Quickstart: Workflow

Get started with the Dapr Workflow building block

Let’s take a look at the Dapr Workflow building block. In this Quickstart, you’ll create a simple console application to demonstrate Dapr’s workflow programming model and the workflow management APIs.

In this guide, you’ll:

  • Run the order-processor application.
  • Start the workflow and watch the workflow activites/tasks execute.
  • Review the workflow logic and the workflow activities and how they’re represented in the code.

Select your preferred language-specific Dapr SDK before proceeding with the Quickstart.


The order-processor console app starts and manages the order_processing_workflow, which simulates purchasing items from a store. The workflow consists of five unique workflow activities, or tasks:

  • notify_activity: Utilizes a logger to print out messages throughout the workflow. These messages notify you when:
    • You have insufficient inventory
    • Your payment couldn’t be processed, etc.
  • process_payment_activity: Processes and authorizes the payment.
  • verify_inventory_activity: Checks the state store to ensure there is enough inventory present for purchase.
  • update_inventory_activity: Removes the requested items from the state store and updates the store with the new remaining inventory value.
  • request_approval_activity: Seeks approval from the manager if payment is greater than 50,000 USD.

Step 1: Pre-requisites

For this example, you will need:

Step 2: Set up the environment

Clone the sample provided in the Quickstarts repo.

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

In a new terminal window, navigate to the order-processor directory:

cd workflows/python/sdk/order-processor

Install the Dapr Python SDK package:

pip3 install -r requirements.txt

Step 3: Run the order processor app

In the terminal, start the order processor app alongside a Dapr sidecar using Multi-App Run:

dapr run -f .

This starts the order-processor app with unique workflow ID and runs the workflow activities.

Expected output:

== APP == Starting order workflow, purchasing 10 of cars
== APP == 2023-06-06 09:35:52.945 durabletask-worker INFO: Successfully connected to 127.0.0.1:65406. Waiting for work items...
== APP == INFO:NotifyActivity:Received order f4e1926e-3721-478d-be8a-f5bebd1995da for 10 cars at $150000 !
== APP == INFO:VerifyInventoryActivity:Verifying inventory for order f4e1926e-3721-478d-be8a-f5bebd1995da of 10 cars
== APP == INFO:VerifyInventoryActivity:There are 100 Cars available for purchase
== APP == INFO:RequestApprovalActivity:Requesting approval for payment of 165000 USD for 10 cars
== APP == 2023-06-06 09:36:05.969 durabletask-worker INFO: f4e1926e-3721-478d-be8a-f5bebd1995da Event raised: manager_approval
== APP == INFO:NotifyActivity:Payment for order f4e1926e-3721-478d-be8a-f5bebd1995da has been approved!
== APP == INFO:ProcessPaymentActivity:Processing payment: f4e1926e-3721-478d-be8a-f5bebd1995da for 10 cars at 150000 USD
== APP == INFO:ProcessPaymentActivity:Payment for request ID f4e1926e-3721-478d-be8a-f5bebd1995da processed successfully
== APP == INFO:UpdateInventoryActivity:Checking inventory for order f4e1926e-3721-478d-be8a-f5bebd1995da for 10 cars
== APP == INFO:UpdateInventoryActivity:There are now 90 cars left in stock
== APP == INFO:NotifyActivity:Order f4e1926e-3721-478d-be8a-f5bebd1995da has completed!
== APP == 2023-06-06 09:36:06.106 durabletask-worker INFO: f4e1926e-3721-478d-be8a-f5bebd1995da: Orchestration completed with status: COMPLETED
== APP == Workflow completed! Result: Completed
== APP == Purchase of item is  Completed

(Optional) Step 4: View in Zipkin

Running dapr init launches the openzipkin/zipkin Docker container. If the container has stopped running, launch the Zipkin Docker container with the following command:

docker run -d -p 9411:9411 openzipkin/zipkin

View the workflow trace spans in the Zipkin web UI (typically at http://localhost:9411/zipkin/).

What happened?

When you ran dapr run --app-id order-processor --resources-path ../../../components/ -- python3 app.py:

  1. A unique order ID for the workflow is generated (in the above example, f4e1926e-3721-478d-be8a-f5bebd1995da) and the workflow is scheduled.
  2. The NotifyActivity workflow activity sends a notification saying an order for 10 cars has been received.
  3. 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.
  4. Your workflow starts and notifies you of its status.
  5. The ProcessPaymentActivity workflow activity begins processing payment for order f4e1926e-3721-478d-be8a-f5bebd1995da and confirms if successful.
  6. The UpdateInventoryActivity workflow activity updates the inventory with the current available cars after the order has been processed.
  7. The NotifyActivity workflow activity sends a notification saying that order f4e1926e-3721-478d-be8a-f5bebd1995da has completed.
  8. The workflow terminates as completed.

order-processor/app.py

In the application’s program file:

