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Add a standardized extension of SPARQL Query Results XML format #12

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abrokenjester opened this issue Oct 13, 2020 · 1 comment
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Add a standardized extension of SPARQL Query Results XML format #12

abrokenjester opened this issue Oct 13, 2020 · 1 comment
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@abrokenjester
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abrokenjester commented Oct 13, 2020 •
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The result of a SPARQL SELECT query is serialized in XML using the SPARQL Query Results XML format. This format will need to be extended to deal with the RDF* triple being a new possible value type for a binding. For example, the result of a query where variable ?a is bound to an RDF* triple:

?a ?b ?c
<<<http://example.org/bob> <http://xmlns.com/foaf/0.1/age> 23>> <http://example.org/certainty> 0.9

Currently, different implementations all have their own, slightly diverging, extensions. For example, in Eclipse RDF4J, the extension looks as follows:

<?xml version='1.0' encoding='UTF-8'?>
<sparql xmlns='http://www.w3.org/2005/sparql-results#'>
	<head>
		<variable name='a'/>
		<variable name='b'/>
		<variable name='c'/>
	</head>
	<results>
		<result>
			<binding name='a'>
				<triple>
					<subject>
						<uri>http://example.org/bob</uri>
					</subject>
					<predicate>
						<uri>http://xmlns.com/foaf/0.1/age</uri>
					</predicate>
					<object>
						<literal datatype='http://www.w3.org/2001/XMLSchema#integer'>23</literal>
					</object>
				</triple>
			</binding>
			<binding name='b'>
				<uri>http://example.org/certainty</uri>
			</binding>
			<binding name='c'>
				<literal datatype='http://www.w3.org/2001/XMLSchema#decimal'>0.9</literal>
			</binding>
		</result>
	</results>
</sparql>

In Apache Jena, the extension is almost identical, except for the choice to name the middle element property (where RDF4J uses predicate):

<?xml version='1.0' encoding='UTF-8'?>
<sparql xmlns='http://www.w3.org/2005/sparql-results#'>
	<head>
		<variable name='a'/>
		<variable name='b'/>
		<variable name='c'/>
	</head>
	<results>
		<result>
			<binding name='a'>
				<triple>
					<subject>
						<uri>http://example.org/bob</uri>
					</subject>
					<property>
						<uri>http://xmlns.com/foaf/0.1/age</uri>
					</property>
					<object>
						<literal datatype='http://www.w3.org/2001/XMLSchema#integer'>23</literal>
					</object>
				</triple>
			</binding>
			<binding name='b'>
				<uri>http://example.org/certainty</uri>
			</binding>
			<binding name='c'>
				<literal datatype='http://www.w3.org/2001/XMLSchema#decimal'>0.9</literal>
			</binding>
		</result>
	</results>
</sparql>

In Stardog, the implemented extension currently looks as follows:

<?xml version='1.0' encoding='UTF-8'?>
<sparql xmlns='http://www.w3.org/2005/sparql-results#'>
	<head>
		<variable name='a'/>
		<variable name='b'/>
		<variable name='c'/>
	</head>
	<results>
		<result>
			<binding name='a'>
				<statement>
					<s>
						<uri>http://example.org/bob</uri>
					</s>
					<p>
						<uri>http://xmlns.com/foaf/0.1/age</uri>
					</p>
					<o>
						<literal datatype='http://www.w3.org/2001/XMLSchema#integer'>23</literal>
					</o>
				</statement>
			</binding>
			<binding name='b'>
				<uri>http://example.org/certainty</uri>
			</binding>
			<binding name='c'>
				<literal datatype='http://www.w3.org/2001/XMLSchema#decimal'>0.9</literal>
			</binding>
		</result>
	</results>
</sparql>

In summary, RDF4J, Jena and Stardog all differ in the element names used (triple vs statement, property vs predicate, subject vs s, etc).

Other implementations may have yet other, slightly deviant variants. This makes it difficult to process query results from different endpoint implementations. A single recommended extension would be a benefit for parser implementors and users alike.
@abrokenjester abrokenjester mentioned this issue Oct 13, 2020
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@pchampin pchampin added sparql-star About SPARQL-star help wanted Extra attention is needed labels Nov 10, 2020
abrokenjester added a commit to metaphacts/rdf-star that referenced this issue Nov 19, 2020
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w3cGH-12 w3cGH-13 basic specification of XML and JSON result formats
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abrokenjester added a commit to metaphacts/rdf-star that referenced this issue Nov 20, 2020
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w3cGH-12 w3cGH-13 added introduction paragraph
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abrokenjester added a commit to metaphacts/rdf-star that referenced this issue Nov 20, 2020
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w3cGH-12 w3cGH-13 basic specification of XML and JSON result formats
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abrokenjester added a commit to metaphacts/rdf-star that referenced this issue Nov 21, 2020
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w3cGH-12 w3cGH-13 adjust citation
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@hartig hartig mentioned this issue Nov 27, 2020
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pchampin pushed a commit that referenced this issue Dec 11, 2020
@abrokenjester @pchampin
GH-12 GH-13 basic specification of XML and JSON result formats
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pchampin pushed a commit that referenced this issue Dec 11, 2020
@abrokenjester @pchampin
GH-12 GH-13 adjust citation
ba867fe
@pchampin
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This was solved a while ago by #39

@pchampin pchampin removed the help wanted Extra attention is needed label Jan 14, 2021
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