Projects/Nepomuk/SparqlQueries - Revision history

AnneW: Marked this version for translation

2012-12-12T13:47:19Z

Marked this version for translation

AnneW: Add ToC

2012-12-12T13:46:54Z

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AnneW: Prepare for translation

2012-12-12T13:42:07Z

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Vishesh: /* Sparql Prefixes */

2012-08-24T08:30:33Z

‎Sparql Prefixes

Vishesh: /* Running Sparql Queries */

2012-08-24T08:29:50Z

‎Running Sparql Queries

Vishesh at 08:29, 24 August 2012

2012-08-24T08:29:26Z

Vishesh: /* Sparql Prefixes */

2012-08-24T08:25:25Z

‎Sparql Prefixes

Vishesh: Created page with "Depending on the needs of your application you may need to directly run sparql queries. == Sparql Prefixes == When writing SPARQL queries, according to the standard one needs..."

2012-08-24T08:25:08Z

Created page with "Depending on the needs of your application you may need to directly run sparql queries. == Sparql Prefixes == When writing SPARQL queries, according to the standard one needs..."

New page

Depending on the needs of your application you may need to directly run sparql queries.

== Sparql Prefixes ==
When writing SPARQL queries, according to the standard one needs to prepend the queries with the prefixes that have been used. For example -
<syntaxhighlight lang="text">
PREFIX nco: <http://www.semanticdesktop.org/ontologies/2007/03/22/nco#> .
select ?r ?name where { ?r a nco:Contact . ?r nco:fullname ?name . }
</syntaxhighlight>

When running queries in Nepomuk, you do not need to explicitly add the prefix. The prefix will automatically be added by the storage service.

== Full Text Indexing ==
Nepomuk depends on [http://soprano.sourceforge.net/apidox/trunk/soprano_backend_virtuoso.html Virtuoso] for data storage. Virtuoso brings a lot of nice [http://docs.openlinksw.com/virtuoso/rdfsparql.html#sparqlextensions extensions to SPARQL]. Most importantly the full text search which is used through the artificial ''bif:contains'' property.

This allows to combine graph queries with full text queries in a nice way:

<syntaxhighlight lang="text">
select ?r where { ?r nao:prefLabel ?label .
?label bif:contains 'nepomuk' . }
</syntaxhighlight>

The query above will find any resources that contain ''nepomuk'' in their label.

Of course wildcards are supported, too. However, be aware that when using wildcards the expression itself needs to be enclosed in quotes as follows:

<syntaxhighlight lang="text">
select ?r where { ?r nao:prefLabel ?label .
?label bif:contains "'nepomuk*'" . }
</syntaxhighlight>

Please note the virtuoso '''requires a minimum of 4 leading characters''' in order to use wildcards.

