Equivalent usage in WoT TD

unitdescription(s)title(s)…

Description

HasProperty references in OPC UA are typically used to provide static information about a node. This information are properties of a node that do not change frequently and provide useful metadata or context information.

The TD provides terms such as unit, title(s), descriptions(s), etc. to annotate, e.g., properties and actions with additional information. Also additional terms from other ontologies can be used to make additional annotations in TDs. Depending of the purpose of the provided HasProperty variable, a corresponding mapping can be processed into the TD. E.g., unit information can be mapped to the unit term or descriptions can be mapped to the description or descriptions (multi languages text) term.

Snippet example in OPC UA (e.g., as nodeset)

…<UAVariable NodeId="ns=1;s=Temperature" BrowseName="1:Temperature" DataType="Double" ValueRank="-1">

<DisplayName>Temperature</DisplayName>

<References>

<Reference ReferenceType="HasTypeDefinition">AnalogItemType</Reference>

<Reference ReferenceType="HasProperty">ns=1;s=Temperature_Unit</Reference>

</References>

</UAVariable>…

<UAVariable NodeId="ns=1;s=Temperature_Unit" BrowseName="1:Unit" DataType="String" TypeDefinition="PropertyType">

<DisplayName>Unit</DisplayName>

<Value>

<String>Celsius</String>

</Value>

</UAVariable>

Transformed usage in a TD definition (as snippet)

…

"properties": {

"1:Temperature": {

"@type" : ["AnalogItemType"],

"type":"number",

"unit":"Celsius",

…