The server gives an error (example server file)

[akrutovs]

main.go.txt
I use uaexpert to check the health of the server. When I run the main.go code for the first time, the server starts without errors, then I connect to it using uaexpert and see the value I need, but at this time the console receives a lot of errors (photo 1). After I disconnect the server and start it again without closing and breaking the connection with uaexpert and the server does not start and gives an error (photo 2). Please help, what am I doing wrong? Maybe there is an extended example of using the server with setting attributes and signal statuses?

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[danomagnum]

I'll investigate and let you know what I find. Certainly the server should not crash when it starts with a client tries to use a session id from the previous run.

[danomagnum]

Looks to me like this was a side-effect of the switch to DataValues across the board - it was wrapping a function that returns *DataValue in another function that returns a *DataValue.

I think I got it fixed as part of some access level feature work. Try the server_accesslevels branch and see if it is fixed.

go get github.com/gopcua/opcua@server_accesslevels

[akrutovs]

I also found my mistake

// Add a tag.
	val := ua.DataValue{
		Value: ua.MustVariant(float32(123.2)),
		Status: ua.StatusBad,
		SourceTimestamp: time.Now(),
		EncodingMask: ua.DataValueValue | ua.DataValueStatusCode | ua.DataValueSourceTimestamp,
	}
	n := tagNS.AddNewVariableNode(“Voltage”, val)

I passed the value of Val to the AddNewVariableNode function instead of a pointer to this variable, it was strange that it worked without a connected client and didn't work with a connected one.

I also found that after restarting the server with a connected client, the data in uaExpert does not match the DisplayName.
I will describe in more detail:
I have a set of DisplayName (200 pieces) each time I start the server I add them from Map so the order of addition is different, respectively the server when restarting the same displayname gives different Node IDs

At the first start of the server (with disabled client) and connecting UaExpert to it, the data is correct (Displayname, node id and value are displayed correctly) (photo 1).

After restarting the server already with the connected client Node ID changes for the same Displayname and the data values for Displayname are not correct, I am not sure whose side is the error, either UaExpert does not update the correspondence of NodeID with DisplayName, or this implementation should be in my code or in the library code, if you know the answer, please tell me. (photo2)

[danomagnum]

The subscriptions are tied to the node ID and not the display name. So if you assign different data to the same node ID, I would expect the values to change like they are I think. If I'm understanding properly, it looks like node 157 changed from "30505" to "320006". So if something was writing a value to 157, it would be writing to the wrong place now.

If you care about what node ID is assigned to each node, you might want to use string node IDs instead of numeric node IDs. You should be able to use AddNewVariableStringNode instead of AddNewVariableNode.

If that's not the issue, could you put together a minimal reproducible example?