W3C home > Mailing lists > Public > public-rdf-dawg-comments@w3.org > December 2012

Re: Default serialisation for SPARQL Service Description

From: Paul Gearon <gearon@ieee.org>
Date: Mon, 10 Dec 2012 16:25:30 -0500
Message-ID: <CAGZNPFmiZkcv1iC0SHk=NTAe1k8xgyDFmiZxhEFPBxykKgWOqg@mail.gmail.com>
To: Leigh Dodds <leigh@ldodds.com>
Cc: public-rdf-dawg-comments <public-rdf-dawg-comments@w3.org>
Hi Leigh,

Disclaimer: I'm writing this personally without having spoken with anyone
at all, so nothing I say should be considered to represent the working
group at all.

On Fri, Dec 7, 2012 at 11:12 AM, Leigh Dodds <leigh@ldodds.com> wrote:

> Hi,
> Section 2 of the SPARQL Service Description Document [1] says:
> "SPARQL services made available via the SPARQL Protocol should return
> a service description document at the service endpoint when
> dereferenced using the HTTP GET operation without any query parameter
> strings provided. This service description must be made available in
> an RDF serialization, may be embedded in (X)HTML by way of RDFa
> [RDFA], and should use content negotiation [CONNEG] if available in
> other RDF representations."
> However it doesn't recommend a *default* serialization for the
> description.

I can't recall if this was discussed, but in general if something isn't
explicitly specified then it is to provide maximum flexibility for

> An RDF serialization MUST be provided and several may be
> provided via content negotiation, but if a service is only going to
> support a single format, the specification doesn't recommend one.
> Presumanbly the intention is that RDF/XML should be the default
> although with Turtle being standardised an implementor might
> reasonably choose that instead.

This is what prompted my response.

Yes, RDF/XML is the only formally ratified standard for the moment.
However, I believe that the majority prefer Turtle, and in many systems
RDF/XML is outright deprecated. (I'm actively ignoring it some some new
projects). So when you say that the intention is "presumably" RDF/XML I
would suggest that it isn't. Indeed the tension between formal standards
(RDF/XML) vs. something useful (Turtle) could well be the motivation for

> In practice I assume that most services will probably support multiple
> serializations, but I think having a recommended default would be
> useful.

I agree that most systems will probably support more than one. After all,
it's no big deal to use a Jena lib for the common representations, and
anyone wanting to implement less common formats (e.g. TriG) would probably
want to support a more common format as well.

The WG winds up soon, but there should be an opportunity to respond before

Paul Gearon
Received on Monday, 10 December 2012 21:26:05 UTC

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