Metrici LPR Plugin for Milestone XProtect

1. Features

• HTTP API Endpoint: Receives LPR data (multipart/form‑data).
• Authentication: MD5‑based per‑camera authentication.
• Event Storage: SQLite database for persistent event storage.
• Rich UI – main view, side panel, detailed event viewer.
• Real‑time Updates and automatic refresh.
• Export Functionality to text files.
• Administration Interface for camera configuration.

2. System Requirements

• Milestone XProtect (compatible with MIPSDK)
• .NET Framework 4.7.2 or later
• Windows Server 2016+ (for server components) or Windows 10/11 (client)
• Open TCP port 8080 (or custom) for HTTP communication

3. Installation

1. Build the plugin (if building from source):

   dotnet restore MetriciLprPlugin.sln
   dotnet build MetriciLprPlugin.sln --configuration Release

2. Deploy the assemblies to the XProtect plugins folder, e.g.

   C:\Program Files\Milestone\XProtect <Version>\Server\Plugins\MetriciLprPlugin\
     MetriciLprPlugin.dll
     MetriciLprPlugin.Admin.dll

3. Register the plugin in the XProtect Management Application → Servers → Plugins → Add → select MetriciLprPlugin.dll and enable it.
4. Configure basic settings (HTTP port, authentication key, data directory) through the plugin configuration UI.
5. Open firewall for the chosen port, e.g.:

   New-NetFirewallRule -DisplayName "Metrici LPR Plugin" -Direction Inbound -Protocol TCP -LocalPort 8080 -Action Allow

6. Restart XProtect services (Smart Client, Management Server, Recording Server, Event Server) and verify the plugin loads.

4. Configuration

Camera Configuration

Through the XProtect Management Client → Plugin Configuration → Camera Configuration you can add each LPR camera:

• Camera ID (matching the Metrici engine)
• Unique authentication key (MD5 secret)
• Mapping to an XProtect camera
• Location, description, enable/disable flag

HTTP Server Settings

• Port – default 8080 (configurable)
• Endpoint – POST /lpr/event
• Health check – GET /lpr/health

Per‑Camera Authentication

Each request must contain an auth field – an MD5 hash calculated from the request fields plus the camera‑specific secret key.

5. API Usage

Required fields (multipart/form‑data)

• id – Camera ID (integer)
• number – License plate string
• country_code
• first_seen – yyyy‑mm‑dd_hh:mm:ss
• last_seen
• probability – confidence (0‑1)
• direction – 1=incoming, 2=outgoing, 3=unknown
• transactionkey
• auth – MD5 hash

Optional fields

• plate_image, car_image, companion_image (base64 JPEG)
• GPS coordinates, vehicle attributes, etc.

Example request

curl -X POST http://localhost:8080/lpr/event \
  -F "id=1" \
  -F "number=ABC123" \
  -F "country_code=RO" \
  -F "first_seen=2024-01-15_14:30:25" \
  -F "last_seen=2024-01-15_14:30:27" \
  -F "probability=0.95" \
  -F "direction=1" \
  -F "transactionkey=tx_12345" \
  -F "vehicle_class=Car" \
  -F "auth=YOUR_MD5_HASH" \
  -F "plate_image=@plate.jpg" \
  -F "car_image=@car.jpg"

6. User Interface

Main View

• Event grid with sorting, filtering (plate, vehicle type, direction, XProtect camera, date range).
• Auto‑refresh and manual refresh options.
• Double‑click an event to open detailed view with images and camera mapping.

Side Panel

• Shows the last 10 events with colour‑coded direction.
• Statistics – total events, today's count.
• Quick double‑click to open event details.

Administration Interface

• Camera configuration – add/edit/delete LPR cameras, map to XProtect cameras, set authentication keys.
• General settings – HTTP port, fallback authentication key, data directory, logging level.

7. Development

The project is a WinForms‑based .NET solution. Key components include:

• LprEventService – database operations.
• LprHttpServer – Kestrel HTTP server.
• AuthenticationService – MD5 validation.
• UI components under src/MetriciLprPlugin/UI.

To build from source:

# Restore packages
dotnet restore

# Build Release
dotnet build --configuration Release

# Run tests (if any)
dotnet test

8. Troubleshooting

Common Issues

• HTTP server won't start – check port usage, firewall, permissions.
• Authentication failures – verify per‑camera key and MD5 hash calculation.
• Database errors – ensure write permissions to the data directory.
• Plugin not loading in XProtect – confirm .NET version, file permissions, and that the DLLs are placed in the correct plugins folder.

9. Support

For technical support, consult the plugin logs (located in the application data directory) or contact the development team. More information about Metrici solutions is available at www.metrici.ro.