  • The unique workflow order ID is generated
  • The workflow is scheduled
  • The workflow status is retrieved
  • The workflow and the workflow activities it invokes are registered
class WorkflowConsoleApp:    
    def main(self):
        # Register workflow and activities
        workflowRuntime = WorkflowRuntime(settings.DAPR_RUNTIME_HOST, settings.DAPR_GRPC_PORT)
        workflowRuntime.register_workflow(order_processing_workflow)
        workflowRuntime.register_activity(notify_activity)
        workflowRuntime.register_activity(requst_approval_activity)
        workflowRuntime.register_activity(verify_inventory_activity)
        workflowRuntime.register_activity(process_payment_activity)
        workflowRuntime.register_activity(update_inventory_activity)
        workflowRuntime.start()

        print("==========Begin the purchase of item:==========", flush=True)
        item_name = default_item_name
        order_quantity = 10

        total_cost = int(order_quantity) * baseInventory[item_name].per_item_cost
        order = OrderPayload(item_name=item_name, quantity=int(order_quantity), total_cost=total_cost)

        # Start Workflow
        print(f'Starting order workflow, purchasing {order_quantity} of {item_name}', flush=True)
        start_resp = daprClient.start_workflow(workflow_component=workflow_component,
                                               workflow_name=workflow_name,
                                               input=order)
        _id = start_resp.instance_id

        def prompt_for_approval(daprClient: DaprClient):
            daprClient.raise_workflow_event(instance_id=_id, workflow_component=workflow_component, 
                                            event_name="manager_approval", event_data={'approval': True})

        approval_seeked = False
        start_time = datetime.now()
        while True:
            time_delta = datetime.now() - start_time
            state = daprClient.get_workflow(instance_id=_id, workflow_component=workflow_component)
            if not state:
                print("Workflow not found!")  # not expected
            elif state.runtime_status == "Completed" or\
                    state.runtime_status == "Failed" or\
                    state.runtime_status == "Terminated":
                print(f'Workflow completed! Result: {state.runtime_status}', flush=True)
                break
            if time_delta.total_seconds() >= 10:
                state = daprClient.get_workflow(instance_id=_id, workflow_component=workflow_component)
                if total_cost > 50000 and (
                    state.runtime_status != "Completed" or 
                    state.runtime_status != "Failed" or
                    state.runtime_status != "Terminated"
                    ) and not approval_seeked:
                    approval_seeked = True
                    threading.Thread(target=prompt_for_approval(daprClient), daemon=True).start()
            
        print("Purchase of item is ", state.runtime_status, flush=True)

    def restock_inventory(self, daprClient: DaprClient, baseInventory):
        for key, item in baseInventory.items():
            print(f'item: {item}')
            item_str = f'{{"name": "{item.item_name}", "quantity": {item.quantity},\
                          "per_item_cost": {item.per_item_cost}}}'
            daprClient.save_state("statestore-actors", key, item_str)

if __name__ == '__main__':
    app = WorkflowConsoleApp()
    app.main()

order-processor/workflow.py

In workflow.py, the workflow is defined as a class with all of its associated tasks (determined by workflow activities).

  def order_processing_workflow(ctx: DaprWorkflowContext, order_payload_str: OrderPayload):
    """Defines the order processing workflow.
    When the order is received, the inventory is checked to see if there is enough inventory to
    fulfill the order. If there is enough inventory, the payment is processed and the inventory is
    updated. If there is not enough inventory, the order is rejected.
    If the total order is greater than $50,000, the order is sent to a manager for approval.
    """
    order_id = ctx.instance_id
    order_payload=json.loads(order_payload_str)
    yield ctx.call_activity(notify_activity, 
                            input=Notification(message=('Received order ' +order_id+ ' for '
                                               +f'{order_payload["quantity"]}' +' ' +f'{order_payload["item_name"]}'
                                               +' at $'+f'{order_payload["total_cost"]}' +' !')))
    result = yield ctx.call_activity(verify_inventory_activity,
                                     input=InventoryRequest(request_id=order_id,
                                                            item_name=order_payload["item_name"],
                                                            quantity=order_payload["quantity"]))
    if not result.success:
        yield ctx.call_activity(notify_activity,
                                input=Notification(message='Insufficient inventory for '
                                                   +f'{order_payload["item_name"]}'+'!'))
        return OrderResult(processed=False)
    
    if order_payload["total_cost"] > 50000:
        yield ctx.call_activity(requst_approval_activity, input=order_payload)
        approval_task = ctx.wait_for_external_event("manager_approval")
        timeout_event = ctx.create_timer(timedelta(seconds=200))
        winner = yield when_any([approval_task, timeout_event])
        if winner == timeout_event:
            yield ctx.call_activity(notify_activity, 
                                    input=Notification(message='Payment for order '+order_id
                                                       +' has been cancelled due to timeout!'))
            return OrderResult(processed=False)
        approval_result = yield approval_task
        if approval_result["approval"]:
            yield ctx.call_activity(notify_activity, input=Notification(
                message=f'Payment for order {order_id} has been approved!'))
        else:
            yield ctx.call_activity(notify_activity, input=Notification(
                message=f'Payment for order {order_id} has been rejected!'))
            return OrderResult(processed=False)    
    
    yield ctx.call_activity(process_payment_activity, input=PaymentRequest(
        request_id=order_id, item_being_purchased=order_payload["item_name"],
        amount=order_payload["total_cost"], quantity=order_payload["quantity"]))

    try:
        yield ctx.call_activity(update_inventory_activity, 
                                input=PaymentRequest(request_id=order_id,
                                                     item_being_purchased=order_payload["item_name"],
                                                     amount=order_payload["total_cost"],
                                                     quantity=order_payload["quantity"]))
    except Exception:
        yield ctx.call_activity(notify_activity, 
                                input=Notification(message=f'Order {order_id} Failed!'))
        return OrderResult(processed=False)

    yield ctx.call_activity(notify_activity, input=Notification(
        message=f'Order {order_id} has completed!'))
    return OrderResult(processed=True) 

