OPCFoundation.NetStandard.Opc.Ua.WotCon.Bindings.Mqtt

OPC UA WoT Connectivity — MQTT Executor

OPCFoundation.NetStandard.Opc.Ua.WotCon.Bindings.Mqtt executes MQTT WoT Connectivity binding forms compiled by the MQTT planner in Opc.Ua.WotCon.Bindings.

It uses the repository's MQTTnet infrastructure (kept out of the core model assembly) to implement publish / subscribe / RPC patterns per the pinned MQTT binding, with bounded QoS, topic, payload sizes and timeouts. The MQTT client factory is injectable.

Transport security

• An mqtts:// href always enables TLS and defaults to port 8883; an mqtt:// href stays explicit plaintext (port 1883). There is no silent plaintext downgrade.
• Username / password credentials, the TLS client certificate and the TLS trust anchors are resolved through the registered IWotCredentialProvider. A form that declares a security scheme fails closed (the connection is refused) when the provider resolves no credential.
• Username / password credentials are refused over a plaintext mqtt:// connection unless MqttWotBindingOptions.AllowCredentialsOverPlaintext is set for an explicitly accepted plaintext deployment. ValidateServerCertificate controls broker-certificate validation for mqtts://.

Register it with builder.AddMqttWotBinding(...).

The package targets net8.0, net9.0, and net10.0. The MQTT planner and common binding contracts are supplied by OPCFoundation.NetStandard.Opc.Ua.WotCon.Bindings.

See the WoT protocol bindings guide.