mirror of https://github.com/dapr/docs.git
279 lines
11 KiB
Markdown
279 lines
11 KiB
Markdown
---
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type: docs
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title: "Quickstart: Workflow"
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linkTitle: Workflow
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weight: 77
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description: Get started with the Dapr Workflow building block
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---
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{{% alert title="Note" color="primary" %}}
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The workflow building block is currently in **alpha**.
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{{% /alert %}}
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Let's take a look at the Dapr [Workflow building block]({{< ref workflow >}}). In this Quickstart, you'll create a simple console application to demonstrate Dapr's workflow programming model and the workflow management APIs.
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The `order-processor` console app starts and manages the lifecycle of the `OrderProcessingWorkflow` workflow that stores and retrieves data in a state store. The workflow consists of four workflow activities, or tasks:
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- `NotifyActivity`: Utilizes a logger to print out messages throughout the workflow
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- `ReserveInventoryActivity`: Checks the state store to ensure that there is enough inventory for the purchase
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- `ProcessPaymentActivity`: Processes and authorizes the payment
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- `UpdateInventoryActivity`: Removes the requested items from the state store and updates the store with the new remaining inventory value
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In this guide, you'll:
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- Run the `order-processor` application.
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- Start the workflow and watch the workflow activites/tasks execute.
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- Review the workflow logic and the workflow activities and how they're represented in the code.
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<img src="/images/workflow-quickstart-overview.png" width=800 style="padding-bottom:15px;">
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Currently, you can experience the Dapr Workflow using the .NET SDK.
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{{< tabs ".NET" >}}
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<!-- .NET -->
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{{% codetab %}}
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### Step 1: Pre-requisites
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For this example, you will need:
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- [Dapr CLI and initialized environment](https://docs.dapr.io/getting-started).
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- [.NET SDK or .NET 6 SDK installed](https://dotnet.microsoft.com/download).
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<!-- IGNORE_LINKS -->
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- [Docker Desktop](https://www.docker.com/products/docker-desktop)
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<!-- END_IGNORE -->
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### Step 2: Set up the environment
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Clone the [sample provided in the Quickstarts repo](https://github.com/dapr/quickstarts/tree/master/workflows).
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```bash
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git clone https://github.com/dapr/quickstarts.git
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```
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In a new terminal window, navigate to the `order-processor` directory:
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```bash
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cd workflows/csharp/sdk/order-processor
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```
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### Step 3: Run the order processor app
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In the terminal, start the order processor app alongside a Dapr sidecar:
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```bash
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dapr run --app-id order-processor dotnet run
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```
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This starts the `order-processor` app with unique workflow ID and runs the workflow activities.
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Expected output:
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```
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== APP == Starting workflow 6d2abcc9 purchasing 10 Cars
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== APP == info: Microsoft.DurableTask.Client.Grpc.GrpcDurableTaskClient[40]
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== APP == Scheduling new OrderProcessingWorkflow orchestration with instance ID '6d2abcc9' and 47 bytes of input data.
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== APP == info: WorkflowConsoleApp.Activities.NotifyActivity[0]
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== APP == Received order 6d2abcc9 for 10 Cars at $15000
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== APP == info: WorkflowConsoleApp.Activities.ReserveInventoryActivity[0]
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== APP == Reserving inventory for order 6d2abcc9 of 10 Cars
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== APP == info: WorkflowConsoleApp.Activities.ReserveInventoryActivity[0]
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== APP == There are: 100, Cars available for purchase
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== APP == Your workflow has started. Here is the status of the workflow: Dapr.Workflow.WorkflowState
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== APP == info: WorkflowConsoleApp.Activities.ProcessPaymentActivity[0]
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== APP == Processing payment: 6d2abcc9 for 10 Cars at $15000
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== APP == info: WorkflowConsoleApp.Activities.ProcessPaymentActivity[0]
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== APP == Payment for request ID '6d2abcc9' processed successfully
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== APP == info: WorkflowConsoleApp.Activities.UpdateInventoryActivity[0]
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== APP == Checking Inventory for: Order# 6d2abcc9 for 10 Cars
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== APP == info: WorkflowConsoleApp.Activities.UpdateInventoryActivity[0]
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== APP == There are now: 90 Cars left in stock
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== APP == info: WorkflowConsoleApp.Activities.NotifyActivity[0]
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== APP == Order 6d2abcc9 has completed!
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== APP == Workflow Status: Completed
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```
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### (Optional) Step 4: View in Zipkin
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If you have Zipkin configured for Dapr locally on your machine, you can view the workflow trace spans in the Zipkin web UI (typically at `http://localhost:9411/zipkin/`).
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<img src="/images/workflow-trace-spans-zipkin.png" width=800 style="padding-bottom:15px;">
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### What happened?
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When you ran `dapr run --app-id order-processor dotnet run`:
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1. A unique order ID for the workflow is generated (in the above example, `6d2abcc9`) and the workflow is scheduled.
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1. The `NotifyActivity` workflow activity sends a notification saying an order for 10 cars has been received.
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1. The `ReserveInventoryActivity` workflow activity checks the inventory data, determines if you can supply the ordered item, and responds with the number of cars in stock.
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1. Your workflow starts and notifies you of its status.
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1. The `ProcessPaymentActivity` workflow activity begins processing payment for order `6d2abcc9` and confirms if successful.
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1. The `UpdateInventoryActivity` workflow activity updates the inventory with the current available cars after the order has been processed.
