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SPARQL Protocol question - details of 2.1.2 query In Message

From: Hookway, Ray <Ray.Hookway@hp.com>
Date: Fri, 13 Jul 2007 11:25:54 -0400
Message-ID: <0A10A2BCDD28FB44AFEC4E3FB034EE5301C587A9@tayexc14.americas.cpqcorp.net>
To: <public-rdf-dawg-comments@w3.org>
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
<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
<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
<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
<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.)
 
Please let me know if this is not clear.
 
Thanks.
 
-Ray Hookway
Hewlett-Packard
Received on Friday, 13 July 2007 21:23:37 GMT

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