When a DCM device starts up, it needs to know which product slots it has, what their properties are, and any device-type-specific configuration values. This information is delivered to the device over MQTT - firmware does not call any HTTP endpoint directly.
The extensible fields system lets you attach typed custom attributes to any platform entity — without writing code or changing the schema. Tenant administrators define the fields they need, assign them to specific entity types, and start recording values immediately.
This guide walks through creating categories, defining attributes, assigning them to entity types, recording values, and querying extensible field data. It uses a DCM (Device Control Management) vending machine as the example entity.