The order-processor console app starts and manages the lifecycle of an order processing workflow that stores and retrieves data in a state store. The workflow consists of four workflow activities, or tasks:

  • NotifyActivity: Utilizes a logger to print out messages throughout the workflow
  • ReserveInventoryActivity: Checks the state store to ensure that there is enough inventory for the purchase
  • ProcessPaymentActivity: Processes and authorizes the payment
  • UpdateInventoryActivity: Removes the requested items from the state store and updates the store with the new remaining inventory value

Step 1: Pre-requisites

For this example, you will need:

Step 2: Set up the environment

Clone the sample provided in the Quickstarts repo.

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

In a new terminal window, navigate to the order-processor directory:

cd workflows/javascript/sdk/order-processor

Step 3: Run the order processor app

In the terminal, start the order processor app alongside a Dapr sidecar:

dapr run 

This starts the order-processor app with unique workflow ID and runs the workflow activities.

Expected output:

(Optional) Step 4: View in Zipkin

Running dapr init launches the openzipkin/zipkin Docker container. If the container has stopped running, launch the Zipkin Docker container with the following command:

docker run -d -p 9411:9411 openzipkin/zipkin

View the workflow trace spans in the Zipkin web UI (typically at http://localhost:9411/zipkin/).

What happened?

When you ran dapr run :

  1. A unique order ID for the workflow is generated (in the above example, 6d2abcc9) and the workflow is scheduled.
  2. The NotifyActivity workflow activity sends a notification saying an order for 10 cars has been received.
  3. 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.
  4. Your workflow starts and notifies you of its status.
  5. The ProcessPaymentActivity workflow activity begins processing payment for order 6d2abcc9 and confirms if successful.
  6. The UpdateInventoryActivity workflow activity updates the inventory with the current available cars after the order has been processed.
  7. The NotifyActivity workflow activity sends a notification saying that order 6d2abcc9 has completed.
  8. The workflow terminates as completed.

order-processor/index.js

In the application’s program file:

  • The unique workflow order ID is generated
  • The workflow is scheduled
  • The workflow status is retrieved
  • The workflow and the workflow activities it invokes are registered

order-processor/Workflows/OrderProcessingWorkflow.js

In OrderProcessingWorkflow.js, the workflow is defined as a class with all of its associated tasks (determined by workflow activities).

order-processor/Activities directory

The Activities directory holds the four workflow activities used by the workflow, defined in the following files:


The order-processor console app starts and manages the lifecycle of an order processing workflow that stores and retrieves data in a state store. The workflow consists of four workflow activities, or tasks:

  • NotifyActivity: Utilizes a logger to print out messages throughout the workflow
  • ReserveInventoryActivity: Checks the state store to ensure that there is enough inventory for the purchase
  • ProcessPaymentActivity: Processes and authorizes the payment
  • UpdateInventoryActivity: Removes the requested items from the state store and updates the store with the new remaining inventory value

Step 1: Pre-requisites

For this example, you will need:

Step 2: Set up the environment

Clone the sample provided in the Quickstarts repo.

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

In a new terminal window, navigate to the order-processor directory:

cd workflows/csharp/sdk/order-processor

Step 3: Run the order processor app

In the terminal, start the order processor app alongside a Dapr sidecar using Multi-App Run:

dapr run -f .

This starts the order-processor app with unique workflow ID and runs the workflow activities.

Expected output:

== APP == Starting workflow 6d2abcc9 purchasing 10 Cars

== APP == info: Microsoft.DurableTask.Client.Grpc.GrpcDurableTaskClient[40]
== APP ==       Scheduling new OrderProcessingWorkflow orchestration with instance ID '6d2abcc9' and 47 bytes of input data.
== APP == info: WorkflowConsoleApp.Activities.NotifyActivity[0]
== APP ==       Received order 6d2abcc9 for 10 Cars at $15000
== APP == info: WorkflowConsoleApp.Activities.ReserveInventoryActivity[0]
== APP ==       Reserving inventory for order 6d2abcc9 of 10 Cars
== APP == info: WorkflowConsoleApp.Activities.ReserveInventoryActivity[0]
== APP ==       There are: 100, Cars available for purchase

== APP == Your workflow has started. Here is the status of the workflow: Dapr.Workflow.WorkflowState

== APP == info: WorkflowConsoleApp.Activities.ProcessPaymentActivity[0]
== APP ==       Processing payment: 6d2abcc9 for 10 Cars at $15000
== APP == info: WorkflowConsoleApp.Activities.ProcessPaymentActivity[0]
== APP ==       Payment for request ID '6d2abcc9' processed successfully
== APP == info: WorkflowConsoleApp.Activities.UpdateInventoryActivity[0]
== APP ==       Checking Inventory for: Order# 6d2abcc9 for 10 Cars
== APP == info: WorkflowConsoleApp.Activities.UpdateInventoryActivity[0]
== APP ==       There are now: 90 Cars left in stock
== APP == info: WorkflowConsoleApp.Activities.NotifyActivity[0]
== APP ==       Order 6d2abcc9 has completed!

