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06/29/2023
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Hello,
Does OPC UA specification allow adding or deleting of Namespaces after the server has already started and Running? The specification Part3 9.32 is a bit ambiguous to me.
"ModelChangeEvents are generated to indicate a change of the AddressSpace structure. The change may consist of adding or deleting a Node or Reference. Although the relationship of a Variable or VariableType to its DataType is not modelled using References, changes to the DataType Attribute of a Variable or VariableType are also considered as model changes and therefore a ModelChangeEvent is generated if the DataType Attribute changes." - https://reference.opcfoundatio...../docs/9.32
"indicate a change of the AddressSpace structure." sounds like incuding Namespace changes, but later "he change may consist of adding or deleting a Node or Reference." talked about only Node and References.
05/30/2017
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Nodes and References can come and go on without changing Namespaces.
However, Namespaces can only be added only while a Server has at least one Client connected. A Server that no Clients connected can update the Namespaces used but it also does not generated ModelChangeEvents.
The specification is explicit here:
https://reference.opcfoundatio.....docs/6.3.1
It is recommended that Servers not change the indexes of the namespace table but only add entries, because the client may cache NodeIds using the indexes. Nevertheless, it might not always be possible for Servers to avoid changing indexes in the namespace table. Clients that cache NamespaceIndexes of NodeIds should always check when starting a session to verify that the cached NamespaceIndexes have not changed.
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