Geflagd

Geflagd is a geospatial event daemon designed to monitor a stream of location data against a set of geofence definitions and emit flags when geofence rules are triggered. It is intended for use in systems that need automated, real-time awareness of asset movements, such as logistics, drone operations, or location-based services.

Key features include support for polygonal and circular geofences, real-time processing, the ability to manage multiple geofences concurrently, and pluggable outputs such as HTTP callbacks, message queues, or log sinks. Geofence definitions are typically provided in GeoJSON, while input location streams may arrive as JSON payloads or through a streaming API. The daemon emphasizes low-latency processing and predictable event timing.

Architecturally, geflagd comprises a geofence store, a position processor, an event notifier, and adapters for data inputs and outputs. It relies on a spatial index and geospatial libraries to accelerate containment tests, and it can run as a background service on Unix-like systems or Windows. It exposes a lightweight API for querying current flags and for subscribing to events.

Configuration is performed via a config file that defines geofences, data sources, and notification endpoints. On startup, geflagd loads the geofence set and begins processing incoming locations, emitting enter, exit, or intersection events tagged with timestamps and identifiers. Limitations include a focus on real-time event generation rather than long-term history, unless augmented with external storage.

See also geofencing, GIS, GeoJSON, geospatial analysis.