Value dependent Affordances

[egekorkan]

Note: In parentheses, I am providing an alternative user story about the same feature

• Who (As a...): Device Manufacturer (as a Consumer Application)
• What (I need...): Indicate in our TDs and TMs that some data ranges are dependent on the values of properties (Avoid displaying wrong value ranges in some states of the Thing I am communicating with)
  • Details: This is very common in devices where an electric motor can be wired in delta or wye formation (https://en.wikipedia.org/wiki/Y-%CE%94_transform). Once the wiring is done, the operator sets a configuration property to a string. If that property returns delta, the voltage minimum-maximum is simply the line voltage. If that property returns wye, the maximum is line voltage divided by sqrt(3).
• Why (so that I can...): Make sure that Consumer applications read a property value before finding the value ranges of the other properties (Read the relevant property to understand different ranges and display them correctly on a dashboard or do appropriate input checking)

Notes:

• There is a variation of this user story where a property needs to be read before an action can be invoked. This was shown in the last WoT CG meetup presentation by @VigneshVSV (see around time linked time at https://youtu.be/k2KMKd2ZVq0?si=09C4zX52cHuwCiJ7&t=2024). A more correct modeling would be via something like SCXML or XState, where some initial work by @FadySalama is available at https://github.com/tum-esi/Stateful-WoT, which also shows an example of a motor driver from Schneider Electric.