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Roaming Geofences

Roaming Geofence animation

Tile38 1.2 introduces a powerful new feature which allows for dynamic geofences. This enables realtime monitoring for when one or more moving objects are nearby each other.

A couple of common use cases are:

  • Vehicle pickup services: Instantly be notified when a vehicle is nearby somebody waiting to be picked up, or when a person approaches a vehicle, or when a vehicle is nearby other vehicles in the fleet.

  • Proximity social apps: Very useful for when you need to check if two users are nearby each other without having to constantly query the database.


A simple example:

NEARBY people FENCE ROAM people * 5000

This will open a roaming fence on the people collection. The fence watches for when any object is within 5000 meters of any other object in the same collection.

To test, open two terminals:

Terminal 1

Connect to the Tile38 server and enter the fence command.

$ tile38-cli
localhost:9851> NEARBY people FENCE ROAM people * 5000
+OK

Terminal 2

Add two points to the people collection. The second SET command will trigger a fence event that will appear in the other terminal.

$ tile38-cli
localhost:9851> SET people bob POINT 33.01 -115.01
localhost:9851> SET people alice POINT 33.02 -115.02

The event will appear in terminal 1 and look like:

{
  "command": "set",
  "detect": "roam",
  "hook": "",
  "key": "people",
  "id": "alice",
  "time": "2016-05-24T09:19:44.08649461-07:00",
  "object": { "type": "Point", "coordinates": [-115.02, 33.02] },
  "nearby": {
    "key": "people",
    "id": "bob",
    "meters": 1451.138152186708
  }
}

Which shows that alice was updated and that bob is 1,451 meters away.

Some other examples:

# Watch `alice` and `bob` for when they are within 100 meters of each other.
NEARBY people MATCH alice FENCE ROAM people bob 100
# Watch objects beginning in 'a' for when they within 100 meters of any object in the friends collection.
NEARBY people MATCH a* FENCE ROAM friends * 100

And if you are using webhooks you can assign this fence like such:

SETHOOK myhook http://10.0.1.5/hook NEARBY people FENCE ROAM people * 5000

NODWELL Keyword

One side effect is that you may get a lot of nearby notifications when two objects continue to be nearby each other. If this is a problem then use the NODWELL keyword.

tile38-cli> NEARBY people FENCE NODWELL ROAM people * 5000

This will ensure that there is repeating nearby or faraway notifications for two connecting objects.

← Geofencing