== APP == Workflow Status: Completed

(Optional) Step 4: View in Zipkin

Running dapr init launches the openzipkin/zipkin Docker container. If the container has stopped running, launch the Zipkin Docker container with the following command:

docker run -d -p 9411:9411 openzipkin/zipkin

View the workflow trace spans in the Zipkin web UI (typically at http://localhost:9411/zipkin/).

What happened?

When you ran dapr run --app-id order-processor dotnet run:

  1. A unique order ID for the workflow is generated (in the above example, 6d2abcc9) and the workflow is scheduled.
  2. The NotifyActivity workflow activity sends a notification saying an order for 10 cars has been received.
  3. 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.
  4. Your workflow starts and notifies you of its status.
  5. The ProcessPaymentActivity workflow activity begins processing payment for order 6d2abcc9 and confirms if successful.
  6. The UpdateInventoryActivity workflow activity updates the inventory with the current available cars after the order has been processed.
  7. The NotifyActivity workflow activity sends a notification saying that order 6d2abcc9 has completed.
  8. The workflow terminates as completed.

order-processor/Program.cs

In the application’s program file:

  • The unique workflow order ID is generated
  • The workflow is scheduled
  • The workflow status is retrieved
  • The workflow and the workflow activities it invokes are registered
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;

// Construct the order
OrderPayload orderInfo = new OrderPayload(itemToPurchase, 15000, ammountToPurchase);

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

await daprClient.StartWorkflowAsync(
    workflowComponent: DaprWorkflowComponent,
    workflowName: nameof(OrderProcessingWorkflow),
    input: orderInfo,
    instanceId: orderId);

// Wait for the workflow to start and confirm the input
GetWorkflowResponse state = await daprClient.WaitForWorkflowStartAsync(
    instanceId: orderId,
    workflowComponent: DaprWorkflowComponent);

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

// Wait for the workflow to complete
state = await daprClient.WaitForWorkflowCompletionAsync(
    instanceId: orderId,
    workflowComponent: DaprWorkflowComponent);

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

order-processor/Workflows/OrderProcessingWorkflow.cs

In OrderProcessingWorkflow.cs, the workflow is defined as a class with all of its associated tasks (determined by workflow activities).

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);
        }
    }

order-processor/Activities directory

The Activities directory holds the four workflow activities used by the workflow, defined in the following files:

  • NotifyActivity.cs
  • ReserveInventoryActivity.cs
  • ProcessPaymentActivity.cs
  • UpdateInventoryActivity.cs

Watch the demo

Watch this video to walk through the Dapr Workflow .NET demo:


The order-processor console app starts and manages the lifecycle of an order processing workflow that stores and retrieves data in a state store. The workflow consists of four workflow activities, or tasks:

  • NotifyActivity: Utilizes a logger to print out messages throughout the workflow
  • RequestApprovalActivity: Requests approval for processing payment
  • ReserveInventoryActivity: Checks the state store to ensure that there is enough inventory for the purchase
  • ProcessPaymentActivity: Processes and authorizes the payment
  • UpdateInventoryActivity: Removes the requested items from the state store and updates the store with the new remaining inventory value

Step 1: Pre-requisites

For this example, you will need:

Step 2: Set up the environment

Clone the sample provided in the Quickstarts repo.

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

Navigate to the order-processor directory:

cd workflows/java/sdk/order-processor

Install the dependencies:

mvn clean install

Step 3: Run the order processor app

In the terminal, start the order processor app alongside a Dapr sidecar using Multi-App Run:

dapr run -f .

This starts the order-processor app with unique workflow ID and runs the workflow activities.

Expected output:

== APP == *** Welcome to the Dapr Workflow console app sample!
== APP == *** Using this app, you can place orders that start workflows.
== APP == Start workflow runtime
== APP == Sep 20, 2023 3:23:05 PM com.microsoft.durabletask.DurableTaskGrpcWorker startAndBlock
== APP == INFO: Durable Task worker is connecting to sidecar at 127.0.0.1:50001.

