Re: [WoT-IG]: Comments on proposed charter for WoT WG

> On 2 Apr 2016, at 00:15, Kovatsch, Matthias <matthias.kovatsch@siemens.com> wrote:
> 
> Von: Dave Raggett [mailto:dsr@w3.org <mailto:dsr@w3.org>] 
> 
> I would very much like to hear from the IG what exactly is meant by “URI mappings for non-resourceful protocols”.
>  
> Correct wording will be tricky on this one: A “resource is anything that can be identified by a URI”, but many protocols do not call their data endpoints a resource, but it is still possible to come up with URIs to identify and address them. Thus, “non-RESTful” might be a bit closer.
>  
> Anyhow, the intention is to define URIs that can address data elements (or “interaction” elements in TD terms) in IoT protocols that do not have URIs (yet), for instance, an attribute in GATT/BLE or a topic in MQTT. A URI is basically just a string that identifies the protocol through the scheme and then more information that can be used to encode protocol-specific addressing information.
>  
> When a client has the necessary protocol stack, it can contact the interaction element described by the TD through the URI directly. If not, it can pass this URI to a proxy (e.g., using the CoAP Proxy-URI option or HTTP proxying through the Request-Line), which will then make the request in that protocol on behalf of the client. This kind of proxy is application-agnostic (it does not know anthing about WoT, TD, and interactions, but only the two or more protocols).
>  
> Does the idea become clearer?

A little, so we definitely need clearer wording for the charter.  At the abstract messaging level, there is a need to express paths in terms of thing data models, e.g. a property might be an array of values, and you want to update the third value in the array. Different protocols could represent such path identifiers in different ways. For instance, a protocol could involve an exchange of JSON messages over Web Sockets. These messages could use a path string to identify what a value update applies to. For those protocols that use URIs for identifiers, we will need a way to map paths for thing data models into the corresponding URIs. The conventions for this form part of the protocol binding specifications.

I am left confused as exactly what you want to rule out of scope and why?  Is it to do with steering clear of IPR concerns? What is your test for whether a protocol is resourceful or not?

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