Content negotiation - Wikidata-tech

27 Aug 2015

Hi,

I am doing some 'kicking the tyres' tests on Wikidata as Linked Data.  I 
like the SPARQL end-point, which is more helpful than most, and 
successfully managed a query for "people with the surname Light" last 
night.  (Only five of them in the world, apparently, but that's another 
matter. :-) )

What I do have an issue with is the content negotiation.  I kept failing 
to get an RDF rendition of my results, and as a last resort I read the 
documentation [1].

This described a postfix pattern which delivers RDF XML (e.g. [2]). 
However, this pattern is itself subject to content negotiation, and an 
initial 303 response converts the URL to e.g. [3].  I am interested in 
knowing what pattern of URL will deliver RDF/XML /without /requiring 
content negotiation, and the answer to that question is not [2] but 
[3].  This matters, for example, in scenarios where one wants to use 
XSLT's document() function to retrieve an RDF XML response directly.  
The URL pattern [2] will fail.  So the documentation is currently unhelpful.

In a similar vein, is there a syntax for running a SPARQL query on 
Wikidata such that the response is delivered as RDF XML?  In many 
end-points there is a parameter you can add to specify the response 
format, which allows you to submit searches as HTTP requests and include 
the results directly in your (in my case XML-based) processing chain.  
An HTML results page isn't very machine-processible!

Thanks,

Richard

[1] https://www.wikidata.org/wiki/Wikidata:Data_access
[2] https://www.wikidata.org/entity/Q3807415.rdf
[3] https://www.wikidata.org/wiki/Special:EntityData/Q3807415.rdf

-- 
*Richard Light*