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Re: ISSUE-105: Possible compromise

From: markh <markh@metarelate.net>
Date: Thu, 8 Sep 2016 19:13:28 +0000
Cc: "public-data-shapes-wg@w3.org" <public-data-shapes-wg@w3.org>
Message-ID: <20160908191328.174da5d6@eddy>
Following today's conversations, Ted's suggestions about
concatenation and strings or graphs I thought to follow up

If the 'prefixes' are defined in SPARQL syntax and the SPARQL query is
formed explicitly by string manipulation I think this may look
something like: 


ex:BasePrefixes
     a sh:PrefixDeclaration ;
     sh:sparqlPrologue
"
prefix rdfs: <http://w3c.nobody.can.remember.the.bloody.date>
" .

ex:MyPrefixes
     a sh:PrefixDeclaration ;
     sh:sparqlPrologue 
"
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
prefix owl:<http://www.w3.org/2002/07/owl#>
" .

ex:MyShape
     a sh:Shape ;
     sh:sparql [
         sh:prefixes ex:MyPrefixes ;
         sh:prefixes ex:BasePrefixes ;
         sh:select "SELECT * { $this rdfs:seeAlso ex:MyResource }" ;
     ] .


I wanted to write this down to see it and check my interpretation

Is this consistent with people's views of what was discussed?


cheers
mark


On Fri, 2 Sep 2016 06:30:34 +1000
Holger Knublauch <holger@topquadrant.com> wrote:

> Given that the majority of people in today's call were against having
> a simple sh:prefix property, I was asked to propose a variant that
> may be "just" acceptable to everyone. The idea of this proposal is
> that each node that defines a SPARQL query that wishes to reuse
> prefixes from elsewhere must explicitly point at those definitions.
> And the prefix declarations would live in a separate node that may
> extend the declarations from others.
> 
> Example:
> 
> ex:BasePrefixes
>      a sh:PrefixDeclaration ;
>      sh:declare [
>          sh:prefix "rdfs" ;
>          sh:namespace
> "http://w3c.nobody.can.remember.the.bloody.date" ; ] ;
>      sh:declare [
>          sh:prefix "sh" ;
>          ...
>      ] .
> 
> ex:MyPrefixes
>      a sh:PrefixDeclaration ;
>      sh:extends ex:BasePrefixes ;
>      sh:declare [
>          sh:prefix "ex" ;
>          sh:namespace "http://example.com/ns#" ;
>      ] .
> 
> ex:MyShape
>      a sh:Shape ;
>      sh:sparql [
>          sh:prefixes ex:MyPrefixes ;
>          sh:select "SELECT * { $this rdfs:seeAlso ex:MyResource }" ;
>      ] .
> 
> The mechanism would be that the system would prepend the SELECT with
> the prefixes defined in any sh:prefixes, including those that
> sh:extends. An error would be flagged if prefixes conflict. Some
> tools can (and will) of course produce the sh:PrefixDeclarations
> automatically, and inject the sh:prefixes declarations if desired. I
> guess some tools will make this optional and may just inject the
> SPARQL prefix declarations automatically.
> 
> A variation of this would be to have a standard set of prefixes that
> is always included by default, e.g. sh:DefaultPrefixes with rdf,
> rdfs, xsd, sh and owl prefixes. Clashes on those are extremely
> unlikely and many queries don't need any others, saving the
> sh:prefixes triple.
> 
> Discussion: this is obviously a more verbose mechanism, with a lot of 
> new properties. But it does IMHO address the main issues that were 
> raised and people who are hand-writing Turtle files with lots of
> SPARQL queries at least have a shorthand notation.
> 
> Regards,
> Holger
> 
> 
Received on Thursday, 8 September 2016 19:14:50 UTC

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