Quickstart: Workflow

git clone https://github.com/dapr/quickstarts.git

cd workflows/csharp/sdk/order-processor

dapr run --app-id order-processor dotnet run

using Dapr.Client;
using Dapr.Workflow;
//...

{
    services.AddDaprWorkflow(options =>
    {
        // Note that it's also possible to register a lambda function as the workflow
        // or activity implementation instead of a class.
        options.RegisterWorkflow<OrderProcessingWorkflow>();

        // These are the activities that get invoked by the workflow(s).
        options.RegisterActivity<NotifyActivity>();
        options.RegisterActivity<ReserveInventoryActivity>();
        options.RegisterActivity<ProcessPaymentActivity>();
        options.RegisterActivity<UpdateInventoryActivity>();
    });
};

//...

// Generate a unique ID for the workflow
string orderId = Guid.NewGuid().ToString()[..8];
string itemToPurchase = "Cars";
int ammountToPurchase = 10;

//...

// Start the workflow
Console.WriteLine("Starting workflow {0} purchasing {1} {2}", orderId, ammountToPurchase, itemToPurchase);

await workflowClient.ScheduleNewWorkflowAsync(
    name: nameof(OrderProcessingWorkflow),
    instanceId: orderId,
    input: orderInfo);

//...

WorkflowState state = await workflowClient.GetWorkflowStateAsync(
    instanceId: orderId,
    getInputsAndOutputs: true);

Console.WriteLine("Your workflow has started. Here is the status of the workflow: {0}", state);

//...

Console.WriteLine("Workflow Status: {0}", state.RuntimeStatus);

using Dapr.Workflow;
//...

class OrderProcessingWorkflow : Workflow<OrderPayload, OrderResult>
    {
        public override async Task<OrderResult> RunAsync(WorkflowContext context, OrderPayload order)
        {
            string orderId = context.InstanceId;

            // Notify the user that an order has come through
            await context.CallActivityAsync(
                nameof(NotifyActivity),
                new Notification($"Received order {orderId} for {order.Quantity} {order.Name} at ${order.TotalCost}"));

            string requestId = context.InstanceId;

            // Determine if there is enough of the item available for purchase by checking the inventory
            InventoryResult result = await context.CallActivityAsync<InventoryResult>(
                nameof(ReserveInventoryActivity),
                new InventoryRequest(RequestId: orderId, order.Name, order.Quantity));

            // If there is insufficient inventory, fail and let the user know 
            if (!result.Success)
            {
                // End the workflow here since we don't have sufficient inventory
                await context.CallActivityAsync(
                    nameof(NotifyActivity),
                    new Notification($"Insufficient inventory for {order.Name}"));
                return new OrderResult(Processed: false);
            }

            // There is enough inventory available so the user can purchase the item(s). Process their payment
            await context.CallActivityAsync(
                nameof(ProcessPaymentActivity),
                new PaymentRequest(RequestId: orderId, order.Name, order.Quantity, order.TotalCost));

            try
            {
                // There is enough inventory available so the user can purchase the item(s). Process their payment
                await context.CallActivityAsync(
                    nameof(UpdateInventoryActivity),
                    new PaymentRequest(RequestId: orderId, order.Name, order.Quantity, order.TotalCost));                
            }
            catch (TaskFailedException)
            {
                // Let them know their payment was processed
                await context.CallActivityAsync(
                    nameof(NotifyActivity),
                    new Notification($"Order {orderId} Failed! You are now getting a refund"));
                return new OrderResult(Processed: false);
            }

            // Let them know their payment was processed
            await context.CallActivityAsync(
                nameof(NotifyActivity),
                new Notification($"Order {orderId} has completed!"));

            // End the workflow with a success result
            return new OrderResult(Processed: true);
        }
    }