      return parameters;

   }

  /// <summary>

  /// Returns payment gateway url with payment data in query string.

  /// </summary>

  /// <param name="url">Payment gateway url.</param>

  /// <param name="parameters">Initialized payment paremeters.</param>

  /// <returns></returns>

  private string GetFullPaymentGatewayUrl(string url, Hashtable parameters)

   {

      foreach (DictionaryEntry parameter in parameters)

       {

          // Add payment data to the url.

           url = URLHelper.AddParameterToUrl(url, Convert.ToString(parameter.Key), HttpUtility.UrlEncode(Convert.ToString(parameter.Value)));

       }

      return url;

   }

}

If you registered your custom payment gateway as a global payment method, you need to enable it for use on the current site.

You can do this in CMS Desk -> E-commerce -> Configuration -> Store settings -> Global objects.