Customizing order processing activity flows [Legacy]

using Mediachase.Commerce.Engine;
using Mediachase.Commerce.Orders;
using Mediachase.Commerce.WorkflowCompatibility;
using System;

namespace CustomActivity
  {
    public partial class SendNotification : Activity
      {
        /// <summary>
        /// Gets or sets the order group.
        /// </summary>
        /// <returns>The order group.</returns>
        [ActivityFlowContextProperty]
        public OrderGroup OrderGroup { get; set; }

        /// <summary>
        /// Called by the workflow runtime to execute an activity.
        /// </summary>
        /// <param name="executionContext">The <see cref="T:Mediachase.Commerce.WorkflowCompatibility.ActivityExecutionContext"/> to associate with this <see cref="T:Mediachase.Commerce.WorkflowCompatibility.Activity"/> and execution.</param>
        /// <returns>
        /// The of the run task, which determines whether the activity remains in the executing state, or transitions to the closed state.
        /// </returns>
        protected override ActivityExecutionStatus Execute(ActivityExecutionContext executionContext)
          {
            try
              {
                // Validate the properties at runtime
                this.ValidateRuntime();

                //Send notification
                this.SendEmailNotification();

                // Retun the closed status indicating that this activity is complete.
                return ActivityExecutionStatus.Closed;
              }
            catch
              {
                // An unhandled exception occured.  Throw it back to the WorkflowRuntime.
                throw;
              }
          }

        /// <summary>
        /// Calculates the sale taxes.
        /// </summary>
        private void SendEmailNotification()
          {
            //provide implementation here
          }

        /// <summary>
        /// Validates the runtime.
        /// </summary>
        private bool ValidateRuntime()
          {
            // Create a new collection for storing the validation errors
            ValidationErrorCollection validationErrors = new ValidationErrorCollection();

            // Validate the Order Properties
            this.ValidateOrderProperties(validationErrors);

            // Raise an exception if we have ValidationErrors
            if (validationErrors.HasErrors)
              {
                string validationErrorsMessage = String.Empty;

                foreach (ValidationError error in validationErrors)
                  {
                    validationErrorsMessage +=
                        string.Format("Validation Error:  Number {0} - '{1}' \n",
                        error.ErrorNumber, error.ErrorText);
                  }

                // Throw a new exception with the validation errors.
                throw new WorkflowValidationFailedException(validationErrorsMessage, validationErrors);
              }

            // If we made it this far, then the data must be valid.
            return true;
          }

        private void ValidateOrderProperties(ValidationErrorCollection validationErrors)
          {
            // Validate the To property
            if (this.OrderGroup == null)
              {
                ValidationError validationError = ValidationError.GetNotSetValidationError("OrderGroup");
                validationErrors.Add(validationError);
              }
          }
      }
  }

using Mediachase.Commerce.Engine;
using Mediachase.Commerce.Workflow.Activities;
using Mediachase.Commerce.Workflow.Activities.Cart;

namespace CustomActivity
  {
    [ActivityFlowConfiguration(Name = "CartCheckout")]
    public class CustomCartCheckout : ActivityFlow
      {
        public override ActivityFlowRunner Configure(ActivityFlowRunner runner)
          {
            return runner.If(() => ShouldProcessPayment())
                         .Do<ProcessPaymentActivity>()
                         .EndIf()
                         .Do<CalculateTotalsActivity>()
                         .Do<AdjustInventoryActivity>()
                         .Do<RecordPromotionUsageActivity>()
                         .Do<SendNotification>();
          }
      }
  }