== APP == ==========Begin the purchase of item:==========
== APP == Starting order workflow, purchasing 10 of cars

== APP == scheduled new workflow instance of OrderProcessingWorkflow with instance ID: edceba90-9c45-4be8-ad40-60d16e060797
== APP == [Thread-0] INFO io.dapr.workflows.WorkflowContext - Starting Workflow: io.dapr.quickstarts.workflows.OrderProcessingWorkflow
== APP == [Thread-0] INFO io.dapr.workflows.WorkflowContext - Instance ID(order ID): edceba90-9c45-4be8-ad40-60d16e060797
== APP == [Thread-0] INFO io.dapr.workflows.WorkflowContext - Current Orchestration Time: 2023-09-20T19:23:09.755Z
== APP == [Thread-0] INFO io.dapr.workflows.WorkflowContext - Received Order: OrderPayload [itemName=cars, totalCost=150000, quantity=10]
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.NotifyActivity - Received Order: OrderPayload [itemName=cars, totalCost=150000, quantity=10]
== APP == workflow instance edceba90-9c45-4be8-ad40-60d16e060797 started
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.ReserveInventoryActivity - Reserving inventory for order 'edceba90-9c45-4be8-ad40-60d16e060797' of 10 cars
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.ReserveInventoryActivity - There are 100 cars available for purchase
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.ReserveInventoryActivity - Reserved inventory for order 'edceba90-9c45-4be8-ad40-60d16e060797' of 10 cars
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.RequestApprovalActivity - Requesting approval for order: OrderPayload [itemName=cars, totalCost=150000, quantity=10]
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.RequestApprovalActivity - Approved requesting approval for order: OrderPayload [itemName=cars, totalCost=150000, quantity=10]
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.ProcessPaymentActivity - Processing payment: edceba90-9c45-4be8-ad40-60d16e060797 for 10 cars at $150000
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.ProcessPaymentActivity - Payment for request ID 'edceba90-9c45-4be8-ad40-60d16e060797' processed successfully
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.UpdateInventoryActivity - Updating inventory for order 'edceba90-9c45-4be8-ad40-60d16e060797' of 10 cars
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.UpdateInventoryActivity - Updated inventory for order 'edceba90-9c45-4be8-ad40-60d16e060797': there are now 90 cars left in stock
== APP == [Thread-0] INFO io.dapr.quickstarts.workflows.activities.NotifyActivity - Order completed! : edceba90-9c45-4be8-ad40-60d16e060797

== APP == workflow instance edceba90-9c45-4be8-ad40-60d16e060797 completed, out is: {"processed":true}

(Optional) Step 4: View in Zipkin

Running dapr init launches the openzipkin/zipkin Docker container. If the container has stopped running, launch the Zipkin Docker container with the following command:

docker run -d -p 9411:9411 openzipkin/zipkin

View the workflow trace spans in the Zipkin web UI (typically at http://localhost:9411/zipkin/).

What happened?

When you ran dapr run:

  1. A unique order ID for the workflow is generated (in the above example, edceba90-9c45-4be8-ad40-60d16e060797) and the workflow is scheduled.
  2. The NotifyActivity workflow activity sends a notification saying an order for 10 cars has been received.
  3. 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.
  4. Once approved, your workflow starts and notifies you of its status.
  5. The ProcessPaymentActivity workflow activity begins processing payment for order edceba90-9c45-4be8-ad40-60d16e060797 and confirms if successful.
  6. The UpdateInventoryActivity workflow activity updates the inventory with the current available cars after the order has been processed.
  7. The NotifyActivity workflow activity sends a notification saying that order edceba90-9c45-4be8-ad40-60d16e060797 has completed.
  8. The workflow terminates as completed.

order-processor/WorkflowConsoleApp.java

In the application’s program file:

  • The unique workflow order ID is generated
  • The workflow is scheduled
  • The workflow status is retrieved
  • The workflow and the workflow activities it invokes are registered
package io.dapr.quickstarts.workflows;
import io.dapr.client.DaprClient;
import io.dapr.client.DaprClientBuilder;
import io.dapr.workflows.client.DaprWorkflowClient;

public class WorkflowConsoleApp {

  private static final String STATE_STORE_NAME = "statestore-actors";

  // ...
  public static void main(String[] args) throws Exception {
    System.out.println("*** Welcome to the Dapr Workflow console app sample!");
    System.out.println("*** Using this app, you can place orders that start workflows.");
    // Wait for the sidecar to become available
    Thread.sleep(5 * 1000);

    // Register the OrderProcessingWorkflow and its activities with the builder.
    WorkflowRuntimeBuilder builder = new WorkflowRuntimeBuilder().registerWorkflow(OrderProcessingWorkflow.class);
    builder.registerActivity(NotifyActivity.class);
    builder.registerActivity(ProcessPaymentActivity.class);
    builder.registerActivity(RequestApprovalActivity.class);
    builder.registerActivity(ReserveInventoryActivity.class);
    builder.registerActivity(UpdateInventoryActivity.class);

    // Build the workflow runtime
    try (WorkflowRuntime runtime = builder.build()) {
      System.out.println("Start workflow runtime");
      runtime.start(false);
    }

    InventoryItem inventory = prepareInventoryAndOrder();

    DaprWorkflowClient workflowClient = new DaprWorkflowClient();
    try (workflowClient) {
      executeWorkflow(workflowClient, inventory);
    }

