reading multiple values as a structure

You can read multiple nodes by specifying an JSON of nodeId in the msg.nodeId or msg.topic attribute.

msg = {
    "topic": {
        "server": {             
            "status": "/Server/ServerStatus"
        },
        "device": {
            "temperature": "ns=1;s=Temperature",
            "pressure": "ns=1;s=Pressure"
        }
    },
    "attributeId": "Value",
    "outputType": "Value"
}

and the node will return the following message:

msg = {
    "payload": {
        "server": {
            "status": {
               ...
            },
            "temperature": 25.5,
            "pressure": 1.2
        }
    }
}

info

The JSON structure can be conveniently created the Explore OPC UA node.