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Questions tagged [r2rml]

R2RML is a language for expressing customized mappings from relational databases to RDF datasets.

R2RML is a language for expressing customized mappings from relational databases to RDF datasets.

An R2RML mapping refers to logical tables to retrieve data from the input database. A logical table can be one of the following:

  • A base table,
  • a view, or
  • a valid SQL query (called an “R2RML view” because it emulates a SQL view without modifying the database).

Each logical table is mapped to RDF using a triples map. The triples map is a rule that maps each row in the logical table to a number of RDF triples.

The rule has two main parts:

  1. A subject map that generates the subject of all RDF triples that will be generated from a logical table row. The subjects often are IRIs that are generated from the primary key column(s) of the table.
  2. Multiple predicate-object maps that in turn consist of predicate maps and object maps (or referencing object maps).

Triples are produced by combining the subject map with a predicate map and object map, and applying these three to each logical table row.

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Is there a Java open source implementation of R2RML?

I want to generate RDF data from tabular data, in particular: CSV, TSV, spreadsheets (either Excel or OpenOffice) and, eventually, tables in RDBMS. I am aware of the "RDB to RDF Mapping Language" (R2RML) (http://www.w3.org/TR/r2rml/) current…
castagna
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Difference between Direct Mapping and R2RML

I've tried to figure out what's differences between the two rdb2rdf mapping languages Direct Mapping and R2RML are. I understand that booth languages generate RDF files that stand for a virtual RDF graph - which can be accessed via SPARQL. So…
Kody
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How do I iterate over a SPARQL query referring to a virtual graph?

I am developing a Virtuoso stored procedure. I want to perform a loop over the result of a SPARQL query to a graph. The problem comes when the query contains a reference to a virtual graph (a graph not physically in the triplestore, being the…
Bepi
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Expose RDBMS (SQLite) data as SPARQL endpoint

I am working on a demo for which I need to expose some data stored in the SQLite DB file as a SPARQL endpoint that can be queried. This doesn't have to be fancy at the moment just a way to expose static data as the RDF is fine for me. I am wondering…
Kiran
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R2RML Blank Node within rr:objectMap

I was wondering how I could model the following with r2rml: Person -> has an address --> Blank Node [ Street Name, Postal Code, City ] I'm note sure how I can add street name, postal code and city to the blank node within the…
Kody
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Common R2RML mapping file for all the tables

I am working on a project to help the user manually import their data sources in the format of CSV or JSON, then the data will be imported into the data warehouse, after that these data sources will be automate generate to RDF Data cubes with R2RML…
Rio Vo
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How to import/read an owl ontology created by protege in Jena

I created an owl ontology in Protege (ontologyEx.owl). I also have rdf triples created by r2rml engine (file name is example.ttl). Is it possible to import/read ontologyEx.owl in Jena and do reasoning with my model that reads rdf triples (i.e. Model…
Massi
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Ontop can not Import mappings

I am trying to make this tutorial http://optique-project.eu/training-programme/module-ontop/ In this step Import mappings: Ontop>>Import R2RML mappings… I am waiting more than a hour and no result. This is what it…
Seb
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Is there any way in rml / r2rml to take a value as an IRI?

I'm using RMLMapper to transfrom JSON to RDF. One of the values stored in the JSON is a URL. I would like to use this as the basis of an IRI for the object of RDF statements. The input is { "documentId": { "value": "http://example.org/345299" …
Phil Barker
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What are the pros and cons of RDB2RDF tools?

I need to know the difference between RDB2RDF tools. Could anybody tell me what are the pros and cons of RDB2RDF tools? Especially for the following ones: Virtuoso, Ultrawrap, Ontop, Morph, Xsparql, D2RQ,....
rawan az
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R2RML mapping with values from another table

I want to use R2RML and Virtuoso to map some tables from a MySql source. I have a table with "Things" and I want them to have predicates that are not URIs but coming from the name column from a table "Values" connected via the thingID. I can map…
user1722267
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Dynamic Predicate in R2RML

I need to make a mapping that involve one simple table, however my predicate needs to be dynamic based on the values coming from one column. This is my query: SELECT item_id, Concat_WS('@', metadatavalue.text_value,…
MaatDeamon
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Java for converting DAO to R2RML for RDF creation?

Does anyone know of any programming techniques for converting a Java DAO objects(i.e. objects created from a database schema) to R2RML objects/files for RDF creation in graph databases*? I am working with a non-standard database, and only have the…
Fuzzy Analysis
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Conditional creation of property in R2RML

I'm playing around with R2RML and I was wondering if I can create a property depending on the content of a RDB table cell. The D2RQ mapping language has d2rq:condition that can handle that. e.g.: if value in column/table cell 'name' is 'abc' create…
Kody
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Is R2RML suitable for EAV tables?

Beginning to read about R2RML I wonder if this language would also be suitable for mapping database tables that follow the entity-attribute-value model to RDF and how a simple example would look like. A survey of RDB to RDF translation approaches…
Jens Piegsa
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