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Questions tagged [arq]

A query engine for Jena that supports the SPARQL RDF Query language

A query engine for Jena that supports the SPARQL RDF Query language.

Features

  • Standard SPARQL
  • Free text search via Lucene
  • SPARQL/Update
  • Access and extension of the SPARQL algebra
  • Support for custom filter functions
  • Property functions for custom processing of semantic relationships
  • Aggregation, GROUP BY and assignment as SPARQL extensions
  • Support for federated query
  • Support for extension to other storage systems
  • Client-support for remote access to any SPARQL endpoint

Documentation

74 questions
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Is there a way to create several indexes in LARQ and execute SPARQL on them

I want to index two different OntModel and execute sparql queries on them. For example: String query = "PREFIX fise: \n" + "PREFIX pf: \n" …
suat
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Is there a way to rewrite INSERT, MODIFY or DELETE sparql using ARQ Jena Algebra?

I found some SPARQL query manipulation only for SELECT, ASK, CONSTRUCT https://jena.apache.org/documentation/query/manipulating_sparql_using_arq.html and https://jena.apache.org/documentation/query/algebra.html but could not find anything regarding…
Guillermo Coscarelli
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Jena ARQ adding update request element

I am working on an extension in Jena, where I have to add new Update element similar to UpdateModify but the logic is different and I do not want to extend UpdateModify. The UpdateVisitor interface does not have a visit method for the new element.…
Adrika
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How to return specific variable from SPARQL Federated Query (Service keyword)?

I'm using a federated query to retrieve some infos from a remote server, but I don't want to retrieve all the variables (select *) that I'm working on inside the federated query, I want to return just the count variable. How can I do…
Gabriel Gusmao
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Apache jena ARQ FILTER optimization

I have a reasonable implementation of Jena over MongoDB by providing impls for Graph and DatasetGraph. SPARQL queries are converted into the appropriate query expressions in MongoDB and material, at least on triple-match-by-triple-match basis, is…
Buzz Moschetti
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Custom ARQ function not working with fuseki endpoint

I successfully implemented sparql queries using custom ARQ functions using the following (custom function code): public class LevenshteinFilter extends FunctionBase2 { public LevenshteinFilter() { super() ; } public NodeValue…
Marc Agate
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How to convert string to URL with arq/tarql?

I got a TSV file that I'm converting with tarql. Column prop has strings like dc:source, skos:broader etc. How can I convert these to the corresponding URLs? Assume I have all needed prefixes defined in the tarql query. I can do this statically eg…
Vladimir Alexiev
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how to change the Node of a TriplePath in Jena?

I want to change a node of a Jena TriplePath (org.apache.jena.sparql.core.TriplePath), but I haven't found any manner. Imagine I have this code: TriplePath tp = null; .... //tp has been defined and not null Node domain = tp.getSubject(); Node…
tremendows
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Updating Fuseki using dataSetAccessor

I have installed fuseki version 1.0.2 and I can successfully run it using --> ./fuseki-server --update --loc=/home/mytdbs/tdb /ds and query it on http://localhost:3030/sparql.tpl. I have a tdb and I want to update it using java. To do so I am…
Bahar
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Currently in a locked region: Fuseki + full text search + inference

I've recently started playing with the full text search in the Fuseki 0.2.8 snapshot. I have an InfModel backed by a TDB dataset, which I've added a Lucene text index to. I have tested it out with some search queries like this: prefix text:…
stu
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Jena SPARQL update doesn't execute

My situation is simple: I have an RDF (N3) file that I want to upload into sparql-auth-endpoint. I use Jena ARQ, but unfortunately it doesn't work; I get no errors, but the graph doesn't change. Where could be the problem? My code: HttpContext…
159753
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How to get Dbpedia resource details using Jena?

After I query dbpedia over its Sparql endpoint, I get results as Jena ResourceImpl objects. Then how I can get details of this resource? For example if this resource is a person; how can I get his/her birthDate? I tried this one; but it always…
talha06
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Jena/Sparql/Arq: injecting some statements in the model during the query

I have build a small RDF model: it only contains a few triples describing some items on the human genome. I want to retain only those items overlapping some genomic segments (say a "gene"), stored in another relational database. This database of…
Pierre
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One SPARQL endpoint for Select, Describe and Construct using Jena ARQ

I have built a simple webpage as the frontend user interface for users to enter the sparql query. I am using Jena ARQ as the backend (I am using Grails) sparql query engine. Currently, users can only enter a "Select" query and I use: ResultSet…
afterglowlee
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Jena UpdateFactory

I was wondering if it was possible to create a SPARQL UpdateRequest in Jena by using ARQ Op objects. I would be interested to create programmatically updates like this: DELETE {?s :predicate } INSERT {?s :predicate…
GCorrendo
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