W3C home > Mailing lists > Public > public-lod@w3.org > February 2013

Re: Content negotiation for Turtle files

From: Leigh Dodds <leigh@ldodds.com>
Date: Wed, 6 Feb 2013 11:38:23 +0000
Message-ID: <CAC_nr_rZc_O5E-c11TShsc-1BFA6h4hW8XJaA9pzUDF_ehrFcQ@mail.gmail.com>
To: Bernard Vatant <bernard.vatant@mondeca.com>
Cc: public-lod@w3.org
Hi,

On Wed, Feb 6, 2013 at 9:54 AM, Bernard Vatant
<bernard.vatant@mondeca.com> wrote:
> ...
> But what I still don't understand is the answer of Vapour when requesting
> RDF/XML :
>
> 1st request while dereferencing resource URI without specifying the desired
> content type (HTTP response code should be 303 (redirect)): Passed
> 2nd request while dereferencing resource URI without specifying the desired
> content type (Content type should be 'application/rdf+xml'): Failed
> 2nd request while dereferencing resource URI without specifying the desired
> content type (HTTP response code should be 200): Passed

>From a purely HTTP and Content Negotiation point of view, if a client
doesn't specify an Accept header then its perfectly legitimate for a
server to return a default format of its choosing. I think it could
also decide to serve a 300 status code and prompt the client to choose
an option thats available.

>From an interoperability point of view, having a default format that
clients can rely on is reasonable. Until now, RDF/XML has been the
standardised format that we can all rely on, although shortly we may
all collectively decide to prefer Turtle. So ensuring that RDF/XML is
available seems like a reasonable thing for a validator to try and
test for.

But there's several ways that test could have been carried out. E.g.
Vapour could have checked that there was a RDF/XML version and
provided you with some reasons why that would be useful. Perhaps as a
warning, rather than a fail.

The explicit check for RDF/XML being available AND being the default
preference of the server is raising the bar slightly, but its still
trying to aim for interop.

Personally I think I'd implement this kind of check as "ensure there
is at least one valid RDF serialisation available, either RDF/XML or
Turtle". I wouldn't force a default on a server, particularly as we
know that many clients can consume multiple formats.

This is where automated validation tools have to tread carefully:
while they play an excellent role in encouraging consistently, the
tests they perform and the feedback they give need to have some
nuance.

Cheers,

L.

-- 
Leigh Dodds
Freelance Technologist
Open Data, Linked Data Geek
t: @ldodds
w: ldodds.com
e: leigh@ldodds.com
Received on Wednesday, 6 February 2013 11:38:51 UTC

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