This sample demonstrates how to compose workflows hierarchically by using sub-workflows within a durable orchestration. Sub-workflows are executed as separate orchestration instances, providing modularity, reusability, and excellent visibility in the Durable Task dashboard.

Overview

The sample implements an order processing system with three sub-workflows:

OrderProcessing (Main Workflow)
??? OrderReceived
??? Payment (Sub-Workflow)
?   ??? ValidatePayment (1s)
?   ??? ChargePayment (2s)
??? Inventory (Sub-Workflow)
?   ??? CheckInventory (1s)
?   ??? ReserveInventory (2s)
??? Shipping (Sub-Workflow)
?   ??? SelectCarrier (1s)
?   ??? CreateShipment (2s)
??? OrderCompleted

Key Concepts

Sub-Workflow Benefits

Modularity: Each sub-workflow encapsulates related logic (payment, inventory, shipping)
Reusability: Sub-workflows can be used in multiple parent workflows
Independent Execution: Each sub-workflow runs as a separate orchestration instance
Dashboard Visibility: Sub-workflows appear in the Timeline view with parent-child relationships
Failure Isolation: A failure in a sub-workflow doesn't corrupt the parent's state

How Sub-Workflows Work

// Step 1: Build a sub-workflow
Workflow paymentWorkflow = new WorkflowBuilder(validatePayment)
    .WithName("PaymentProcessing")
    .AddEdge(validatePayment, chargePayment)
    .Build();

// Step 2: Bind it as an executor for use in a parent workflow
ExecutorBinding paymentExecutor = paymentWorkflow.BindAsExecutor("Payment");

// Step 3: Use the sub-workflow executor in the main workflow
Workflow mainWorkflow = new WorkflowBuilder(orderReceived)
    .AddEdge(orderReceived, paymentExecutor)  // Sub-workflow as an edge target
    .AddEdge(paymentExecutor, inventoryExecutor)
    .Build();

// Step 4: Register only the main workflow - sub-workflows are discovered automatically!
services.ConfigureDurableWorkflows(
    options => options.Workflows.AddWorkflow(mainWorkflow),
    ...);

Dashboard Visualization

Open the DTS dashboard at http://localhost:8080 after running a workflow:

Click on the main orchestration instance
Switch to the Timeline tab
You'll see a hierarchical view showing:
- OrderProcessing (parent orchestration)
- PaymentProcessing (sub-orchestration)
- InventoryManagement (sub-orchestration)
- ShippingArrangement (sub-orchestration)

Each sub-orchestration has its own instance ID and can be inspected independently.

Environment Setup

See the README.md file in the parent directory for information on:

Installing prerequisites (.NET 10+, Docker)
Starting the Durable Task Scheduler emulator
Configuring environment variables

Running the Sample

# Start the DTS emulator (if not already running)
docker run -d --name dts-emulator -p 8080:8080 -p 8082:8082 mcr.microsoft.com/dts/dts-emulator:latest

# Run the sample
cd dotnet/samples/DurableAgents/ConsoleApps/09_SubWorkflows
dotnet run --framework net10.0

Sample Session

????????????????????????????????????????????????????????????????????
?           Durable Sub-Workflows Sample                           ?
????????????????????????????????????????????????????????????????????
?  Main Workflow: OrderProcessing                                  ?
?  ??? Payment (sub-workflow)                                      ?
?  ?   ??? ValidatePayment (1s)                                    ?
?  ?   ??? ChargePayment (2s)                                      ?
?  ??? Inventory (sub-workflow)                                    ?
?  ?   ??? CheckInventory (1s)                                     ?
?  ?   ??? ReserveInventory (2s)                                   ?
?  ??? Shipping (sub-workflow)                                     ?
?      ??? SelectCarrier (1s)                                      ?
?      ??? CreateShipment (2s)                                     ?
????????????????????????????????????????????????????????????????????

Open the DTS dashboard at http://localhost:8080 to see the
parent-child orchestration hierarchy in the Timeline view!

Enter an order ID (or 'exit'):
> ORD-12345

Starting order processing for 'ORD-12345'...
Instance ID: abc123def456
Check the DTS dashboard Timeline tab to see sub-orchestrations!

[OrderReceived] Processing order 'ORD-12345'
  [Payment/ValidatePayment] Validating payment for order 'ORD-12345'...
  [Payment/ValidatePayment] Payment validated for $99.99
  [Payment/ChargePayment] Charging $99.99 for order 'ORD-12345'...
  [Payment/ChargePayment] ? Payment processed: TXN-A1B2C3D4
  [Inventory/CheckInventory] Checking inventory for order 'ORD-12345'...
  [Inventory/CheckInventory] ? Items available in stock
  [Inventory/ReserveInventory] Reserving items for order 'ORD-12345'...
  [Inventory/ReserveInventory] ? Reserved: RES-E5F6G7H8
  [Shipping/SelectCarrier] Selecting carrier for order 'ORD-12345'...
  [Shipping/SelectCarrier] ? Selected carrier: Express
  [Shipping/CreateShipment] Creating shipment for order 'ORD-12345'...
  [Shipping/CreateShipment] ? Shipment created: TRACK-I9J0K1L2M3
???????????????????????????????????????????????????????????????????
? [OrderCompleted] Order 'ORD-12345' successfully processed!
?   Payment: TXN-A1B2C3D4
?   Inventory: RES-E5F6G7H8
?   Shipping: Express - TRACK-I9J0K1L2M3
???????????????????????????????????????????????????????????????????
? Order completed. Tracking: TRACK-I9J0K1L2M3

Comparison with In-Process Sub-Workflows

Feature	In-Process	Durable
Execution	Same process, synchronized supersteps	Separate orchestration instances
Visibility	Single workflow view	Hierarchical dashboard view
Checkpointing	Parent checkpoints include child state	Independent checkpoints per sub-workflow
Failure Recovery	Parent must handle child failures	Automatic retry with state preservation
Scalability	Single process	Can scale across workers

06_SubWorkflows (In-Process) - In-process sub-workflow execution
08_SingleWorkflow - Basic durable workflow without sub-workflows

README.md

Sub-Workflows Console Sample