Namespaces are used by OPC UA to create unique identifiers across different naming authorities. The Attributes NodeId and BrowseName are identifiers. A Node in the UA AddressSpace is unambiguously identified using a NodeId. Unlike NodeIds, the BrowseName cannot be used to unambiguously identify a Node. Different Nodes may have the same BrowseName. They are used to build a browse path between two Nodes or to define a standard Property.
Servers may often choose to use the same namespace for the NodeId and the BrowseName. However, if they want to provide a standard Property, its BrowseName shall have the namespace of the standards body although the namespace of the NodeId reflects something else, for example the EngineeringUnits Property. All NodeIds of Nodes not defined in this document shall not use the standard namespaces.
Table 46 provides a list of mandatory and optional namespaces used in an Woodworking OPC UA Server.
Table 46 – Namespaces used in a Woodworking Server
|
NamespaceURI |
Description |
Use |
|
Namespace for NodeIds and BrowseNames defined in the OPC UA specification. This namespace shall have namespace index 0. |
Mandatory |
|
|
Local Server URI |
Namespace for nodes defined in the local server. This may include types and instances used in Woodworking machine represented by the Server. This namespace shall have namespace index 1. |
Mandatory |
|
Namespace for NodeIds and BrowseNames defined in OPC 10000-100 (OPC UA Devices). The namespace index is Server specific. |
Mandatory |
|
|
Namespace for NodeIds and BrowseNames defined in OPC 40001-1 (OPC UA Machinery). The namespace index is Server specific. |
Mandatory |
|
|
Namespace for NodeIds and BrowseNames defined in this document. The namespace index is Server specific. |
Mandatory |
Table 47 provides a list of namespaces and their indices used for BrowseNames in this document. The default namespace of this document is not listed since all BrowseNames without prefix use this default namespace.
Table 47 – Namespaces used in this document
|
NamespaceURI |
Namespace Index |
Example |
|
0 |
0:EngineeringUnits |
|
|
2 |
2:DeviceRevision |
|
|
3 |
3:YearOfConstruction |