  }

  // Start the workflow runtime, pulling and executing tasks
  private static void executeWorkflow(DaprWorkflowClient workflowClient, InventoryItem inventory) {
    System.out.println("==========Begin the purchase of item:==========");
    String itemName = inventory.getName();
    int orderQuantity = inventory.getQuantity();
    int totalcost = orderQuantity * inventory.getPerItemCost();
    OrderPayload order = new OrderPayload();
    order.setItemName(itemName);
    order.setQuantity(orderQuantity);
    order.setTotalCost(totalcost);
    System.out.println("Starting order workflow, purchasing " + orderQuantity + " of " + itemName);

    String instanceId = workflowClient.scheduleNewWorkflow(OrderProcessingWorkflow.class, order);
    System.out.printf("scheduled new workflow instance of OrderProcessingWorkflow with instance ID: %s%n",
        instanceId);

    // Check workflow instance start status
    try {
      workflowClient.waitForInstanceStart(instanceId, Duration.ofSeconds(10), false);
      System.out.printf("workflow instance %s started%n", instanceId);
    } catch (TimeoutException e) {
      System.out.printf("workflow instance %s did not start within 10 seconds%n", instanceId);
      return;
    }

    // Check workflow instance complete status
    try {
      WorkflowInstanceStatus workflowStatus = workflowClient.waitForInstanceCompletion(instanceId,
          Duration.ofSeconds(30),
          true);
      if (workflowStatus != null) {
        System.out.printf("workflow instance %s completed, out is: %s %n", instanceId,
            workflowStatus.getSerializedOutput());
      } else {
        System.out.printf("workflow instance %s not found%n", instanceId);
      }
    } catch (TimeoutException e) {
      System.out.printf("workflow instance %s did not complete within 30 seconds%n", instanceId);
    }

  }

  private static InventoryItem prepareInventoryAndOrder() {
    // prepare 100 cars in inventory
    InventoryItem inventory = new InventoryItem();
    inventory.setName("cars");
    inventory.setPerItemCost(15000);
    inventory.setQuantity(100);
    DaprClient daprClient = new DaprClientBuilder().build();
    restockInventory(daprClient, inventory);

    // prepare order for 10 cars
    InventoryItem order = new InventoryItem();
    order.setName("cars");
    order.setPerItemCost(15000);
    order.setQuantity(10);
    return order;
  }

  private static void restockInventory(DaprClient daprClient, InventoryItem inventory) {
    String key = inventory.getName();
    daprClient.saveState(STATE_STORE_NAME, key, inventory).block();
  }
}

OrderProcessingWorkflow.java

In OrderProcessingWorkflow.java, the workflow is defined as a class with all of its associated tasks (determined by workflow activities).

package io.dapr.quickstarts.workflows;
import io.dapr.workflows.Workflow;

public class OrderProcessingWorkflow extends Workflow {

  @Override
  public WorkflowStub create() {
    return ctx -> {
      Logger logger = ctx.getLogger();
      String orderId = ctx.getInstanceId();
      logger.info("Starting Workflow: " + ctx.getName());
      logger.info("Instance ID(order ID): " + orderId);
      logger.info("Current Orchestration Time: " + ctx.getCurrentInstant());

      OrderPayload order = ctx.getInput(OrderPayload.class);
      logger.info("Received Order: " + order.toString());
      OrderResult orderResult = new OrderResult();
      orderResult.setProcessed(false);

      // Notify the user that an order has come through
      Notification notification = new Notification();
      notification.setMessage("Received Order: " + order.toString());
      ctx.callActivity(NotifyActivity.class.getName(), notification).await();

      // Determine if there is enough of the item available for purchase by checking
      // the inventory
      InventoryRequest inventoryRequest = new InventoryRequest();
      inventoryRequest.setRequestId(orderId);
      inventoryRequest.setItemName(order.getItemName());
      inventoryRequest.setQuantity(order.getQuantity());
      InventoryResult inventoryResult = ctx.callActivity(ReserveInventoryActivity.class.getName(),
          inventoryRequest, InventoryResult.class).await();

      // If there is insufficient inventory, fail and let the user know
      if (!inventoryResult.isSuccess()) {
        notification.setMessage("Insufficient inventory for order : " + order.getItemName());
        ctx.callActivity(NotifyActivity.class.getName(), notification).await();
        ctx.complete(orderResult);
        return;
      }

      // Require orders over a certain threshold to be approved
      if (order.getTotalCost() > 5000) {
        ApprovalResult approvalResult = ctx.callActivity(RequestApprovalActivity.class.getName(),
            order, ApprovalResult.class).await();
        if (approvalResult != ApprovalResult.Approved) {
          notification.setMessage("Order " + order.getItemName() + " was not approved.");
          ctx.callActivity(NotifyActivity.class.getName(), notification).await();
          ctx.complete(orderResult);
          return;
        }
      }

      // There is enough inventory available so the user can purchase the item(s).
      // Process their payment
      PaymentRequest paymentRequest = new PaymentRequest();
      paymentRequest.setRequestId(orderId);
      paymentRequest.setItemBeingPurchased(order.getItemName());
      paymentRequest.setQuantity(order.getQuantity());
      paymentRequest.setAmount(order.getTotalCost());
      boolean isOK = ctx.callActivity(ProcessPaymentActivity.class.getName(),
          paymentRequest, boolean.class).await();
      if (!isOK) {
        notification.setMessage("Payment failed for order : " + orderId);
        ctx.callActivity(NotifyActivity.class.getName(), notification).await();
        ctx.complete(orderResult);
        return;
      }

      inventoryResult = ctx.callActivity(UpdateInventoryActivity.class.getName(),
          inventoryRequest, InventoryResult.class).await();
      if (!inventoryResult.isSuccess()) {
        // If there is an error updating the inventory, refund the user
        // paymentRequest.setAmount(-1 * paymentRequest.getAmount());
        // ctx.callActivity(ProcessPaymentActivity.class.getName(),
        // paymentRequest).await();

