@Moi_Nccncc -- To expand on what @Amir-Sarrafzadeh-Arasi suggests, yes, you want to use geofences to capture the buffered areas around the point locations of the trucks from your AVL. You need to do this in two steps:
- Use a Buffer Creator processor to construct an elliptical buffer around the last-known / latest-reported position of a truck. Allow the processor to replace the truck's point location (geometry) with the computed polygon. Then push the event record with its polygon geometry out as a feature record so that a Geofence Synchronization Rule can use the feature record to add / update a geofence in the GeoEvent Server's registry of known areas.
- In a second GeoEvent Service, use a GeoTagger processor to identify which geofences (elliptical areas) a given Truck's point location intersects. The name of each polygon geofence should be the TRACK_ID (e.g. vehicle name or identifier) of the truck whose location was used to create the buffered area.
Now, you have a few things to consider. First is the rate at which AVL data is coming into your GeoEvent Server. Using a feature service to store feature records which are queried to update geofences will introduce significant latency in getting the geofences updated. The alternative is to use a stream service to broadcast the feature records with their elliptical geometries. A Geofence Synchronization Rule can be configured to subscribe to a stream service so the data is "pushed" into the geofence registry rather than requiring the synchronization rule to "poll" or query the feature records from a geodatabase.
You also have to recognize the fundamental race condition (when receiving an updated AVL point location) between using that point location to both update a polygon geofence and processor the point location to determine if it intersects any other geofences you've created / updated from other truck point locations. You have to accept that the last-known / latest-reported position of a truck can only be compared to established geofences and allow some time for the geofence synchronization to make those updates to the geofence registry before trying to determine if the "latest" point location intersects a geofence.
How you choose to output the polygon buffer feature records matters. It will take some time to create an elliptical buffer, write the constructed geometry out as a feature record to a feature service, and a synchronization rule to then retrieve that feature record and update the GeoEvent Server's geofence registry.
If you use a feature service for your synchronization you must not set the synchronization rule's Refresh Interval too aggressively. You cannot, for example, expect GeoEvent Server's Geofence Synchronization Rule to query a feature service every second and update the geofence registry -- not when are also expecting to create and update those polygon feature records and ingest, adapt and process the AVL location data records to determine intersections with the geofences. The default for geofence synchronization using a feature service is to query the feature service once every 15 minutes. You might set the Refresh Interval to run as quickly as once a minute, but I would not set it to run any more frequently than that. I would probably use a stream service to drive the geofence synchronization to minimize the latency in updating the geofence registry.
A final consideration is that a vehicle's point location will most likely intersect that same vehicle's buffered location (e.g. geofence). The first GeoEvent Service is creating the polygon buffers and driving updates into the geofence registry. The second GeoEvent Service is receiving the same point locations and using the established geofences to determine intersections. You will probably want to use something like a Field Splitter processor to split the comma delimited list of geofence(s) names produced by your GeoTagger and then Filter to discard any event record where the geofence name matches the truck's TRACK_ID. You only want to keep event records where a truck's point location intersects some other truck's buffered location.
