The ResourceUri parameter of DataType String enables the transport implementation to look up a configured key from the corresponding KeyCredentialConfigurationType instance defined in OPC 10000-12 to use for authenticating access to the Broker at the connection level or for queues configured below the connection.

The ResourceUri should uniquely identify a user and broker combination in a Publisher. An example for such a Uri is “mqtts://myuser@mydomain.com:8883”.

If null or empty, no authentication or anonymous authentication shall be assumed as default unless authentication settings are provided on a subordinated WriterGroup or a DataSetWriter to authenticate access to individual queues.