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Re: Property groups and Combinations

From: Holger Knublauch <holger@topquadrant.com>
Date: Sat, 24 Jan 2015 21:19:56 +1000
Message-ID: <54C37FDC.7070601@topquadrant.com>
To: RDF Data Shapes Working Group <public-data-shapes-wg@w3.org>

On 1/24/15, 8:36 PM, Jose Emilio Labra Gayo wrote:
>
> And how would you combine it with closed shapes? Should you add 
> another SPARQL query negating all the definition?

Closed shapes are one very specific scenario, and whether they are 
important enough is yet for the WG to decide. If they are as rare as I 
believe they are, then the hack with SPARQL is sufficient IMHO. If they 
are more common, then we can add a feature to LDOM to make them more 
convenient. No problem.

>
> Anyway, it is nice to see that the LDOM is going in a direction that 
> is very close to ShEx...once you separate shapes from classes and add 
> recursive shapes, ShEx with semantic actions represented in SPARQL 
> seems almost the same as LDOM, isn't it? What I am missing now is why 
> should we need a different technology if we could use and improve ShEx...

Jose, I am trying very hard to come up with a design that is a 
compromise that we all feel at home with. I could make exactly the same 
statements about SPIN. Of course there can be multiple starting points, 
as long as we merge the best ideas together. But ShEx is a largely 
untested language with a very short history, mostly in academia. SPIN 
has been around for 7 years or so, and has passed the test of time in 
large industry projects, no matter how many times you repeat your 
personal preference to separate classes and shapes.

The fact that the whole ShEx community is present on this WG does not 
mean that ShEx has wide support or will be a popular technology.

We are producing a new technology, with a new name, which includes 
lessons learned from multiple input technologies.

>
> Maybe, the other missing feature would be the addition of semantic 
> actions, which could interact with the validation process in a lot of 
> interesting ways. If the semantic actions contain SPARQL queries, 
> then, they look similar to LDOM, but allowing the semantic actions to 
> contain other kinds of languages would provide future extensibility of 
> the language, which would allow some nice applications like the 
> examples provided in Eric's demos.

I have intentionally chosen the name ldom:sparql to link to SPARQL 
query, because I expect future versions to have something like 
ldom:javascript. In fact TopBraid has included a SPIN extension for 
JavaScript-based functions since 2009 [1] and it's a useful thing to 
have if you are OK with increasing the cost of adoption.

Holger

[1] 
http://composing-the-semantic-web.blogspot.com.au/2009/03/using-javascript-to-define-sparql.html
Received on Saturday, 24 January 2015 11:20:28 UTC

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