Behavior of affordances

[danielpeintner]

@egekorkan mentioned during todays TPAC meeting that the Scripting API taskforce might want to look into the following aspects:

What is the behavior/result of some affordances?

He was pointing at the web-thing-protocol that has notes for some of the expected behaviors.
e.g.,

Personally, I am not sure if it is really a scripting topic. I think it goes way beyond scripting. What do others think?

Anyhow, having guidance/rules or a way to clarify what a certain affordance may trigger seems reasonable.
It may differ depending on the binding also...

What is the right place to work on it?

[egekorkan]

Thanks for the issue. Indeed we have nowhere saying what is the behavior of readproperty. Scripting API gets into it at https://w3c.github.io/wot-scripting-api/#the-readproperty-method for example. Similarly, webthing protocol also talks about such stuff.

I will copy paste some text from readproperty from both documents, omitting some stuff but not changing:

Scripting API:

• link to section
• link to section
• text1: Make a request to the underlying platform to retrieve the value of the propertyName Property using form and the optional URI templates. Let response be the response received to the request.
• text2: The handler ... should implement reading a Property and SHOULD be called by implementations when a request for reading a Property is received.

webthing:

• link to section
• text1: To request a property reading from a Thing, a Consumer MUST send a message to the Thing which contains the following members.
• text2: When a Thing receives a message from a Consumer with messageType set to request and operation set to readproperty it MUST attempt to read the value of the Property with the given name.

[danielpeintner]

Scripting API call 2025-11-26

• Some advice can/should be given in the TD (@egekorkan do you agree?)
• Some rules relate to the actual binding (and should be offloaded to it). What happens if protocol differ and an application is not agnostic of the protocol in use...
• Case by case: difficult to come up with all possible situations
• Point 7 of readproperty should link to it
• Architecture describes the Interaction Model which could contain such information

[egekorkan]

TD Call:

• Bringing this to the Main Call is probably needed. There is no easy solution other than moving the whole interaction model explanation to the TD spec.
• The bindings would behave differently so we cannot mandate a single mechanism for all, some exceptions etc. needs to be explained.