Re: Anyone in support of SPARQL ASK constraints?

I don't have an opinion as to whether these should be kept or not but I 
have to say that I can relate to the difficulty you're reporting people 
have had with the fact that the return value is counter-intuitive. I feel 
the same with your proposal in general in that, essentially, instead of 
defining what is valid I actually have to define the error cases. I fully 
understand how you got there but I've always thought this was 
awkward/counter-intuitive.
--
Arnaud  Le Hors - Senior Technical Staff Member, Open Web Technologies - 
IBM Software Group


Holger Knublauch <holger@topquadrant.com> wrote on 03/18/2015 07:10:58 PM:

> From: Holger Knublauch <holger@topquadrant.com>
> To: RDF Data Shapes Working Group <public-data-shapes-wg@w3.org>
> Date: 03/18/2015 07:12 PM
> Subject: Anyone in support of SPARQL ASK constraints?
> 
> In an attempt to simplify the SHACL spec for users and implementers, I 
> would like to remove support for constraints based on SPARQL ASK. These 
> were supported in SPIN, because they are quick to write and produce a 
> boolean. However, they also caused issues in that many people did not 
> expect to return false to signal OK. The reason for that is that SELECT 
> and CONSTRUCT queries produce constraint violations, so the WHERE clause 

> should consistently return rows for the violating resources and values. 
> ASK can usually easily be replaced with SELECT * or SELECT (?this AS 
?root).
> 
> So is anyone currently in favor of keeping ASK in?
> 
>      http://w3c.github.io/data-shapes/shacl/#sparql-constraints-ask
> 
> If I don't hear back, I'll take them out of the draft on Monday.
> 
> Thanks
> Holger
> 
>