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Re: SPARQL Protocol question - details of 2.1.2 query In Message

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Tue, 28 Aug 2007 09:48:10 -0400
Message-ID: <46D4279A.80202@thefigtrees.net>
To: "Hookway, Ray" <Ray.Hookway@hp.com>
CC: public-rdf-dawg-comments@w3.org

Hookway, Ray wrote:
> I found what I  believe to be a problem in the SPARQL protocol 
> specification. The basic problem is a disparity between 
> http://www.w3.org/2005/09/sparql-protocol-types which is imported by 
> http://www.w3.org/TR/rdf-sparql-protocol/sparql-protocol-query.wsdl and 
> http://www.w3.org/TR/rdf-sparql-protocol/sparql-protocol-types.xsd. The 
> later two are both referenced in the spec and 
> http://www.w3.org/TR/rdf-sparql-protocol/sparql-protocol-types.xsd is 
> quoted in the spec. The version of sparql-protocol-types which is 
> referenced by the wsdl document describes the type of a query-request as 
> <xs:all>. The other version describes the type of a query-request as an 
> <xs:sequence>. The former allows query, default-graph-uris and 
> named-graph-uris in any order. However, it contains what looks like an 
> error in declaring a maxOccurs of "unbounded" for default-graphs-uri and 
> named-graph-uri. MaxOccurs can only be 0 or 1 for elements of <xs:all>. 
> The intent seems to be to allow multiple default-graph-uris and 
> named-graph-uris, but this isn't allowed by XMLSchema. It looks to me 
> like you're caught in a bind here. <xs:sequence> requires a fixed order, 
> but allows unbounded occurrences. <xs:all> allows arbitrary order, but 
> requires at most one occurrence. (All this has to do with the XML 
> description of the message. I'm not sure how this gets mapped by the 
> HTML binding - i.e., the binding may allow a rearrangement of the 
> elements although I doubt it.)

Hi Ray,

Thanks for bringing this to our attention and my apologies on the delay 
in responding.

The versions referenced by the spec. are the correct versions, and the 
dated version imported by the wsdl file is an old, incorrect version.

I will investigate what needs to be done to fix this problem.

Lee

PS The serialization rules in 
http://www.w3.org/TR/wsdl20-adjuncts/#_http_operation_location_query_constr 
seem to indicate that the parameters must be serialized in the order of 
the elements in the XML document, as you speculated. In the case of the 
SPARQL protocol, this means query first, then default-graph-uri, then 
named-graph-uri.
>  
> Please let me know if this is not clear.
>  
> Thanks.
>  
> -Ray Hookway
> Hewlett-Packard
Received on Tuesday, 28 August 2007 13:48:24 GMT

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