Uniqueness of NodeIds

[tobias-neubert]

Hi all, I hope this is the right place to ask such questions. I think it is an easy one: Does a NodeId have to be unique accross the whole tree of nodes?

I want to publish a set of values that are leaves of a tree of components, where each component provides the same values. Like so:

pool
|-- system1
  | -- component 1
    | -- value1
    | -- value2
    | -- ...
  | -- component 2
    | -- value1
    | -- value 2

I create a namespace containing that tree where the labels that you can see are the (local) ids of the nodes. That works and I can browse the tree in my test.

But if I want to write a value to a specific value node, I try to fetch that node from the UaNodeManager.getNode(), which saves alle nodes in a map keyed by their NodeIds. And in there there are only the last registered values nodes of my tree. So I assume, the NodeIds must be unique.

Am I right?

[tobias-neubert]

The server example seems to support my assumption: It prefixes all NodeIds with the parent id string.

[kevinherron]

Yes, NodeIds must be unique across the entire server.

[tobias-neubert]

Great thank you. Do you know if this is an implementation detail for milo or does the standard defines it this way? I am not sure. The only thing I found in https://reference.opcfoundation.org/Core/docs/Part3/5.2.2/ is this sentence: "Nodes are unambiguously identified using a constructed identifier called the NodeId."

[kevinherron]

It’s part of the standard, but I can’t readily find anything more explicit than the passage you found.

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On Oct 21, 2021, at 23:57, tobias-neubert ***@***.***> wrote:  Great thank you. Do you know if this is an implementation detail for milo or does the standard defines it this way? I am not sure. The only thing I found in https://reference.opcfoundation.org/Core/docs/Part3/5.2.2/ is this sentence: "Nodes are unambiguously identified using a constructed identifier called the NodeId." — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe.