Re: IOTDB: modeling state

> On 2 Jun 2015, at 19:27, David Janes <davidjanes@davidjanes.com> wrote:
> 
> You always need to know when a property value has taken effect if you're presenting a user interface. e.g. an interface can't tell a user that the light has turned off when they can clearly see that it's still on! Instead the interface has to indicate that the system is in a transitioning state.

Why?  In a distributed system, you can expect some lag although it could be quite small.  In a well designed system, this won’t be a problem.  If you as a designer know that there will be a long lag then you should design the system and the user experience accordingly.

It would be very helpful if you could give specific use cases that clarify the issue.  I would like to hear more about the specific IoT systems that you’re thinking about, and why it takes so long from issuing a command to the change in the physical state.   The examples, I have seen, e.g. changing the brightness/hue of a light, or moving a servo, all seem to take place pretty quickly.  Rather than talking in the abstract, let’s talk about concrete instances.

—
   Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>>