Re: Improving EXISTS

On 26/06/16 13:07, james anderson wrote:
> good afternoon;
>
>> On 2016-06-25, at 17:58, Andy Seaborne <andy@apache.org
>> <mailto:andy@apache.org>> wrote:
>>
>> The tests contributed by Peter and the discussions around them show
>> that there are bugs in the spec.
>>
>> The RDF Shapes working group uses EXISTS and also uses "pre-binding"
>> which is a form of parameterized query(*) in SHACL [1] and the EXISTS
>> mechanism is related to parametrization.
>>
>> W3C process for corrections to recognized generally to be inflexible.
>> It is normally to wait for the next WG to run and end which is a
>> multiyear cycle - that does not fit with the RDF Shapes WG timescale.
>>
>> A suggestion (from Arnaud Le Hors / RDF Shapes chair, as well as other
>> people) is to use the Community Group mechanism to build consensus in
>> the SPARQL community, including implementers and users.
>>
>> Community Groups can publish reports. These are not W3C standards.
>> They do provide a way to record consensus or alternatives. This could
>> be used to supplement the SPARQL errata process [2].
>>
>> Whether that is a specific CG for this one task, or using "RDF Tests"
>> is a matter of refinement - for me, I prefer which ever one looks like
>> it creates the better community.
>>
>> Thoughts and comments?
>
> - request parameters are a de facto requirement, as they were
> established by sesame and now users expect them.
> if there is to be an effort to ratify a standard behaviour, that
> deserves a group of its own, independent of any concern for shapes
> and/or exists.

Certainly useful and important.

My preference is for a quite tightly focused CG mainly so it knows when 
it's finished and we can see if the approach of using CG's is viable. 
The biggest factor I see is lack of people's time.

There is nothing to preclude another one.  Nor of making a proposal to 
public-sparql-dev@w3. There choices for protocol-parametrized queries 
such as it just one set of name/values injected or a table of?

> - as to exists itself, its semantics is underspecified and a working
> group tasked with its definition would be worth while.
> the charter should include any possible changes in the clause syntax and
> the run-time semantics, but should avoid any suppositions as to
> implementation.

Changing the syntax is a last resort - I think we can at least give ore 
detail to current syntax. of course, if implementations want to add 
syntax, discussing/documneting/(even agreeing!) that would be good.

>
> - once the semantics is defined, the rdf test group should proceed to
> define and ratify tests.

Agreed.

	Andy

>
> best regards, from berlin,
>
>
> ---
> james anderson | james@dydra.com <mailto:james@dydra.com> | http://dydra.com
>
>
>
>
>

Received on Wednesday, 29 June 2016 15:13:21 UTC