Re: [TF-TD] Meeting minutes + Update TD Tutorial

The idea that came up in the call was to have something in a Thing
Description that might indicate the volatility of the resource state.
(Expressing this in the inverse, as stability, has the advantage that we
can use more handy periods in seconds.)

Some resources actually only provide a new value periodically.
E.g., I have a CO2 sensor that needs about five seconds for a
measurement, so even if you ask it every second, you get five times the
same value before it is updated again.

Some resources measure a slow-moving quantity (e.g., barometric pressure
in an weather station).  While it is less obvious what a good value for
stability would be here, many sensors actually have an internal
averaging window to reduce the noise from the measurement.

Some resources do not per se have a value for stability, e.g. a light
switch might have the same value for a day, and then get pressed twice
within a second.  Here we could still encode user expectations, e.g. the
expectation that a button press will lead to a result within 200 ms.

Note that in all cases we still have MaxAge (in CoAP, or one of several
equivalents in HTTP) for an actual current value with each GET; the
Thing Description would only provide an expected value.

Grüße, Carsten


Takuki Kamiya wrote:
> Hi,
> 
>  
> 
> How does “stability” helps other than the case of the value 0?
> 
>  
> 
> For example, if the value is 10 seconds, clients know the value
> 
> is obsolete after 10 seconds passed. However, it is also likely that
> 
> the value has already changed after 8 seconds passed, for instance.
> 
> Then the client may want to check the property value even before
> 
> 10 seconds passed.
> 
>  
> 
> Thank you,
> 
>  
> 
> Takuki Kamiya
> 
> Fujitsu Laboratories of America
> 
>  
> 
>  
> 
> *From:*Kaebisch, Sebastian [mailto:sebastian.kaebisch@siemens.com]
> *Sent:* Friday, September 04, 2015 2:07 AM
> *To:* public-wot-ig@w3.org
> *Subject:* [TF-TD] Meeting minutes + Update TD Tutorial
> 
>  
> 
> Dear TD and WoT members,
> 
>  
> 
> please find the meeting minutes of Wednesday's web meeting here [1] or
> at the TD wiki page [2] (thanks to Dave for scribing).
> 
>  
> 
> The TD tutorial [3] contains some updates:
> 
> ·         As discussed in the web meeting, the Property contains a new
> optional member “stability” to characterize how stable or dynamic the
> property is (please comment on it)
> 
> ·         The LED example contains two new dim-able based actions:
> “fadeIn” and “fadeOut” 
> 
> ·         At the end of the tutorial there is the current discussion
> about the CoAP binding approach with and without HATEOAS.
> 
>  
> 
> Any feedback is welcome!
> 
>  
> 
> Please note that the next meeting will take place on 16th of September
> at 3pm CEST. I forgot to mention that Darko Anicic will organize and
> moderate the next 2 web meetings. I will be on parental leave until
> middle of October.
> 
>  
> 
> Best wishes
> 
> Sebastian
> 
>  
> 
>  
> 
> [1] http://www.w3.org/2015/09/02-wot-td-minutes.html
> 
> [2] https://www.w3.org/WoT/IG/wiki/Thing_Description#Minutes
> <https://www.w3.org/WoT/IG/wiki/Thing_Description>
> 
> [3] https://github.com/w3c/wot/blob/master/TF-TD/Tutorial.md
> 
>  
> 
>  
>

Received on Saturday, 5 September 2015 03:10:12 UTC