Relationship between service resources
The main service elements are devices and registries. They can exchange various data and commands using the MQTT broker.
Data is exchanged via MQTT version 3.1.1. This simplified network protocol for device communication is based on the publisher/subscriber pattern. Registries and devices also interact using X.509 certificates. You can manage certificates from the Yandex CLI and Yandex IoT Core API.
Device
A device is an instance of a physical device, such as a temperature sensor, represented in the service as the device name and its certificate.
Devices are created in a registry. They can send telemetry data to the server, get commands, and interact with other devices in the registry.
Registry
A registry is a set of devices that are logically related to each other. Registries can read device data and send commands to them.
MQTT broker
The MQTT broker is the central node for exchanging MQTT messages between devices and registries. Data is only exchanged through the broker. It's responsible for receiving and processing messages and controls their delivery to clients (devices or registries) to ensure the necessary QoS.
Inside the service, devices and registries exchange data and commands as messages with specific topics.
Important
No additional settings are required for working with the MQTT broker integrated in the YC CLI (yc iot mqtt --help). If you use third-party libraries or applications (such as Mosquitto) as an MQTT broker, use the MQTT broker connection parameters.
QoS levels
When exchanging messages, Yandex IoT Core supports the following quality of service (QoS) levels for MQTT:
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QoS 0: At most once. A message is sent no more than once and there is no guarantee of delivery. -
QoS 1: At least once. This level guarantees that a message is delivered to a client at least once. There is a chance of receiving duplicate messages.
For more information about Yandex IoT Core service limits, see Quotas and limits.