go-sdk workflow quickstart

workflows/go/sdk/README.md

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+# Dapr workflows
+
+In this quickstart, you'll create a simple console application to demonstrate Dapr's workflow programming model and the workflow authoring client. The console app 
+starts and manages an order processing workflow.
+The workflow management API provided by the Dapr client can also be used interchangeably with minor adjustments
+
+This quickstart includes one project:
+
+- Go app `order-processor` 
+
+The quickstart contains 1 workflow (OrderProcessingWorkflow) which simulates purchasing items from a store, and 5 unique activities within the workflow. These 5 
+activities are as follows:
+
+- NotifyActivity: This activity utilizes a logger to print out messages throughout the workflow. These messages notify the user when there is insufficient 
+§inventory, their payment couldn't be processed, and more.
+- ProcessPaymentActivity: This activity is responsible for processing and authorizing the payment.
+- VerifyInventoryActivity: This activity checks the state store to ensure that there is enough inventory present for purchase.
+- UpdateInventoryActivity: This activity removes the requested items from the state store and updates the store with the new remaining inventory value.
+- RequestApprovalActivity: This activity seeks approval from Manager, if payment is greater than 50000 USD.
+
+### Run the order processor workflow
+
+1. Open a new terminal window and navigate to `order-processor` directory.
+2. Run the console app with Dapr: 
+<!-- STEP
+name: Running this example
+expected_stdout_lines:
+  - "for 10 cars - $150000"
+  - "There are 100 cars available for purchase"
+  - "Requesting approval for payment of 150000USD for 10 cars"
+  - "has been approved!"
+  - "There are now 90 cars left in stock"
+  - "Workflow completed - result: COMPLETED"
+output_match_mode: substring
+background: true
+timeout_seconds: 120
+sleep: 30
+-->
+
+```sh
+
+dapr run -f .
+```
+
+3. 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
+```
+
+4. Stop Dapr workflow with CTRL-C or:
+<!-- END_STEP -->
+
+```sh
+dapr stop -f .
+```
+
+
+
+### View workflow output with Zipkin
+
+For a more detailed view of the workflow activities (duration, progress etc.), try using Zipkin.
+
+1. View Traces in Zipkin UI - In your browser go to http://localhost:9411 to view the workflow trace spans in the Zipkin web UI. The order-processor workflow 
+should be viewable with the following output in the Zipkin web UI. Note: the [openzipkin/zipkin](https://hub.docker.com/r/openzipkin/zipkin/) docker container is 
+launched on running `dapr init`.
+
+<img src="img/workflow-trace-spans-zipkin.png">
+
+### What happened? 
+
+When you ran the above comands:
+
+1. First the "user" inputs an order for 10 cars into the concole app.
+2. A unique order ID for the workflow is generated (in the above example, `b903d749cd814e099f06ebf4a56a2f90`) and the workflow is scheduled.
+3. The `NotifyActivity` workflow activity sends a notification saying an order for 10 cars has been received.
+4. The `VerifyInventoryActivity` workflow activity checks the inventory data, determines if you can supply the ordered item, and responds with the number of cars 
+in stock.
+5. The `RequestApprovalActivity` workflow activity is triggered due to buisness logic for orders exceeding $50k and user is prompted to manually approve the 
+purchase before continuing the order. 
+6. The workflow starts and notifies you of its status.
+7. The `ProcessPaymentActivity` workflow activity begins processing payment for order `b903d749cd814e099f06ebf4a56a2f90` and confirms if successful.
+8. The `UpdateInventoryActivity` workflow activity updates the inventory with the current available cars after the order has been processed.
+9. The `NotifyActivity` workflow activity sends a notification saying that order `b903d749cd814e099f06ebf4a56a2f90` has completed.
+10. The workflow terminates as completed.
+
+
+
+
+
+

workflows/go/sdk/dapr.yaml

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+version: 1
+common:
+  resourcesPath: ../../components
+apps:
+  - appDirPath: ./order-processor/
+    appID: order-processor
+    command: ["go", "run", "."]
+

workflows/go/sdk/makefile

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+include ../../../docker.mk
+include ../../../validate.mk

workflows/go/sdk/order-processor/main.go

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+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"time"
+
+	"github.com/dapr/go-sdk/client"
+	"github.com/dapr/go-sdk/workflow"
+)
+
+var (
+	stateStoreName    = "statestore"
+	workflowComponent = "dapr"
+	workflowName      = "OrderProcessingWorkflow"
+	defaultItemName   = "cars"
+)
+
+func main() {
+	fmt.Println("*** Welcome to the Dapr Workflow console app sample!")
+	fmt.Println("*** Using this app, you can place orders that start workflows.")
+
+	w, err := workflow.NewWorker()
+	if err != nil {
+		log.Fatalf("failed to start worker: %v", err)
+	}
+
+	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)
+	}
+
+	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)
+	}
+
+	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,
+	}
+
+	id, err := wfClient.ScheduleNewWorkflow(context.Background(), workflowName, workflow.WithInput(orderPayload))
+	if err != nil {
+		log.Fatalf("failed to start workflow: %v", err)
+	}
+
+	approvalSought := false
+
+	startTime := time.Now()
+
+	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")
+}
+
+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)
+	}
+}
+
+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
+}

workflows/go/sdk/order-processor/models.go

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+package main
+
+type OrderPayload struct {
+	ItemName  string `json:"item_name"`
+	TotalCost int    `json:"total_cost"`
+	Quantity  int    `json:"quanity"`
+}
+
+type OrderResult struct {
+	Processed bool `json:"processed"`
+}
+
+type InventoryItem struct {
+	ItemName    string `json:"item_name"`
+	PerItemCost int    `json:"per_item_cost"`
+	Quantity    int    `json:"quanity"`
+}
+
+type InventoryRequest struct {
+	RequestID string `json:"request_id"`
+	ItemName  string `json:"item_name"`
+	Quantity  int    `json:"quanity"`
+}
+
+type InventoryResult struct {
+	Success       bool          `json:"success"`
+	InventoryItem InventoryItem `json:"inventory_item"`
+}
+
+type PaymentRequest struct {
+	RequestID          string `json:"request_id"`
+	ItemBeingPurchased string `json:"item_being_purchased"`
+	Amount             int    `json:"amount"`
+	Quantity           int    `json:"quantity"`
+}
+
+type ApprovalRequired struct {
+	Approval bool `json:"approval"`
+}
+
+type Notification struct {
+	Message string `json:"message"`
+}