Stack Overflow
Stack Overflow

Questions tagged [d2rq]

The D2RQ Platform is a system for accessing relational databases as virtual, read-only RDF graphs. It offers RDF-based access to the content of relational databases without having to replicate it into an RDF store.

The D2RQ Platform is a system for accessing relational databases as virtual, read-only RDF graphs. It offers -based access to the content of relational databases without having to replicate it into an RDF store.

The main features of D2RQ are:

  • query a non-RDF database using SPARQL
  • access the content of the database as Linked Data over the Web
  • create custom dumps of the database in RDF formats for loading into an RDF store
  • access information in a non-RDF database using the Apache Jena API

The D2RQ Platform consists of:

  • The D2RQ Mapping Language a declarative mapping language for describing the relation between an ontology and an relational data model.
  • The D2RQ Engine a plug-in for the Jena Semantic Web toolkit, which uses the mappings to rewrite Jena API calls to SQL queries against the database and passes query results up to the higher layers of the frameworks.
  • D2R Server an HTTP server that provides a Linked Data view, a HTML view for debugging and a SPARQL Protocol endpoint over the database.

The currently supported databases are

You should be using this tag if your question is related to the use of D2RQ platform or its integration with other databases.

32 questions
3
votes
1 answer

D2RQ parameters for generate-mapping

We are currently working on a project involving an "ordinary" relational database, but we wish to enable SPARQL requests towards this database. d2rq.org is a tool that enables SPARQL to be run towards the database with the help of a .ttl file which…
K_scheduler
  • 101
  • 4
2
votes
1 answer

Add type triple to rdf document using D2RQ

If I use the default d2rq mapping file (ttl) all my colums are mapped to rdf properties. E.g. the colum ID becomes the Property "hasID" (after renaming).
user3579222
  • 1,103
  • 11
  • 28
2
votes
0 answers

D2R Server-Sparql Join with-generate-mapping DB MySQL

I have to do a join from this 2 tables, on the field ID_CLIENTI. These tables, on MySQL DB, are mapped with generate-mapping on D2R Server in a turtle file. Table CLIENTI map:CLIENTI a d2rq:ClassMap; d2rq:dataStorage map:database; d2rq:uriPattern…
Francesco Marchitelli
  • 137
  • 1
  • 11
1
vote
0 answers

Adding RDF Model (instances) to Ontology Model using Jena

I am new in semantic web,I want to make an ontology based data base. i created an ontology using protégé then using java i created an ontology model(ontologyModel), also to convert relationnel data base to RDF i used D2RQ then modify the mapping…
MIRIBEL
  • 11
  • 2
1
vote
1 answer

d2rq generate-mapping command for Oracle database

I'm trying to call the d2rq generate-mapping command for Oracle databases from command line. My command string is: C:\d2rq-0.8.1> generate-mapping -o output.ttl -u user -p pass -d oracle.jdbc.driver.OracleDriver…
Akai
  • 11
  • 3
1
vote
0 answers

Federated search on D2RQ

I'm using D2RQ to map relational database to an RDF format. Everything works fine except when I want to do a federated search from another endpoint I'm seeing this in a log file: Query execution error: com.hp.hpl.jena.sparql.ARQNotImplemented:…
marko3d
  • 111
  • 2
1
vote
1 answer

Visualizing D2R rdf data using lodlive

I working on publishing linked data. and I used D2R to publish data from relational database. Now, I need to visualize these data, so I wanted to use lodlive script. I got the project source code from https://github.com/withjam/ml-lodlive#dataset I…
Wisamx
  • 183
  • 3
  • 12
1
vote
0 answers

Storing modified 3rd party configuration files in svn

I'm running a project which includes 2 instances of D2RQ, which is a (third-party) Tomcat application that I'm compiling myself with ant using the supplied build.xml. Currently, I have a copy of the D2RQ code outside of my main development…
ChrisW
  • 4,970
  • 7
  • 55
  • 92
1
vote
1 answer

RDF change the format to include prefix

I am using d2rq.org to change my relational database data to RDF format, which i can write the result dump using http://d2rq.org/dump-rdf and i did that, but the generated triples are as: …
Ania David
  • 1,168
  • 1
  • 15
  • 36
1
vote
1 answer

How to combine multiple MySQL databases using D2RQ?

I have four different MySQL databases that I need to convert into Linked Data and then run queries on the aggregated data. I have generated the D2RQ maps separately and then manually copied them together into a single file. I have read up some…
kurious
  • 1,024
  • 10
  • 29
1
vote
0 answers

Communications link failure when I connect to MySQL database using D2RQ library

I have a question: I have a web service which runs on a virtual machine located on a remote server with Ubuntu 12.04 operating system. Now, I want to test this Web Service and I'm using this code that I have developed in my Web Service…
Musich87
  • 562
  • 1
  • 12
  • 31
1
vote
2 answers

How I can write a file using relative path in Java

I have a question: I have this Java Code: public void generate_mapping() throws FileNotFoundException { String fileMapping = "./src/mappingFile.ttl"; SystemLoader loader = new SystemLoader(); File f = new…
Musich87
  • 562
  • 1
  • 12
  • 31
1
vote
1 answer

D2R 0.8.1 integration with Jena TDB

I am using D2R server for RDB to RDF conversion. Now I want to save this rdf into Jena TDB backed dataset while I am using D2R server. In short I want to integrate Jena TDB with D2R. Code for RDB to RDF conversion is: public static void main…
Suryansh
  • 11
  • 2
1
vote
0 answers

Different query results when using D2RQ from browser and using Jena API

I am trying to run a query using D2RQ. When I run the query using the browser from http://localhost:2020/sparql as described in Using the D2RQ Engine with Jena, everything works fine, but with the Jena API it does not produce any results. The query…
Keks
  • 77
  • 7
0
votes
1 answer

Cannot create blank nodes from D2RQ mapping

I have one table (FCT_POPULATION) with the following structure, representing a quantity of a range over the years for a single city. So, in the same year, I have two quantities, varying according to a range (ids 1 or 2): CITY_ID | YEAR | RANGE_ID |…
Bruno
  • 87
  • 9
1
2 3