Live Data Source¶

The Live Data Source feature allows ODIN to receive and display real-time geospatial data from external systems via Server-Sent Events (SSE).

Use Cases¶

Real-time tracking: Display moving assets such as vehicles, aircraft, or personnel on the map
Sensor data visualization: Show live sensor readings with geographic positions
Situational awareness: Integrate external data feeds into your operational picture
IoT integration: Display data from IoT devices with location information

Creating a Live Data Source¶

Click the + button in the toolbar
Select Create Live Data Source
Configure the connection parameters:
Name: A descriptive name for the data source
URL: The SSE endpoint URL
Event Type: The SSE event name to listen for (default: message)
Update Interval: Rate limiting in milliseconds (default: 100ms)
Track features by ID: How to handle incoming features (see below)
Enable the checkbox to connect

Feature Tracking Modes¶

The Track features by ID option controls how incoming features are processed:

Enabled (default): Features are tracked by their id field. When a feature with the same ID arrives, it updates the existing feature (position, properties). This is ideal for tracking moving assets where each asset has a unique identifier.

Disabled: All features are replaced on each update. The previous features are cleared and new features are added. This mode is suitable for data sources that: - Don't provide feature IDs - Send complete snapshots of all features on each update - Have features that don't need individual tracking

SSE Endpoint Requirements¶

The SSE endpoint must comply with the Server-Sent Events specification.

HTTP Response Headers¶

Content-Type: text/event-stream
Cache-Control: no-cache
Connection: keep-alive

CORS¶

If the SSE endpoint is on a different origin than ODIN, it must include appropriate CORS headers:

Access-Control-Allow-Origin: *

Event Format¶

Events should be sent in the standard SSE format:

event: <event-type>
data: <json-payload>

Note: Each event must end with two newlines.

If using the default event type (message), the event: line can be omitted:

data: <json-payload>

Data Format¶

The data payload must be valid GeoJSON. Two formats are supported:

Single Feature¶

{
  "type": "Feature",
  "id": "unit-001",
  "geometry": {
    "type": "Point",
    "coordinates": [16.3738, 48.2082]
  },
  "properties": {
    "sidc": "SFGPUCI----D",
    "name": "Alpha Unit"
  }
}

Feature Collection¶

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "id": "unit-001",
      "geometry": {
        "type": "Point",
        "coordinates": [16.3738, 48.2082]
      },
      "properties": {
        "sidc": "SFGPUCI----D",
        "name": "Alpha Unit"
      }
    },
    {
      "type": "Feature",
      "id": "unit-002",
      "geometry": {
        "type": "Point",
        "coordinates": [16.3850, 48.2100]
      },
      "properties": {
        "sidc": "SFGPUCI----D",
        "name": "Bravo Unit"
      }
    }
  ]
}

Required Fields¶

Field	Description
`type`	Must be `"Feature"` or `"FeatureCollection"`
`id`	Unique identifier for the feature. Required when "Track features by ID" is enabled. Used to update existing features.
`geometry`	GeoJSON geometry object
`geometry.type`	Geometry type (e.g., `"Point"`, `"LineString"`, `"Polygon"`)
`geometry.coordinates`	Coordinates in the configured projection (default: EPSG:4326 / WGS84)

Optional Fields¶

Field	Description
`properties.sidc`	MIL-STD-2525C symbol identification code for military symbology
`properties.name`	Display name for the feature
`properties.*`	Any additional properties for styling or information

Coordinate System¶

By default, coordinates are expected in EPSG:4326 (WGS84) format: - Longitude first, then latitude: [longitude, latitude] - Example: [16.3738, 48.2082] for Vienna, Austria

The data projection can be configured in the Live Data Source settings if your endpoint uses a different coordinate system.

Example SSE Server (Node.js)¶

const http = require('http');

const server = http.createServer((req, res) => {
  if (req.url === '/api/stream') {
    res.writeHead(200, {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      'Connection': 'keep-alive',
      'Access-Control-Allow-Origin': '*'
    });

    // Send initial data
    const sendUpdate = () => {
      const data = {
        type: 'Feature',
        id: 'track-001',
        geometry: {
          type: 'Point',
          coordinates: [16.37 + Math.random() * 0.1, 48.20 + Math.random() * 0.1]
        },
        properties: {
          sidc: 'SFGPUCI----D',
          name: 'Moving Unit'
        }
      };

      res.write(`data: ${JSON.stringify(data)}\n\n`);
    };

    // Send updates every second
    const interval = setInterval(sendUpdate, 1000);
    sendUpdate();

    req.on('close', () => {
      clearInterval(interval);
    });
  } else {
    res.writeHead(404);
    res.end();
  }
});

server.listen(3000, () => {
  console.log('SSE server running on http://localhost:3000/api/stream');
});

Troubleshooting¶

Connection Issues¶

Verify the URL is correct and accessible
Check browser developer tools for CORS errors
Ensure the server sends proper SSE headers

Features Not Appearing¶

Verify the JSON payload is valid
If "Track features by ID" is enabled, check that the id field is present on each feature
If your data source doesn't provide IDs, disable "Track features by ID"
Ensure coordinates are in the correct order (longitude, latitude)
Verify the event type matches the configured value

Features Not Updating¶

Ensure "Track features by ID" is enabled
Ensure each update uses the same id for features that should be updated
Check the update interval setting - very low values may cause performance issues