@@ Line 3: / Line 3: @@
 __TOC__
-== Running Sparql Queries ==
+== Running Sparql Queries == <!--T:1-->
 Depending on the needs of your application you may need to directly run sparql queries.
 '''Nepomuk''' uses one main [http://soprano.sourceforge.net/apidox/stable/classSoprano_1_1Model.html Soprano model] which is accessed through the [http://api.kde.org/4.x-api/kdelibs-apidocs/nepomuk-core/html/classNepomuk_1_1ResourceManager.html ResourceManager]:
 <syntaxhighlight lang="cpp-qt">
      Soprano::Model* model = Nepomuk::ResourceManager::instance()->mainModel();
@@ Line 14: / Line 17: @@
 The queries can be run via this model -
 <syntaxhighlight lang="cpp-qt">
@@ Line 20: / Line 24: @@
      Soprano::QueryResultIterator it = model->executeQuery( query, Soprano::Query::QueryLanguageSparql );
-     while( it.next() ) {
+     <!--T:6-->
          kDebug() << it["r"].uri();
+     }
@@ Line 26: / Line 31: @@
-=== Sparql Prefixes ===
+=== Sparql Prefixes === <!--T:7-->
 When writing SPARQL queries, according to the standard one needs to prepend the queries with the prefixes that have been used. For example -
 <syntaxhighlight lang="text">
@@ Line 34: / Line 40: @@
 </syntaxhighlight>
 When running queries in Nepomuk, you do not need to explicitly add the prefix. The prefix will automatically be added by the storage service. In the future we will try to make virtuoso automatically understand all prefixes.
-=== Full Text Indexing ===
+=== Full Text Indexing === <!--T:10-->
 '''Nepomuk''' depends on [http://soprano.sourceforge.net/apidox/trunk/soprano_backend_virtuoso.html Virtuoso] for data storage. '''Virtuoso''' brings a lot of nice [http://docs.openlinksw.com/virtuoso/rdfsparql.html#sparqlextensions extensions to SPARQL]. Most importantly the full text search which is used through the artificial ''bif:contains'' property.
 This allows to combine graph queries with full text queries in a nice way:
 <syntaxhighlight lang="text">
 select ?r where { ?r nao:prefLabel ?label .
@@ Line 47: / Line 57: @@
 </syntaxhighlight>
 The query above will find any resources that contain ''nepomuk'' in their label.
 Of course wildcards are supported, too. However, be aware that when using wildcards the expression itself needs to be enclosed in quotes as follows:
 <syntaxhighlight lang="text">
 select ?r where { ?r nao:prefLabel ?label .
@@ Line 56: / Line 69: @@
 </syntaxhighlight>
 Please note the virtuoso '''requires a minimum of 4 leading characters''' in order to use wildcards.
 [[Category:Documentation]]
 [[Category:Development]]
 [[Category:Tutorials]]
 </translate>

← Older revision		Revision as of 13:46, 12 December 2012
Line 2:		Line 2:
	<translate>		<translate>

		+	__TOC__
	== Running Sparql Queries ==		== Running Sparql Queries ==

← Older revision		Revision as of 08:30, 24 August 2012
Line 29:		Line 29:


−	When running queries in Nepomuk, you do not need to explicitly add the prefix. The prefix will automatically be added by the storage service.	+	When running queries in Nepomuk, you do not need to explicitly add the prefix. The prefix will automatically be added by the storage service. In the future we will try to make virtuoso automatically understand all prefixes.

	== Full Text Indexing ==		== Full Text Indexing ==

@@ Line 5: / Line 5: @@
 <syntaxhighlight lang="cpp-qt">
-Soprano::Model* model = Nepomuk::ResourceManager::instance()->mainModel();
+    Soprano::Model* model = Nepomuk::ResourceManager::instance()->mainModel();
 </syntaxhighlight>
 The queries can be run via this model -

← Older revision		Revision as of 08:29, 24 August 2012
Line 1:		Line 1:
	Depending on the needs of your application you may need to directly run sparql queries.		Depending on the needs of your application you may need to directly run sparql queries.
		+
		+	= Running Sparql Queries =
		+	Nepomuk uses one main [http://soprano.sourceforge.net/apidox/stable/classSoprano_1_1Model.html Soprano model] which is accessed through the [http://api.kde.org/4.x-api/kdelibs-apidocs/nepomuk-core/html/classNepomuk_1_1ResourceManager.html ResourceManager]:
		+
		+	<syntaxhighlight lang="cpp-qt">
		+	Soprano::Model* model = Nepomuk::ResourceManager::instance()->mainModel();
		+	</syntaxhighlight>
		+
		+	The queries can be run via this model -
		+	<syntaxhighlight lang="cpp-qt">
		+	QString query = QString::fromLatin1("select ?r where { ?r a nco:Contact . }");
		+	Soprano::Model* model = Nepomuk2::ResourceManager::instance()->mainModel();
		+	Soprano::QueryResultIterator it = model->executeQuery( query, Soprano::Query::QueryLanguageSparql );
		+
		+	while( it.next() ) {
		+	kDebug() << it["r"].uri();
		+	}
		+	</syntaxhighlight>
		+

	== Sparql Prefixes ==		== Sparql Prefixes ==