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Ambiguity between SPARQL 1.1 RDF protocol query via GET and SD retrieval

From: Chime Ogbuji <chimezie@gmail.com>
Date: Sat, 6 Oct 2012 16:07:16 -0400
To: SPARQL Group <public-rdf-dawg@w3.org>
Message-ID: <CA7F0D851ED1486A9DDC853080D06E0D@gmail.com>
While porting over my implementation of the SPARQL 1.1 RDF protocol, I noticed that the language in the Service Description specification about how a service description document is dereferenced is a bit ambiguous.

"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" 

Whereas the SPARQL 1.1 RDF Protocol document says:

"Protocol clients may send protocol requests via the HTTP GET method. When using the GET method, clients must URL percent encode (http://www.ietf.org/rfc/rfc3986.txt) all parameters and include them as query parameter (http://www.ietf.org/rfc/rfc3986.txt) strings with the names given above"

Under the query string parameters column for this binding it says: "query (exactly 1)". 

Unless I've missed text elsewhere that clarifies this, reading both as they are written begs the question about whether a query via GET binding request SHOULD return an SD document. My assumption is that the distinction is between a GET request to the service endpoint *without* a query parameter versus a request *with* this parameter - returning an SD document if the query parameter is not provided.

This distinction should be made explicit. Some suggested text (in SD specification):

"[...] should return a service description document at the service endpoint when dereferenced using the HTTP GET operation without any query parameter strings provided"

-- 
Chime Ogbuji
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Received on Saturday, 6 October 2012 20:07:48 GMT

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