Azure Maps and GeoFence

This is a continuation of a series of articles on operational engineering aspects of Azure public cloud computing. In this article, we continue on the discussion on Azure Maps which is a full-fledged general availability service that provides similar Service Level Agreements as expected from others in the category.

Azure Maps is a collection of geospatial services and SDKs that fetches the latest geographic data and provides it as a context to web and mobile applications.  Specifically, it provides REST APIs to render vector and raster maps as overlays including satellite imagery, provides creator services to enable indoor map data publication, provides search services to locate addresses, places, and points of interest given indoor and outdoor data, provides various routing options such as point-to-point, multipoint, multipoint optimization, isochrone, electric vehicle, commercial vehicle, traffic influenced, and matrix routing, provides traffic flow view and incidents view, for applications that require real-time traffic information, provides Time zone and Geolocation services, provides elevation services with Digital Elevation Model, provides Geofencing service and mapping data storage, with location information hosted in Azure and provides Location intelligence through geospatial analytics.

Azure Maps can be helpful for tracking entry and exit into a geographical location such as the perimeters of a construction area. Such tracking can be used to generate notifications by email. A Geofencing GeoJSON data is uploaded to define the construction area we want to monitor.  The Data Upload API will be used to upload geofences as polygon coordinates to the Azure Maps Account. Two logic apps can be written to send email notifications to the construction site operations when say a equipment enters or exit the construction site. An Azure Event Grid will subscribe to enter and exit events for Azure Maps geofence. Two webhook event subscriptions will call the HTTP endpoints defined in the two logic applications. The Search GeoFence Get API is used to receive notifications when a piece of equipment enters or exits the geofence areas.

The Geofencing GeoJSON data contains a FeatureCollection which consists of two geofences that pertain to distinct polygonal areas within the construction site. The first has no time expirations or restrictions and the second can only be queried during business hours. This data can be uploaded with a POST method call to the mapData endpoint along with the subscription key. Once the data is uploaded,  we can retrieve its metadata to ascertain the created timestamp.

The Logic App will require a resource group and subscription to be deployed. A common trigger function to respond when an HTTP request is received, is sufficient for this purpose. Then the Azure Maps event subscriptions is created. It will require name, event schema, system topic name, filter to event types, endpoint type and endpoint. The Spatial Geofence Get API will send out the notifications on the entry to and exit from the geofence. Each equipment has a device id which is unique so both the entry and exit can be noted. The get method also returns a location in the form of x,y distance from the geofence. A negative distance will imply that the data will lie directly within the polygon.