详细描述

Transport configuration for the mqtt:// MQTT protocol backend.

MqttConf configures the Eclipse Paho MQTT C transport, a lightweight publish/subscribe messaging protocol designed for constrained devices and low-bandwidth, high-latency networks.

Supported Node Types: mqtt:// supports all six node types: kPublisher, kSubscriber, kServer, kClient, kSetter, and kGetter.

URL Format: mqtt://<address>[?event=<name>&domain=<N>&qos=<0|1|2>][#<fragment>]

Component	Description
`address`	MQTT topic path; formed from `host` + `"/"` + `path`
`event`	Optional secondary event filter (?event=)
`domain`	Domain/namespace identifier (?domain=, default 0)
`qos`	MQTT QoS level: 0 (at most once), 1 (at least once), 2 (exactly once)
`fragment`	Optional broker URI override (e.g. `tcp://192`.168.1.1:1883)

Environment Variables

Variable	Description	Default
VLINK_MQTT_BROKER	MQTT broker URI	tcp://localhost:1883
VLINK_MQTT_DOMAIN	Default domain ID	0
VLINK_MQTT_QOS	Default QoS level (0, 1, 2)	1
VLINK_MQTT_KEEPALIVE	Keep-alive interval in seconds	60
VLINK_MQTT_CLIENT_ID	Client ID prefix	vlink_mqtt

注解: This header is compiled only when VLINK_SUPPORT_MQTT is defined.