SystemTelemetryReporter

A Windows .NET console application that collects Windows Performance Counter telemetry from the local machine and reports it to Azure IoT Hub on a configurable interval. On startup the application auto-registers the device with IoT Hub using the machine hostname as the Device ID and begins streaming JSON telemetry.

This project was created as part of an asset digital twin test using Azure Digital Twins (ADT). Telemetry data is sent to Azure IoT Hub, routed to Blob Storage, and then consumed by ADT.

Requirements

Requirement	Version
.NET SDK	8.0
Target Framework	net8.0-windows
OS	Windows (Performance Counter API requirement)
Azure IoT Hub	Any tier (Free, S1, S2, S3)

NuGet Dependencies

Package	Version
Microsoft.Azure.Devices	1.41.0
Microsoft.Azure.Devices.Client	1.42.3
System.Diagnostics.PerformanceCounter	7.0.0

Configuration

The application requires two environment variables.

Both variables must be set before running the application.

Replace the placeholder values with your Azure IoT Hub configuration.

Variable	Description	Value to Set
IOT_HUB_CONNECTION_STRING	IoT Hub service-level connection string (Registry Read/Write permission)	HostName=YOUR_IOT_HUB_SERVICE_HOSTNAME;SharedAccessKeyName=YOUR_KEY_NAME;SharedAccessKey=YOUR_SERVICE_KEY
HOST_NAME	IoT Hub hostname used when constructing the device connection string	YOUR_IOT_HUB_HOSTNAME

Example (Replace placeholders with actual values)

$env:IOT_HUB_CONNECTION_STRING = "HostName=your-iot-hub.azure-devices.net;SharedAccessKeyName=iothubowner;SharedAccessKey=your_service_key_here"
$env:HOST_NAME = "your-host-name.azure-devices.net"

Or set them permanently via System Properties > Environment Variables.

Build, Clean & Run

From the repository root, run the following dotnet CLI commands.

Restore dependencies

dotnet restore

Clean

dotnet clean

Build

dotnet build

Run

dotnet run

How It Works

1. Device registration - On startup, the machine hostname (Environment.MachineName) is used as the Device ID. The application connects to IoT Hub via RegistryManager and registers the device. If the device already exists, it retrieves the existing record.
2. Device client - A DeviceClient is created from the device connection string.
3. Telemetry loop - Windows Performance Counters are initialised and read every 30 minutes. The values are serialised to a JSON object and sent to IoT Hub as a device-to-cloud message.

Console Output

Creating device identity...
Device ID: <HOSTNAME>
Adding device identity to IoT Hub...
Device identity already exists. Retrieving device...
Device identity created successfully.
Device client created successfully.
Reporting telemetry every 30 minutes...
Telemetry sent: { ... }

Telemetry Payload Structure

Each message is a flat JSON object. Keys follow the pattern <Category>_<Counter>. All values are double.

{
  "Memory_Committed Bytes":          0.0,
  "Memory_Available Bytes":          0.0,
  "Memory_Available MBytes":         0.0,
  "Memory_% Committed Bytes In Use": 0.0,
  "Memory_Cache Bytes":              0.0,
  "Memory_Pool Paged Bytes":         0.0,
  "Memory_Pool Nonpaged Bytes":      0.0,
  "Memory_Pages/sec":                0.0,
  "Memory_Page Faults/sec":          0.0,

  "System_Processes":                0.0,
  "System_System Up Time":           0.0,
  "System_Context Switches/sec":     0.0,
  "System_Processor Queue Length":   0.0,

  "Process_Thread Count":            0.0,
  "Process_Handle Count":            0.0,

  "LogicalDisk_% Disk Time":                  0.0,
  "LogicalDisk_% Disk Read Time":             0.0,
  "LogicalDisk_% Disk Write Time":            0.0,
  "LogicalDisk_% Idle Time":                  0.0,
  "LogicalDisk_Disk Bytes/sec":               0.0,
  "LogicalDisk_Disk Write Bytes/sec":         0.0,
  "LogicalDisk_Disk Transfers/sec":           0.0,
  "LogicalDisk_Disk Reads/sec":               0.0,
  "LogicalDisk_Disk Writes/sec":              0.0,
  "LogicalDisk_Avg. Disk sec/Transfer":       0.0,
  "LogicalDisk_Avg. Disk sec/Read":           0.0,
  "LogicalDisk_Avg. Disk sec/Write":          0.0,
  "LogicalDisk_Avg. Disk Queue Length":       0.0,
  "LogicalDisk_Avg. Disk Read Queue Length":  0.0,
  "LogicalDisk_Avg. Disk Write Queue Length": 0.0,
  "LogicalDisk_% Free Space":                 0.0,
  "LogicalDisk_Free Megabytes":               0.0
}

Project Structure

SystemTelemetryReporter/
├── Program.cs                             # Entry point; device setup and telemetry loop
├── SystemTelemetryReporter.csproj
├── SystemTelemetryReporter.sln
├── Identity/
│   └── DeviceIdentityService.cs           # Registers / retrieves the device in IoT Hub
└── Telemetry/
    ├── TelemetryService.cs                # Initialises and reads Performance Counters
    └── Constants/
        └── PerformanceCounters/
            ├── Categories.cs              # Performance Counter category name constants
            ├── Counter.cs                 # PerformanceCounterDefinition model
            └── Counters.cs                # Counter name constants per category