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1. The `NotifyActivity` workflow activity sends a notification saying that order `6d2abcc9` has completed.
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1. The workflow terminates as completed.
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#### `order-processor/Program.cs`
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In the application's program file:
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- The unique workflow order ID is generated
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- The workflow is scheduled
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- The workflow status is retrieved
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- The workflow and the workflow activities it invokes are registered
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```csharp
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using Dapr.Client;
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using Dapr.Workflow;
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//...
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{
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services.AddDaprWorkflow(options =>
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{
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// Note that it's also possible to register a lambda function as the workflow
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// or activity implementation instead of a class.
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options.RegisterWorkflow<OrderProcessingWorkflow>();
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// These are the activities that get invoked by the workflow(s).
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options.RegisterActivity<NotifyActivity>();
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options.RegisterActivity<ReserveInventoryActivity>();
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options.RegisterActivity<ProcessPaymentActivity>();
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options.RegisterActivity<UpdateInventoryActivity>();
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});
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};
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//...
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// Generate a unique ID for the workflow
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string orderId = Guid.NewGuid().ToString()[..8];
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string itemToPurchase = "Cars";
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int ammountToPurchase = 10;
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//...
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// Start the workflow
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Console.WriteLine("Starting workflow {0} purchasing {1} {2}", orderId, ammountToPurchase, itemToPurchase);
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await workflowClient.ScheduleNewWorkflowAsync(
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name: nameof(OrderProcessingWorkflow),
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instanceId: orderId,
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input: orderInfo);
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//...
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WorkflowState state = await workflowClient.GetWorkflowStateAsync(
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instanceId: orderId,
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getInputsAndOutputs: true);
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Console.WriteLine("Your workflow has started. Here is the status of the workflow: {0}", state);
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//...
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Console.WriteLine("Workflow Status: {0}", state.RuntimeStatus);
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```
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#### `order-processor/Workflows/OrderProcessingWorkflow.cs`
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In `OrderProcessingWorkflow.cs`, the workflow is defined as a class with all of its associated tasks (determined by workflow activities).
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```csharp
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using Dapr.Workflow;
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//...
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class OrderProcessingWorkflow : Workflow<OrderPayload, OrderResult>
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{
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public override async Task<OrderResult> RunAsync(WorkflowContext context, OrderPayload order)
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{
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string orderId = context.InstanceId;
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// Notify the user that an order has come through
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await context.CallActivityAsync(
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nameof(NotifyActivity),
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new Notification($"Received order {orderId} for {order.Quantity} {order.Name} at ${order.TotalCost}"));
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string requestId = context.InstanceId;
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// Determine if there is enough of the item available for purchase by checking the inventory
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InventoryResult result = await context.CallActivityAsync<InventoryResult>(
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nameof(ReserveInventoryActivity),
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new InventoryRequest(RequestId: orderId, order.Name, order.Quantity));
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// If there is insufficient inventory, fail and let the user know
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if (!result.Success)
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{
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// End the workflow here since we don't have sufficient inventory
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await context.CallActivityAsync(
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nameof(NotifyActivity),
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new Notification($"Insufficient inventory for {order.Name}"));
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return new OrderResult(Processed: false);
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}
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// There is enough inventory available so the user can purchase the item(s). Process their payment
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await context.CallActivityAsync(
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nameof(ProcessPaymentActivity),
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new PaymentRequest(RequestId: orderId, order.Name, order.Quantity, order.TotalCost));
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try
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{
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// There is enough inventory available so the user can purchase the item(s). Process their payment
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await context.CallActivityAsync(
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nameof(UpdateInventoryActivity),
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new PaymentRequest(RequestId: orderId, order.Name, order.Quantity, order.TotalCost));
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}
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catch (TaskFailedException)
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{
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// Let them know their payment was processed
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await context.CallActivityAsync(
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nameof(NotifyActivity),
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new Notification($"Order {orderId} Failed! You are now getting a refund"));
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return new OrderResult(Processed: false);
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}
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// Let them know their payment was processed
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await context.CallActivityAsync(
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nameof(NotifyActivity),
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new Notification($"Order {orderId} has completed!"));
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// End the workflow with a success result
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return new OrderResult(Processed: true);
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}
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}
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```
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#### `order-processor/Activities` directory
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The `Activities` directory holds the four workflow activities used by the workflow, defined in the following files:
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- `NotifyActivity.cs`
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- `ReserveInventoryActivity.cs`
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- `ProcessPaymentActivity.cs`
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- `UpdateInventoryActivity.cs`
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{{% /codetab %}}
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{{< /tabs >}}
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## Watch the demo
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Watch [this video to walk through the Dapr Workflow .NET demo](https://youtu.be/BxiKpEmchgQ?t=2564):
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<iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/BxiKpEmchgQ?start=2564" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>
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## Tell us what you think!
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We're continuously working to improve our Quickstart examples and value your feedback. Did you find this Quickstart helpful? Do you have suggestions for improvement?
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Join the discussion in our [discord channel](https://discord.com/channels/778680217417809931/953427615916638238).
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## Next steps
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- Set up Dapr Workflow with any programming language using [HTTP instead of an SDK]({{< ref howto-manage-workflow.md >}})
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- Walk through a more in-depth [.NET SDK example workflow](https://github.com/dapr/dotnet-sdk/tree/master/examples/Workflow)
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- Learn more about [Workflow as a Dapr building block]({{< ref workflow-overview >}})
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{{< button text="Explore Dapr tutorials >>" page="getting-started/tutorials/_index.md" >}}
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