Add clarifying comments

Signed-off-by: Marc Duiker <[email protected]>

Author: marcduiker

tutorials/workflow/csharp/combined-patterns/WorkflowApp/OrderWorkflow.cs

@@ -7,6 +7,7 @@ internal sealed class OrderWorkflow : Workflow<Order, OrderStatus>
 {
    public override async Task<OrderStatus> RunAsync(WorkflowContext context, Order order)
    {
+       // First two independent activities are called in parallel (fan-out/fan-in pattern):
        var inventoryTask = context.CallActivityAsync<ActivityResult>(
                nameof(CheckInventory),
                order.OrderItem);
@@ -22,6 +23,8 @@ public override async Task<OrderStatus> RunAsync(WorkflowContext context, Order
            return new OrderStatus(IsSuccess: false, message);
        }
 
+       // Two activities are called in sequence (chaining pattern) where the UpdateInventory
+       // activity is dependent on the result of the ProcessPayment activity:
        var paymentResult = await context.CallActivityAsync<PaymentResult>(
            nameof(ProcessPayment),
            order);
@@ -35,22 +38,26 @@ public override async Task<OrderStatus> RunAsync(WorkflowContext context, Order
        ShipmentRegistrationStatus shipmentRegistrationStatus;
        try
        {
+           // The RegisterShipment activity is using pub/sub messaging to communicate with the ShippingApp.
            await context.CallActivityAsync<RegisterShipmentResult>(
                nameof(RegisterShipment),
                order);
+           // The ShippingApp will also use pub/sub messaging back to the WorkflowApp and raise an event.
+           // The workflow will wait for the event to be received or until the timeout occurs.
            shipmentRegistrationStatus = await context.WaitForExternalEventAsync<ShipmentRegistrationStatus>(
                eventName: Constants.SHIPMENT_REGISTERED_EVENT,
                timeout: TimeSpan.FromSeconds(300));
        }
        catch (TaskCanceledException)
        {
-           // Timeout occurred
+           // Timeout occurred, the shipment-registered-event was not received.
            var message = $"ShipmentRegistrationStatus for {order.Id} timed out.";
            return new OrderStatus(IsSuccess: false, message);
        }
 
        if (!shipmentRegistrationStatus.IsSuccess)
        {
+           // This is the compensation step in case the shipment registration event was not successful.
            await context.CallActivityAsync(
                nameof(ReimburseCustomer),
                order);