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Re: SPIN prospects

From: David Booth <david@dbooth.org>
Date: Wed, 30 Jan 2013 11:30:10 -0500
To: Graham Klyne <GK@ninebynine.org>
Cc: Dave Reynolds <dave.e.reynolds@gmail.com>, semantic-web@w3.org
Message-ID: <1359563410.25867.1937.camel@dbooth-laptop>
On Wed, 2013-01-30 at 12:29 +0000, Graham Klyne wrote:
> On 30/01/2013 08:47, Dave Reynolds wrote:
> > Personally I make heavy use of SPARQL as it is, including templating (both
> > syntactic and injecting bindings into a query execution), quite happily without
> > the need for SPIN. When I store SPARQL queries embedded in RDF I find a simpler
> > embedding works just fine.
> FWIW, I do similarly, and haven't felt drawn to using SPIN.

Likewise.  I routinely use SPARQL as a simple rules language, and
although I think the general approach of SPIN is excellent, I use native
SPARQL instead for a few reasons:

 - I'm slightly skeptical about the special use of the "?this" variable
in SPIN.

 - I don't care for the SPIN serialization into RDF that shreds the
query into tiny pieces, making it even harder to read than RDF's awful
"reification".  I understand why TopQuadrant did it that way, as it
facilitates operations like changing namespace prefixes.  But for what I
do, I prefer to treat a SPARQL template as a simple string with
syntactic placeholders:

 - I prefer to use SPARQL INSERT instead of CONSTRUCT for inference
rules, so that the result of the rule goes directly into a (usually
temporary) new named graph, rather than being returned to the client.  I
find this style of putting inferences into a temporary named graph helps
in debugging, as you can easily see exactly what triples you got.  

I've done a lot of SPARQL scripts of the following form:

# For maintainability I define prefixes for my graph names:
PREFIX tempGraph: < ... > 
PREFIX sourceGraph: < ... >
PREFIX destinationGraph: < ... >


INSERT { GRAPH tempGraph: { ... } }     # Rule consequents
WHERE { GRAPH sourceGraph: { ... } } ;  # Rule antecedents

# Comment out the following lines until the rule is debugged:
ADD GRAPH tempGraph: TO GRAPH destinationGraph: ;

Another benefit of this kind of SPARQL script is that you can DELETE
triples also, if needed.

David Booth, Ph.D.

Aaron's Law, in memory of Web prodigy and open information 
advocate Aaron Swartz: http://bit.ly/USR4rx 

Opinions expressed herein are my own and do not necessarily 
reflect those of my employer.
Received on Wednesday, 30 January 2013 16:30:40 UTC

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