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Constructing containers and collections

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Fri, 10 Apr 2009 01:41:43 -0400
Message-ID: <49DEDC17.1010903@thefigtrees.net>
To: SPARQL Working Group <public-rdf-dawg@w3.org>
Leigh Dodds posted a suggested feature on our -comments list about 
providing a way to output dynamically sized RDF containers and 
collections in CONSTRUCT queries. The feature is summarized here:


I'll highlight Leigh's use case:

The primary example of where this was an issue was with working with a 
bibliographic dataset in which the Table of Contents for an issue of a 
journal or a book was modelled as an RDF List (i.e. as an ordered 
collection with a fixed membership). It was not possible to write 
CONSTRUCT queries to extract the information required to present a user 
interface showing all the desired data. The work around was to use a 
CONSTRUCT with ARQ list extensions to get the core data, a SELECT query 
and custom code to reconstitute the structure of the original list, and 
then a merge of the data graphs. Support for list construction in the 
query language would avoid the need for the extra code and queries.

There are no current SPARQL implementations that provide a mechanism 
that do this, to my knowledge. Does anyone on the list know differently?

As best I can tell, this feature stands on its own - no other 
combination of features that we are considering would enable this. 
(Assignment does not enable this since there is no "container" (or 
"collection") data type in SPARQL, and no way to emit such a 
hypothetical type within a CONSTRUCT template.

My gut feeling is that this is indeed a 'hole' in SPARQL, but the lack 
of existing implementations and the relative lack of demand that I've 
seen for this feature make me feel less inclined for the WG to pursue 

Does anyone on the group want to advocate for this feature?

Received on Friday, 10 April 2009 05:42:52 UTC

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