Re: Role of SPARQL

On 11/26/2014 15:58, Eric Prud'hommeaux wrote:
> I'm happy to be pragmatic; let's look at the cost of all of these
> approaches.
> If we want to define Resource Shapes, remember that it is a recursive
> language (the valueShape of a Resource Shape is in turn another
> Resource Shape). There is no way to express that in SPARQL without
> hand-waving "and then you call the function again here" or "and then
> you embed this operation here" text.

The "hand-waving" here is that a compliant SPARQL engine needs to 
implement a SPARQL function such as

      shape:hasShape(?resource, ?shape) : xsd:boolean

which would be part of the spec that this WG produces.

However this is "just another SPARQL function" and doesn't require any 
further changes to the language. Most SPARQL engines already have 
functions that go beyond the official SPARQL 1.1 spec. The cost of that 
sounds manageable to me.

SPIN also has the extension mechanism for user-defined functions, which 
is for example already implemented by AllegroGraph. With a W3C logo on 
it, I am confident that most interested database vendors would do the same.

Of course no RDF database would have native support for Shapes at this 
stage yet, so of course something needs to be implemented.


Received on Wednesday, 26 November 2014 06:13:34 UTC