Trigger for Yandex IoT Core that sends messages to WebSocket connections
A trigger for Yandex IoT Core manages messages exchanged between devices, registries, and brokers. It is created for topics: it receives copies of messages from the topics and sends the messages to WebSocket connections for processing.
The trigger must be in the same cloud as the device, registry, or broker whose topic it reads messages from.
You can create a trigger:
- For a standard topic implemented by the service except for the
$monitoring/<device_ID>/jsontopic. - For a topic with any subtopics and wildcards.
- For a topic alias.
A trigger for Yandex IoT Core requires a service account to send messages to WebSocket connections.
For more information about creating a trigger for Yandex IoT Core, see Creating a trigger that sends messages to WebSocket connections from a Yandex IoT Core registry or device topic and Creating a trigger that sends messages to WebSocket connections from a Yandex IoT Core broker topic.
Message batching
The batching settings allow sending several messages to WebSocket connections at a time. They set a top limit on a message batch size and its accumulation time. For example, if the message batch size is 3, WebSocket connections can receive batches containing from 1 to 3 messages.
Roles required for the proper operation of a trigger for Yandex IoT Core
- To create a trigger, you need a permission for the service account under which the trigger runs the operation. This permission comes with the iam.serviceAccounts.user and editor roles or higher.
- For the trigger to fire, the service account needs the
api-gateway.websocketBroadcasterrole for the folder containing the API gateway.
Read more about access management.
Yandex IoT Core trigger message format
Before sending a message copy to WebSocket connections, the trigger converts it to the format below.
Device
{
"messages": [
{
"event_metadata": {
"event_id": "2153b5d2-c6af-4c69-a28d-74ce********",
"event_type": "yandex.cloud.events.iot.IoTMessage",
"created_at": "2019-09-25T15:51:17.872320525Z"
},
"details": {
"registry_id": "arenou2oj4ct********",
"device_id": "areqjd6un3af********",
"mqtt_topic": "$devices/areqjd6un3af********/events",
"payload": "VGVz****"
}
},
{
"event_metadata": {
"event_id": "2153b5d2-c6af-4c69-a28d-74ce********",
"event_type": "yandex.cloud.events.iot.IoTMessage",
"created_at": "2019-09-25T15:51:17.872320525Z"
},
"details": {
"registry_id": "arenou2oj4ct********",
"device_id": "areqjd6un3af********",
"mqtt_topic": "$devices/areqjd6un3af********/events",
"payload": "VGVz****"
}
}
]
}
Broker
{
"messages":[
{
"event_metadata":{
"event_id":"2153b5d2-c6af-4c69-a28d-74ce********",
"event_type":"yandex.cloud.events.iot.IoTMessage",
"created_at":"2019-09-25T15:51:17.872320525Z"
},
"details":{
"broker_id":"arenou2oj4ct********",
"mqtt_topic":"broker/topic",
"payload":"VGVz****"
}
},
{
"event_metadata":{
"event_id":"2153b5d2-c6af-4c69-a28d-74ce********",
"event_type":"yandex.cloud.events.iot.IoTMessage",
"created_at":"2019-09-25T15:51:17.872320525Z"
},
"details":{
"broker_id":"arenou2oj4ct********",
"mqtt_topic":"broker/topic",
"payload":"VGVz****"
}
}
]
}