MQTT Transmit

A mqtt data transmit transfers data to the mqtt broker.

Example:

If we want to upload our records from the bathhouse:water stream to our IOT cloud, broker.emqx.io with port 1883 our configuration will look something like this:

{
    "data_transmit": [
        {
            "transmit_name": "iot_hub_transmit",
            "transmit_type" : "mqtt",
            "filter_stream": [
                "bathhouse:water"
            ],
            "host": "broker.emqx.io",
            "port": 1883,
            "username": "spiderman",
            "password": "somepowerfullpass",
            "topic": "some_topic",
            "client_id": "some_client_id"
        }
    ]
}

Warning:

This plugin is very sensitive to upload bandwidth: if it can’t upload a payload completely within the timeout, it will abort the connection and try again. You may need to increase the timeout from the default of two minutes. For example:

{
    "transmit_name": "SightMachine",
    "transmit_type": "mqtt"
    "filter_stream": ["*"],
    "timeout": 300
}

Configuration:

Required and optional properties that can be configured for an MQTT transmit:

• host: MQTT broker hostname (e.g. broker.emqx.io)
• port: MQTT connection port (Currently defaults to 1883)
• client_id: Some unique string identifying the client to the MQTT server. Must be unique across all connections to the MQTT server.
• username: Username to connect to the server
• password: Password to connect to the server
• topic: topic where we send MQTT messages
• additional_fields: additional field to add in the message payload for e.g. { “processingPath”: “SM”}
• transmit_name: ID for the transmit. It must be unique.
• transmit_type: Method to use in transmitting records.
• filter_stream: A list of streams that will use the transmit. Each stream can either be * (all) or asset:stream.
• timeout: Number of seconds to wait until timing out.
• poll_interval: Maximum number of seconds to wait between requests
• max_request_records: Maximum number of records to send in a single request.
• max_request_size_bytes: Maximum number of bytes allowed in a single request. Size is capped at 4 MB.
• opc_payload_metadata: Additional fields to add in the OPC-formatted payload. E.g. { “TiqTwin”: { “NodeId”: “a2ec725a-78e2-431b-a124-ce20b8e3e4c6” }} Ignored if use_opc_publisher_format is False.
• opc_message_metadata: Per-message metadata fields to add in the OPC-formatted payload.
• use_opc_publisher_format: If True, the message payload will be formatted to mimic OPC Publisher. https://github.com/Azure/Industrial-IoT/tree/main/docs/opc-publisher#opc-publisher-telemetry-formats