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Questions about SPARQL 1.1 service description

From: Nicholas Humfrey <nicholas.humfrey@bbc.co.uk>
Date: Tue, 22 Feb 2011 09:56:25 +0000
To: SPARQL Working Group <public-rdf-dawg@w3.org>
CC: Gregory Williams <greg@evilfunhouse.com>
Message-ID: <C98938C9.366D2%nicholas.humfrey@bbc.co.uk>

I have been starting to update my service description code in RedStore to be
compatible with SPARQL 1.1 Service Description. It has brought up a few
questions. My questions are based on version 1.49 of the document.

1) There is currently very little mention of the SPARQL 1.1 RDF Dataset HTTP
Protocol. Is this a separate sd:Service, with a separate service
description? How is the service type indicated in the service description?

2) RedStore supports multiple query languages: sparql10, sparql11, laqrs and
rdql. This is currently set using a lang= argument. Should there be one
endpoint per query language? Should each endpoint have its own service
description? How do you discover which endpoints are available?

3) What URI do I use for the description of non-RDF based result formats?
Examples include HTML Tables, Atom, RSS, the GraphViz DOT format, CSV, TSV
etc. Should I create my own, should they be bNodes in the service
description or should they be in a more generic location?

4) In section 5, Conformance, it states that service descriptions MUST
include a <service-URL> rdf:type sd:Service triple. However the example in
Section 4 doesn't include this triple (without inferencing).

5) There doesn't currently seem to be a way to distinguish between query
result formats (from an ASK or SELECT) and RDF serialisations (CONSTRUCT or
DESCRIBE). I think this would be a useful distinction, particularly if
trying to work out which formats are supported for a GET using the SPARQL
1.1 RDF Dataset HTTP Protocol.

6) For clarity, perhaps the vocabulary that is used to describe formats (for
example http://www.w3.org/ns/formats/media_type) should be part for the
service description vocabulary, particularly if format descriptions are
inlined within the service description.

7) Redland/RedStore are unlikely to support Property Paths in the near
future, is there are way to describe this?

8) Has anyone implemented SPARQL 1.1 service description yet? Are there any
real world examples?


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Received on Tuesday, 22 February 2011 09:56:59 UTC

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