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How to get node parent in uaServer
August 26, 2021
16:12, EEST
Forum Posts: 30
Member Since:
June 21, 2021
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Does the sdk provide a method to get a node’s parent in uaServer ?


August 27, 2021
9:20, EEST
Matti Siponen

Forum Posts: 151
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February 11, 2020
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First of all, OPC UA doesn’t have a strict parent-child hierarchy for Nodes. While you could say that a Node that targets another Node with a forward (non-inverse) Reference is the parent of the targeted Node, there could be other Nodes that also target the same Node making it possible for a Node to have multiple parents. And since there are multiple ReferenceTypes, the hierarchy of Nodes could look completely different for two different ReferenceTypes depending on the semantics of the used ReferenceTypes.

OPC UA Information Models use ParentNodeIds to express parent-child relationships between Nodes. However, the specification states (in https://reference.opcfoundation.org/Core/docs/Part6/F.7/) that “this information does not appear in the AddressSpace and is intended for use by design tools”, which is why there is no method that could be used to get this NodeId.

You could use UaNode.getReferences(NodeId referenceTypeId, boolean isInverse) where you specify a ReferenceType, e.g. HasComponent, with its NodeId, or use null for all ReferenceTypes, and set isInverse to true to get inverse References. Note, that the Prosys OPC UA SDK for Java handles all References internally as non-inverse References, which means that the UaNode that called the method is the target Node of the returned UaReferences! You could consider the source Nodes of the returned UaReferences as the parents of the UaNode.

October 12, 2021
14:44, EEST
Forum Posts: 30
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June 21, 2021
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