It is assumed that basic concepts of OPC UA information modelling and W3C Web of Things are understood in this document. This document will use these concepts to describe the Web of Things for OPC UA Information Model. For the purposes of this document, the terms and definitions given in OPC 10000-1, OPC 10000-3, OPC 10000-4, OPC 10000-5, as well as the following apply.

Note that OPC UA terms and terms defined in this document are italicized in the document.

Protocol Binding

Part of Web of Things Thing Description describing the communication interface as well as the data “tags” available in an asset.

SOURCE: https://w3c.github.io/wot-architecture/#dfn-wot-protocol-binding

JSONJavaScript Object Notation

URIUniform Resource Identifier

WoTWeb of Things

TDWeb of Things Thing Description

The NodeIds of all Nodes described in this standard are only symbolic names. Annex A defines the actual NodeIds.

The symbolic name of each Node defined in this document is its BrowseName, or, when it is part of another Node, the BrowseName of the other Node, a “.”, and the BrowseName of itself. In this case “part of” means that the whole has a HasProperty or HasComponent Reference to its part. Since all Nodes not being part of another Node have a unique name in this document, the symbolic name is unique.

The NamespaceUri for all NodeIds defined in this document is defined in Annex A. The NamespaceIndex for this NamespaceUri is vendor-specific and depends on the position of the NamespaceUri in the server namespace table.

Note that this document not only defines concrete Nodes, but also requires that some Nodes shall be generated, for example one for each Session running on the Server. The NodeIds of those Nodes are Server-specific, including the namespace. But the NamespaceIndex of those Nodes cannot be the NamespaceIndex used for the Nodes defined in this document, because they are not defined by this document but generated by the Server.

The text part of the BrowseNames for all Nodes defined in this document is specified in the tables defining the Nodes. The NamespaceUri for all BrowseNames defined in this document is defined in 8.2.

For InstanceDeclarations of NodeClass Object and Variable that are placeholders (OptionalPlaceholder and MandatoryPlaceholder ModellingRule), the BrowseName and the DisplayName are enclosed in angle brackets (<>) as recommended in OPC 10000-3.

If a BrowseName is not defined by this document, a namespace index prefix is added to the BrowseName (e.g., prefix '0' leading to ‘0:EngineeringUnits’ or prefix '2' leading to ‘2:DeviceRevision’). This is typically necessary if a Property of another specification is overwritten or used in the OPC UA types defined in this document. provides a list of namespaces and their indexes as used in this document.

The Attributes of Nodes, their DataTypes and descriptions are defined in OPC 10000-3. Attributes not marked as optional are mandatory and shall be provided by a Server. The following tables define if the Attribute value is defined by this document or if it is server-specific.

For all Nodes specified in this document, the Attributes named in Table 1 shall be set as specified in the table.

Table 1 – Common Node Attributes

Attribute	Value
DisplayName	The DisplayName is a LocalizedText. Each Server shall provide the DisplayName identical to the BrowseName of the Node for the LocaleId “en” unless specified differently in the specification. Whether the Server provides translated names for other LocaleIds is server-specific.
Description	Optionally a server-specific description is provided.
NodeClass	Shall reflect the NodeClass of the Node.
NodeId	The NodeId is described by BrowseNames as defined in 3.4.1.1.
WriteMask	Optionally the WriteMask Attribute can be provided. If the WriteMask Attribute is provided, it shall set all non-server-specific Attributes to not writable. For example, the Description Attribute may be set to writable since a Server may provide a server-specific description for the Node. The NodeId shall not be writable, because it is defined for each Node in this document.
UserWriteMask	Optionally the UserWriteMask Attribute can be provided. The same rules as for the WriteMask Attribute apply.
RolePermissions	Optionally server-specific role permissions can be provided.
UserRolePermissions	Optionally the role permissions of the current Session can be provided. The value is server-specific and depends on the RolePermissions Attribute (if provided) and the current Session.
AccessRestrictions	Optionally server-specific access restrictions can be provided.

For all Objects specified in this document, the Attributes named in Table 2 shall be set as specified in the Table 2. The definitions for the Attributes can be found in OPC 10000-3.

Table 2 – Common Object Attributes

Attribute	Value
EventNotifier	Whether the Node can be used to subscribe to Events or not is server-specific.

For all Methods specified in this document, the Attributes named in Table 3 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.

Table 3 – Common Method Attributes

Attributes	Value
Executable	All Methods defined in this document shall be executable (Executable Attribute set to “True”), unless it is defined differently in the Method definition.
UserExecutable	The value of the UserExecutable Attribute is server-specific. It is assumed that all Methods can be executed by at least one user.