Broker connection in SparkplugCmd utility

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The primary means of specifying the broker connection in the SparkplugCmd is the resourceDescriptor arguments to commands such as consumer or edgeNode. The resourceDescriptor is an URL of the broker, and it defaults to "mqtt://localhost", which specifies a non-authenticated TCP connection to the MQTT broker residing on the local machine, using port 1883. For further information on the URL syntax in resourceDescriptor, and the configurable parameters of the MQTT channel, see OpcLabs.MqttNet communication package.

Authentication

The username and password can be specified in the MQTT broker URL. Note that the username and password are transferred in plain text on the wire, unless encryption is used (e.g., using TLS or WSS).

Examples

Example URL with authentication: mqtt://admin:password@localhost

Subscribing to Sparkplug payloads, with authentication:

consumer mqtt://ro:readonly@test.mosquitto.org:1884 
subscribePayload

Sparkplug edge node publishing with authentication:

edgeNode mqtt://wo:writeonly@test.mosquitto.org:1884 
start

MQTT 5

The MQTT protocol version can be specified in the broker URL using the "version" query parameter. Possible values are 310, 311, and 500, which correspond to MQTT 3.1, MQTT 3.1.1, and MQTT 5.0, respectively. The default is MQTT 3.1.1.

Examples

Example URL: mqtt://localhost?version=500

TLS

The TLS protocol can be specified in the broker URL using the "mqtts", "ssl" or "tls" scheme (the schemes are equivalent). Default port is 8883. TLS can be combined with username/password authentication.

SparkplugCmd uses a Certificate security plugin with console interaction turned on by default. This means that when an unknown remote certificate is provided by the broker, SparkplugCmd will ask the interactive user whether the certificate should be accepted or not.

Examples

Example URL: mqtts://localhost

Subscribing to Sparkplug payloads, with TLS:

consumer mqtts://test.mosquitto.org
subscribePayload

WebSocket

The WebSocket protocol can be specified in the broker URL using the "ws" scheme. Note: Use the "wss" scheme for WebSocket Secure. Default port for "ws" is 80, and for "wss" is 443.

Examples

Example URL: ws://localhost:8080/mqtt

Subscribing to Sparkplug payloads, over WebSocket:

consumer ws://test.mosquitto.org:8080
subscribePayload

See also

• OpcLabs.MqttNet communication package
• Using SparkplugCmd Utility as Sparkplug Edge Node
• Using SparkplugCmd Utility as Sparkplug host application