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Creating a trigger that sends messages to WebSocket connections from an Yandex IoT Core registry or device topic

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Updated at November 14, 2024

Create a trigger for an Yandex IoT Core registry or device topic and send message copies to WebSocket connections.

Warning

The trigger must be in the same cloud as the registry or device whose topic it reads messages from.

Getting started

To create a trigger, you need:

  • API gateway. Messages will be sent to WebSocket connections connected to the API gateway. If you do not have an API gateway, create one.

  • Service account with the api-gateway.websocketBroadcaster role. If you do not have a service account, create one.

Creating a trigger

Note

The trigger is initiated within 5 minutes of being created.

  1. In the management console, select the folder where you want to create a trigger.

  2. Open API Gateway.

  3. In the left-hand panel, select Triggers.

  4. Click Create trigger.

  5. Under Basic settings:

    • Enter a name and description for the trigger.
    • In the Type field, select IoT Core (device).
    • In the Launched resource field, select API gateway.

  6. Under IoT Core message settings, specify the registry, device, and MQTT topic to create a trigger for. When creating a trigger for a registry topic, you do not need to specify a device or an MQTT topic. If no MQTT topic is set, the trigger fires for all registry or device topics.

  7. Under Batch message settings, specify:

    • Batch size. The values may range from 1 to 1,000. The default value is 1.
    • Maximum wait time. The values may range from 1 to 60 seconds. The default value is 1 second.

    The trigger groups messages for a period not exceeding the specified wait time and sends them to WebSocket connections. The number of messages cannot exceed the specified batch size.

  8. Under API gateway settings:

    • In the API gateway field, select the API gateway.
    • In the Path field, specify the path in the OpenAPI specification. Messages will be sent through WebSocket connections established using this path.
    • In the Service account field, select the service account to send messages to WebSocket connections.

  9. Click Create trigger.

If you do not have the Yandex Cloud command line interface yet, install and initialize it.

The folder specified in the CLI profile is used by default. You can specify a different folder using the --folder-name or --folder-id parameter.

To create a trigger that sends messages to WebSocket connections, run this command:

yc serverless trigger create internet-of-things \
  --name <trigger_name> \
  --registry-id <registry_ID> \
  --device-id <device_ID> \
  --mqtt-topic '$devices/<device_ID>/events' \
  --batch-size <message_group_size> \
  --batch-cutoff <maximum_timeout> \
  --gateway-id <API_gateway_ID> \
  --gateway-websocket-broadcast-path <path> \
  --gateway-websocket-broadcast-service-account-id <service_account_ID>

Where:

  • --name: Trigger name.
  • --registry-id: Registry ID.
  • --device-id: Device ID. If you are creating a trigger for a registry topic, you can omit this parameter.
  • --mqtt-topic: MQTT topic you want to create a trigger for. This is an optional parameter. If this parameter is skipped, the trigger fires for all registry or device topics.
  • --batch-size: Message batch size. This is an optional parameter. The values may range from 1 to 10. The default value is 1.
  • --batch-cutoff: Maximum wait time. This is an optional parameter. The values may range from 0 to 20 seconds. The default value is 10 seconds. The trigger groups messages for a period not exceeding batch-cutoff and sends them to WebSocket connections. The number of messages cannot exceed batch-size.
  • --gateway-id: API gateway ID.
  • --gateway-websocket-broadcast-path: Path in the OpenAPI specification. Messages will be sent through WebSocket connections established using this path.
  • --gateway-websocket-broadcast-account-id: Service account ID with permissions to send messages to WebSocket connections.

Result:

id: a1s5msktijh2********
folder_id: b1gmit33hgh2********
created_at: "2022-10-24T15:19:15.353909857Z"
name: iot-trigger
rule:
  iot_message:
    registry_id: arenou2oj4h2********
    device_id: areqjd6un3h2********
    mqtt_topic: $devices/areqjd6unh2********/events
    batch_settings:
      size: "1"
      cutoff: 0s
    gateway_websocket_broadcast:
      gateway_id: d4eofc7n0mh2********
      path: /
      service_account_id: aje3932acdh2********
status: ACTIVE

To create a trigger for Yandex IoT Core, use the create REST API method for the Trigger resource or the TriggerService/Create gRPC API call.

Checking the result

Check that the trigger operates correctly. Do it by viewing the API gateway logs that present information about its incoming requests.

See also

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