        // Let users know their payment processing failed
        notification.setMessage("Order failed to update inventory! : " + orderId);
        ctx.callActivity(NotifyActivity.class.getName(), notification).await();
        ctx.complete(orderResult);
        return;
      }

      // Let user know their order was processed
      notification.setMessage("Order completed! : " + orderId);
      ctx.callActivity(NotifyActivity.class.getName(), notification).await();

      // Complete the workflow with order result is processed
      orderResult.setProcessed(true);
      ctx.complete(orderResult);
    };
  }

}

activities directory

The Activities directory holds the four workflow activities used by the workflow, defined in the following files:


The order-processor console app starts and manages the OrderProcessingWorkflow workflow, which simulates purchasing items from a store. The workflow consists of five unique workflow activities, or tasks:

  • NotifyActivity: Utilizes a logger to print out messages throughout the workflow. These messages notify you when:
    • You have insufficient inventory
    • Your payment couldn’t be processed, etc.
  • ProcessPaymentActivity: Processes and authorizes the payment.
  • VerifyInventoryActivity: Checks the state store to ensure there is enough inventory present for purchase.
  • UpdateInventoryActivity: Removes the requested items from the state store and updates the store with the new remaining inventory value.
  • RequestApprovalActivity: Seeks approval from the manager if payment is greater than 50,000 USD.

Step 1: Pre-requisites

For this example, you will need:

Step 2: Set up the environment

Clone the sample provided in the Quickstarts repo.

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

In a new terminal window, navigate to the order-processor directory:

cd workflows/go/sdk/order-processor

Step 3: Run the order processor app

In the terminal, start the order processor app alongside a Dapr sidecar using Multi-App Run:

dapr run -f .

This starts the order-processor app with unique workflow ID and runs the workflow activities.

Expected output:

== APP - order-processor == *** Welcome to the Dapr Workflow console app sample!
== APP - order-processor == *** Using this app, you can place orders that start workflows.
== APP - order-processor == dapr client initializing for: 127.0.0.1:50056
== APP - order-processor == adding base stock item: paperclip
== APP - order-processor == 2024/02/01 12:59:52 work item listener started
== APP - order-processor == INFO: 2024/02/01 12:59:52 starting background processor
== APP - order-processor == adding base stock item: cars
== APP - order-processor == adding base stock item: computers
== APP - order-processor == ==========Begin the purchase of item:==========
== APP - order-processor == NotifyActivity: Received order 48ee83b7-5d80-48d5-97f9-6b372f5480a5 for 10 cars - $150000
== APP - order-processor == VerifyInventoryActivity: Verifying inventory for order 48ee83b7-5d80-48d5-97f9-6b372f5480a5 of 10 cars
== APP - order-processor == VerifyInventoryActivity: There are 100 cars available for purchase
== APP - order-processor == RequestApprovalActivity: Requesting approval for payment of 150000USD for 10 cars
== APP - order-processor == NotifyActivity: Payment for order 48ee83b7-5d80-48d5-97f9-6b372f5480a5 has been approved!
== APP - order-processor == ProcessPaymentActivity: 48ee83b7-5d80-48d5-97f9-6b372f5480a5 for 10 - cars (150000USD)
== APP - order-processor == UpdateInventoryActivity: Checking Inventory for order 48ee83b7-5d80-48d5-97f9-6b372f5480a5 for 10 * cars
== APP - order-processor == UpdateInventoryActivity: There are now 90 cars left in stock
== APP - order-processor == NotifyActivity: Order 48ee83b7-5d80-48d5-97f9-6b372f5480a5 has completed!
== APP - order-processor == Workflow completed - result: COMPLETED
== APP - order-processor == Purchase of item is complete

Stop the Dapr workflow with CTRL+C or:

dapr stop -f .

(Optional) Step 4: View in Zipkin

Running dapr init launches the openzipkin/zipkin Docker container. If the container has stopped running, launch the Zipkin Docker container with the following command:

docker run -d -p 9411:9411 openzipkin/zipkin

View the workflow trace spans in the Zipkin web UI (typically at http://localhost:9411/zipkin/).

What happened?

