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Device Configuration Application Behavior

Sharon Dhesi

Device Configuration Application Behavior

Summary

This article explains how configuration changes are delivered and applied on LightMetrics devices, how applyImmediately affects trip behavior, and what operational impact Support should expect. The design ensures that each trip runs with a consistent configuration set.

Core Behavior

Trip-Based Configuration Consistency

From APK version 1.23.0 onward, configuration changes are downloaded during an active trip but are not applied until the device completes a safe lifecycle transition (boot or suspend). This prevents mid-trip configuration drift and ensures consistent trip data.

Configuration Delivery

  • Primary: Push notification (near real-time delivery)
  • Fallback: Polling every 24 hours (guaranteed delivery window)

Default Application Flow

Standard Mode (applyImmediately = false)

The device downloads and stores the latest configuration locally but continues the current trip using the existing configuration. The update is applied only after the trip ends and the device enters suspend or completes a power cycle.

The diagram illustrates this behavior: the configuration is changed in the backend during an active trip, fetched by the device, but not applied. After the trip ends and the device transitions through suspend, the next trip starts with the updated configuration.

Lifecycle Behavior

  • Suspend enabled → Config applies after suspend → next trip
  • Suspend disabled → Config applies on next boot

Immediate Application Flow

Immediate Mode (applyImmediately = true)

The current trip is terminated immediately and a new trip begins with the updated configuration.

[!warning] Immediate Apply Impact Enabling applyImmediately = true restarts the trip instantly, resets trip-level identifiers, and may result in driverId becoming UNASSIGNED depending on driver persistence configuration. GPIO-triggered behaviors may also occur due to trip restart.

Sample JSON Body for API Users

Full Example

{
  "configuration": {
    "light": {},
    "medium": {},
    "heavy": {},
    "default": {}
  },
  "applyImmediately": true
}

Minimal Example

{
  "configuration": {},
  "applyImmediately": true
}

Behavior Summary

  • true → Ends current trip, applies config immediately
  • false → Applies config on next trip

Limitations

Platform

  • Fleet / Master Portal → Does not support immediate apply

API

  • Package Change API → Does not support applyImmediately

Version Notes

Version 1.24

MDVR configuration changes trigger trip restart instead of app restart

Version 1.24.5

MDVR-related actions (package add/toggle) trigger trip restart instead of app restart

Decision Guidance

Use Immediate Apply When

  • Immediate enforcement is required
  • Trip interruption is acceptable

Use Default Mode When

  • Trip continuity is required
  • No disruption to field operations is desired

Operational Notes

  • Configurations are always downloaded before application
  • Max delay for delivery is 24 hours
  • Each trip runs with a single configuration snapshot

Attribution

LightMetrics https://lightmetrics.freshdesk.com/support/solutions/articles/61000317212