14 Namespaces

14.1 Namespace metadata

Table 254, Table 255 and Table 256 define the namespace metadata for this document. Table 254 defines DataTypes that are shared between the AutomationComponent and the ConnectionManager. Table 255 defines the namespace associated with an AutomationComponent. Table 256 defines the namespace associated with a ConnectionManager. The Objects are used to provide version information for the namespaces and an indication of static Nodes. Static Nodes are identical for all Attributes in all Servers, including the Value Attribute. See OPC 10000-5 for more details.

The information is provided as an Object of type NamespaceMetadataType. This Object is a component of the Namespaces Object that is part of the Server Object. The NamespaceMetadataType ObjectType and its Properties are defined in OPC 10000-5.

The version information is also provided as part of the ModelTableEntry in the UANodeSet XML file. The links to the UANodeSet XML file are defined in Annex A. The UANodeSet XML schema is defined in OPC 10000-6.

14.2 Handling of OPC UA namespaces

OPC UA uses namespaces 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 defined outside of this document shall not use the standard namespaces defined in this document.

Table 257 provides a list of mandatory and optional namespaces used in a Server supporting OPC UA FX.

Table 258 provides a list of namespaces and their indices used for BrowseNames in this document. The NamespaceIndexes stated here are used as abbreviations throughout this document. Since NamespaceIndexes are dynamically assigned during the start of a Server, the NamespaceIndex, for example, for DI, may be different from 5 in a specific Server.