Re: YANG inspirations for TD

Thanks for your time and responces Dave.

Regards
Robert

On Mon, Oct 3, 2016 at 3:19 PM, Dave Raggett <dsr@w3.org> wrote:

>
> On 3 Oct 2016, at 12:27, Robert Gallas <gallas.robert@gmail.com> wrote:
>
> Hi Dave,
>
> I have made post in relation to https://github.com/w3c/wot/
> tree/master/proposals/td-restructuring
>
> By interaction type I mean property/event/action. Proposed version is
> similar of how YANG works with its properties, event streams and rpc's.
>
> Thanks for remainding me of commerciall UC's. Sometimes I do not take it
> into account. In this case I'm influenced by networking environment. If
> term IoT/WoT is used not only for sensors and actuators but at the sense of
> Every/Any-thing then network devices are next WoT candidates. Not all of
> the network devices use formalized model, but if they use - it is YANG.
> Network devices are modeled by  very complex data model with constraints
> like min/max in mind. It is heavily used in Software Defined Networking
> (SDN) area. There is also translation between YANG and REST. Point is that
> YANG is mature and used in production so I think it could be valuable to
> have yet another source of knowledge and inspiration.
>
> For me the way how to model data seems tricky. The most sensitive part is
> how complex The Thing can become and this comes in response to what is and
> what is not the use case for WoT. If WoT can also be services and network
> devices, requirements for data modeling can become way too complex - SOAP -
> XSD, YANG etc. As well as to have possible model to model translation.  But
> that is out of scope for this thread.
>
>
> Things in the web of things can be any physical or abstract entity, and
> thus range from really simple use cases to complex ones. For the web of
> things it is important to decouple how applications interact with things
> from the underlying protocols. We therefore need to focus on the data
> models exposed to applications via the interfaces for properties, actions
> and events. I agree with the need to be able to express constraints, and we
> could introduce simple ones in the initial standard, and add richer ones as
> we reach a consensus as to what is needed. I also see a need to support
> late binding, e.g. where you don’t know the precise type until a value has
> been passed through an interface. Semantic models can provide richer models
> and complement the data type declarations, for instance a property could be
> declared as a number, whilst the semantic model declares it to be a
> temperature value in a given scale.
>
> To enable platforms to interoperate, we also need metadata describing the
> security and communications choices. This is where platform and protocol
> specific details are visible, e.g. the way that resources are exposed on a
> REST based server. This is the concern of platform developers and not aimed
> at app developers. However, app developers should be able to express
> communication requirements and to introspect what the platform has been
> able to offer in respect to those requirements.
>
> I suspect that web developers in particular will want representations that
> are both easy to understand and simple to express.  To put it another way
> simple use cases should be easy to express whilst more complex ones should
> still be practical, albeit more complex.
>
> Best regards,
>     Dave
>
>
> Robert
>
>
>
> On Mon, Oct 3, 2016 at 11:05 AM, Dave Raggett <dsr@w3.org> wrote:
>
>>
>> On 3 Oct 2016, at 07:41, Robert Gallas <gallas.robert@gmail.com> wrote:
>>
>> Hi all,
>>
>> There is and ongoing discussion about thing description (TD). I'd like to
>> point community to YANG modelling language (
>> https://tools.ietf.org/html/rfc6020 ) . YANG is built to address very
>> same requirements as TD. It has updatable properties, rpc`s, event streams,
>> data types etc.
>>
>> However even YANG is complex language and out of W3C standards it has
>> some interesting concepts which can serve as an inspiration for next TD
>> version. I mean mainly:
>>
>> - hierachical data model (helps in model maintainability and supports
>> contexts)
>> - value constraints (great help at UI generation, widget design and
>> reduces network traffic)
>> - interaction types concept (good for extensibility)
>>
>> Hope helps a bit.
>>
>> Robert
>>
>>
>> Hi Robert,
>>
>> Thanks for the input.  Could I kindly ask you for an explanation of what
>> you refer to as interaction types and how these differ from the data
>> models?  In addition, is it possible to point to the use cases and
>> requirements?  This would help the Working Group, as every feature needs to
>> be grounded in commercially relevant use cases.
>>
>> Many thanks,
>> —
>>    Dave Raggett <dsr@w3.org>
>>
>>
>>
>>
>
> —
>    Dave Raggett <dsr@w3.org>
>
>
>
>