Configuration Management Extension service (CMX) extends Kaa Protocol (1/KP) and implements Configuration Management Protocol (7/CMP) to distribute configuration data to endpoints. As with other Kaa extension services, CMX uses Extension Service Protocol (4/ESP) for integration with a communication service.
CMX does not persist endpoint configuration data in any way—instead, configuration is pulled from an endpoint configuration data provider.
CMX implements a proactive configuration data push—endpoint configuration is sent to the endpoint as soon as possible, and an explicit endpoint subscription is not required. Note that explicit subscription is still recommended. To detect when a configuration push is required, CMX listens to some endpoint connectivity and lifecycle events defined in Endpoint Lifecycle and Connectivity Events (9/ELCE).
CMX supports a number of interfaces to perform its functional role. The key supported interfaces are summarized in the following diagram.
For inter-service communication, Kaa services mainly use REST APIs and messaging protocols that run over NATS messaging system.
EP configuration data transport
CMX acts as an endpoint configuration data consumer in line with 6/CDTP. This protocol is used to retrieve configuration data, update latest applied endpoint configuration, and listen to endpoint configuration update events.
CMX lets the endpoints check if new configuration is available and specify what configuration version they are currently using.
Extension service protocol
Endpoint lifecycle and connectivity events
CMX listens to endpoint lifecycle and connectivity events:
endpoint.lifecycle.appversion-updated. Change of application version may render other configuration applicable, which triggers a configuration push.
endpoint.connectivity.connected. If an endpoint has a new configuration available, it will be pushed as soon as the endpoint connects to the system.