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The architecture of TomTom SDKs is modular, meaning that each navigation component is independent of the others.

As a result of this modularization, components are easily replaced with ones from other sources or omitted when they are not needed. Modularity makes it easier to change the standard SDK to address a specific use case.

These replaceable components are referred to as engines.

Orchestrator

The Navigation module depends on engines to orchestrate a pipeline after each location update. The location updates are supplied by the LocationProvider. Read more about the LocationProvider used by the navigation in the Location tracking guide. Different engines are used during different parts of the navigation flow, as shown in the following figure.

The orchestrator contains two main checks that determine if the calculation should continue, or stop for a given location update. After matching a location to the map and providing location context, the pipeline stops if navigation:

• is in free driving mode (i.e., there is no route).
• has detected a deviation from the route.

If none of the conditions is met, the flow proceeds with calculating route progress. A deviation event stops the rest of the pipeline from executing and switches navigation to free driving mode.

Engines

The orchestrator works with the following engines:

• MapMatchingEngine - This improves the accuracy of a position by attempting to match it to a map or a route.
• RouteReplanningEngine - This replans routes.
• GuidanceEngine - This generates guidance for upcoming road maneuvers.
• RouteTrackingEngine - This detects whether the driver follows or deviates from the route.
• RouteProgressEngine - This determines the progress made so far along the current route.
• ArrivalDetectionEngine - This checks whether the route destination is reached.

Customized engines are specified in two ways:

• During creation of the Configuration object.
• Dynamically on an existing TomTomNavigation object using NavigationEngineRegistry.
  CopytomTomNavigation.navigationEngineRegistry.updateEngines( mapMatchingEngine = mapMatchingEngine, guidanceEngine = guidanceEngine, routeProgressEngine = routeProgressEngine, routeTrackingEngine = routeTrackingEngine, arrivalDetectionEngine = arrivalDetectionEngine )

  1tomTomNavigation.navigationEngineRegistry.updateEngines(
  2    mapMatchingEngine = mapMatchingEngine,
  3    guidanceEngine = guidanceEngine,
  4    routeProgressEngine = routeProgressEngine,
  5    routeTrackingEngine = routeTrackingEngine,
  6    arrivalDetectionEngine = arrivalDetectionEngine
  7)

Navigation snapshot

Navigation session data is passed between different engines and pipeline iterations using NavigationSnapshot.

The snapshot doesn’t contain all session data, just what other engines need as input (e.g., the RouteProgressEngine uses the MapMatchingResult to calculate the progress along the route). You can see the order that engines use data in the description of the orchestrator.

Because it provides other engines with input data, the navigation snapshot always contains current information about the navigation session, such as current location, matched location, and progress along a route. It is updated whenever new values are available.

The data is divided into the following classes:

• LocationSnapshot - contains information specific to location e.g., the MapMatchingResult.
• ConfigurationSnapshot - the navigation configuration, e.g., the UnitSystem used for guidance.
• Vehicle - the current vehicle profile.
• TripSnapshot - information about the current trip session, e.g., if the driver has deviated from the route or reached the destination.
• RouteSnapshot - route-specific data such as the RoutePlan, RouteProgress, or visited waypoints.

The current navigation snapshot can be accessed using the TomTomNavigation.navigationSnapshot property. Note that the snapshot is null if the navigation is not yet started or has already been stopped.

Next steps

Since you have learned about our modular architecture, here are recommendations for the next steps:

• Free driving
• Continuous replanning
• Location tracking