Workflow.cs

[Workflow]
public class MyWorkflow
{
    [WorkflowRun]
    public async Task<MyActivities.Order> RunAsync()
    {
        var order = new MyActivities.Order(Guid.NewGuid());

        await Workflow.ExecuteActivityAsync<MyActivities>(activities => activities.PlaceOrder(order), new ActivityOptions() {
            StartToCloseTimeout = TimeSpan.FromMinutes(5),
        });
        
        var transactionId = await Workflow.ExecuteActivityAsync<MyActivities, Guid>(activities => activities.ProcessPayment(order, new MyActivities.CreditCard()), new ActivityOptions {
            StartToCloseTimeout = TimeSpan.FromMinutes(5),
        });

        Console.WriteLine($"Transaction Id: {transactionId} for Order Id {order.OrderId}");
        
        await Workflow.ExecuteActivityAsync<MyActivities>(activities => activities.EmailConfirmation(order), new ActivityOptions {
            StartToCloseTimeout = TimeSpan.FromMinutes(5),
        });
        
        Console.WriteLine("Workflow Complete");

        return order;
    }
}

public class MyActivities
{
    [Activity]
    public Task PlaceOrder(Order order)
    {
        Console.WriteLine($"Place Order Id {order.OrderId}");
        return Task.CompletedTask;
    }

    [Activity]
    public async Task<Guid> ProcessPayment(Order order, CreditCard creditCard)
    {
        Console.WriteLine($"Process Payment for Order Id {order.OrderId}");
        await Task.Delay(TimeSpan.FromSeconds(5));

        return Guid.NewGuid();
    }

    [Activity]
    public Task EmailConfirmation(Order order)
    {
        Console.WriteLine($"Email Confirmation for Order Id {order.OrderId}");
        return Task.CompletedTask;
    }
    
    public record Order(Guid OrderId);

    public record CreditCard();
}