HelloCities

Hello Cities — Durable Functions PowerShell Quickstart

PowerShell | Durable Functions

Description

This quickstart demonstrates Durable Functions with PowerShell using the Durable Task Scheduler backend. It includes two patterns:

1. Function Chaining — An orchestration that calls three "say hello" activities sequentially
2. Fan-out/Fan-in — An orchestration that greets multiple cities in parallel and aggregates results

Prerequisites

1. PowerShell 7.4+
2. Azure Functions Core Tools v4
3. Docker (for the emulator)

Quick Run

1. Start the emulator:

   docker run -d -p 8080:8080 -p 8082:8082 mcr.microsoft.com/dts/dts-emulator:latest

2. Navigate to the sample directory:

   cd samples/durable-functions/powershell/HelloCities

3. Create a local.settings.json file:

   {
     "IsEncrypted": false,
     "Values": {
       "AzureWebJobsStorage": "UseDevelopmentStorage=true",
       "FUNCTIONS_WORKER_RUNTIME": "powershell",
       "DURABLE_TASK_SCHEDULER_CONNECTION_STRING": "Endpoint=http://localhost:8080;TaskHub=default;Authentication=None"
     }
   }

4. Run the function app:

   func start

5. Trigger the function chaining orchestration:

   curl -X POST http://localhost:7071/api/StartChaining

6. Trigger the fan-out/fan-in orchestration:

   curl -X POST http://localhost:7071/api/StartFanOutFanIn

7. View in the dashboard: http://localhost:8082

Expected Output

The HTTP triggers return a 202 Accepted response with status query URLs. Use the statusQueryGetUri from the response to poll for completion:

# Replace with the statusQueryGetUri value from the 202 response
curl "<statusQueryGetUri>"

Once completed, the chaining orchestration output greets Tokyo, Seattle, and London sequentially:

["Hello Tokyo!", "Hello Seattle!", "Hello London!"]

The fan-out/fan-in orchestration output greets all five cities in parallel and returns combined results:

["Hello Tokyo!", "Hello Seattle!", "Hello London!", "Hello Paris!", "Hello Berlin!"]

Using a Deployed Scheduler (Azure)

To use a Durable Task Scheduler in Azure instead of the emulator:

1. Update the connection string in local.settings.json:

   {
     "IsEncrypted": false,
     "Values": {
       "AzureWebJobsStorage": "UseDevelopmentStorage=true",
       "FUNCTIONS_WORKER_RUNTIME": "powershell",
       "DURABLE_TASK_SCHEDULER_CONNECTION_STRING": "Endpoint=<your-scheduler-endpoint>;TaskHub=<your-taskhub>;Authentication=ManagedIdentity"
     }
   }

2. Run the sample using the same commands as above.

See the Durable Task Scheduler documentation for setup instructions.

Code Walkthrough

• SayHello/ — Activity function that returns a greeting for a given city name.
• ChainingOrchestration/ — Orchestrator that calls SayHello three times in sequence.
• FanOutFanInOrchestration/ — Orchestrator that calls SayHello for five cities in parallel.
• StartChaining/ — HTTP trigger that starts the chaining orchestration.
• StartFanOutFanIn/ — HTTP trigger that starts the fan-out/fan-in orchestration.

Viewing in the Dashboard

• Emulator: Navigate to http://localhost:8082 → select the "default" task hub
• Azure: Navigate to your Scheduler resource in the Azure Portal → Task Hub → Dashboard URL

Learn More

• Durable Functions PowerShell Developer Guide
• Durable Task Scheduler Documentation