Re: SPIN prospects

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: < ... >

CLEAR SILENT GRAPH tempGraph: ;

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: ;
DROP SILENT GRAPH tempGraph: ;

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



-- 
David Booth, Ph.D.
http://dbooth.org/

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