When you ran dapr run:

  1. A unique order ID for the workflow is generated (in the above example, 48ee83b7-5d80-48d5-97f9-6b372f5480a5) and the workflow is scheduled.
  2. The NotifyActivity workflow activity sends a notification saying an order for 10 cars has been received.
  3. 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.
  4. Your workflow starts and notifies you of its status.
  5. The ProcessPaymentActivity workflow activity begins processing payment for order 48ee83b7-5d80-48d5-97f9-6b372f5480a5 and confirms if successful.
  6. The UpdateInventoryActivity workflow activity updates the inventory with the current available cars after the order has been processed.
  7. The NotifyActivity workflow activity sends a notification saying that order 48ee83b7-5d80-48d5-97f9-6b372f5480a5 has completed.
  8. The workflow terminates as completed.

order-processor/main.go

In the application’s program file:

  • The unique workflow order ID is generated
  • The workflow is scheduled
  • The workflow status is retrieved
  • The workflow and the workflow activities it invokes are registered
func main() {
	fmt.Println("*** Welcome to the Dapr Workflow console app sample!")
	fmt.Println("*** Using this app, you can place orders that start workflows.")

  // ...

  // Register workflow and activities
	if err := w.RegisterWorkflow(OrderProcessingWorkflow); err != nil {
		log.Fatal(err)
	}
	if err := w.RegisterActivity(NotifyActivity); err != nil {
		log.Fatal(err)
	}
	if err := w.RegisterActivity(RequestApprovalActivity); err != nil {
		log.Fatal(err)
	}
	if err := w.RegisterActivity(VerifyInventoryActivity); err != nil {
		log.Fatal(err)
	}
	if err := w.RegisterActivity(ProcessPaymentActivity); err != nil {
		log.Fatal(err)
	}
	if err := w.RegisterActivity(UpdateInventoryActivity); err != nil {
		log.Fatal(err)
	}

  // Build and start workflow runtime, pulling and executing tasks
	if err := w.Start(); err != nil {
		log.Fatal(err)
	}

	daprClient, err := client.NewClient()
	if err != nil {
		log.Fatalf("failed to initialise dapr client: %v", err)
	}
	wfClient, err := workflow.NewClient(workflow.WithDaprClient(daprClient))
	if err != nil {
		log.Fatalf("failed to initialise workflow client: %v", err)
	}

  // Check inventory
	inventory := []InventoryItem{
		{ItemName: "paperclip", PerItemCost: 5, Quantity: 100},
		{ItemName: "cars", PerItemCost: 15000, Quantity: 100},
		{ItemName: "computers", PerItemCost: 500, Quantity: 100},
	}
	if err := restockInventory(daprClient, inventory); err != nil {
		log.Fatalf("failed to restock: %v", err)
	}

	fmt.Println("==========Begin the purchase of item:==========")

	itemName := defaultItemName
	orderQuantity := 10

	totalCost := inventory[1].PerItemCost * orderQuantity

	orderPayload := OrderPayload{
		ItemName:  itemName,
		Quantity:  orderQuantity,
		TotalCost: totalCost,
	}

  // Start workflow events, like receiving order, verifying inventory, and processing payment 
	id, err := wfClient.ScheduleNewWorkflow(context.Background(), workflowName, workflow.WithInput(orderPayload))
	if err != nil {
		log.Fatalf("failed to start workflow: %v", err)
	}

	// ...

  // Notification that workflow has completed or failed
	for {
		timeDelta := time.Since(startTime)
		metadata, err := wfClient.FetchWorkflowMetadata(context.Background(), id)
		if err != nil {
			log.Fatalf("failed to fetch workflow: %v", err)
		}
		if (metadata.RuntimeStatus == workflow.StatusCompleted) || (metadata.RuntimeStatus == workflow.StatusFailed) || (metadata.RuntimeStatus == workflow.StatusTerminated) {
			fmt.Printf("Workflow completed - result: %v\n", metadata.RuntimeStatus.String())
			break
		}
		if timeDelta.Seconds() >= 10 {
			metadata, err := wfClient.FetchWorkflowMetadata(context.Background(), id)
			if err != nil {
				log.Fatalf("failed to fetch workflow: %v", err)
			}
			if totalCost > 50000 && !approvalSought && ((metadata.RuntimeStatus != workflow.StatusCompleted) || (metadata.RuntimeStatus != workflow.StatusFailed) || (metadata.RuntimeStatus != workflow.StatusTerminated)) {
				approvalSought = true
				promptForApproval(id)
			}
		}
		// Sleep to not DoS the dapr dev instance
		time.Sleep(time.Second)
	}

	fmt.Println("Purchase of item is complete")
}

// Request approval (RequestApprovalActivity)
func promptForApproval(id string) {
	wfClient, err := workflow.NewClient()
	if err != nil {
		log.Fatalf("failed to initialise wfClient: %v", err)
	}
	if err := wfClient.RaiseEvent(context.Background(), id, "manager_approval"); err != nil {
		log.Fatal(err)
	}
}

// Update inventory for remaining stock (UpdateInventoryActivity)
func restockInventory(daprClient client.Client, inventory []InventoryItem) error {
	for _, item := range inventory {
		itemSerialized, err := json.Marshal(item)
		if err != nil {
			return err
		}
		fmt.Printf("adding base stock item: %s\n", item.ItemName)
		if err := daprClient.SaveState(context.Background(), stateStoreName, item.ItemName, itemSerialized, nil); err != nil {
			return err
		}
	}
	return nil
}

Meanwhile, the OrderProcessingWorkflow and its activities are defined as methods in workflow.go

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