Re: Proposal for a WoT servient based on IoTivity

> On 25 Jun 2016, at 19:45, Michael Koster <michael.koster@smartthings.com> wrote:
> 
> Capabilities solve a use case need for reusable semantic definitions of properties, actions, and events. For example, if I have a thing with more than one function that offers on/off control, I need some way to associate a particular on/off instance to the instance of the thing that it controls. 

I’ve looked at this in terms of being able to define a type and then refer to it, just as you would use typedef in C++. See: 

     https://github.com/w3c/web-of-things-framework/blob/master/documents/json-td.md

This provides an example for properties, but could equally be applied to actions and events.

I believe that it is important to decouple the formal model of types from the serialisation format we used to transmit the definitions, so that the web of things isn’t tied to one representation, see:

     https://github.com/w3c/web-of-things-framework/blob/master/documents/types.md

A related topic is modularity of semantic models and domain constraints. This group hasn’t take much of an interest in this as yet, but semantic models are important when it comes to enabling interoperability based upon shared meaning.

We also need to look further at how to combine generic descriptions for a class of device, with the metadata specific to that device.  For instance, I have an IoT device that supports ZigBee.  This is discovered and paired with a gateway.  This gateway consults a cloud service to get the thing description for this class of IoT device (e.g. a thermostat) and registers the thing declared in the description with a cloud server using a thing description specific to this particular instance of the class of devices.

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