tomatophantastico / sparqlmap-legacy

SparqlMap - A SPARQL to SQL rewriter based on R2RML

#SparqlMap

SparqlMap - A SPARQL to SQL rewriter based on R2RML specification.

It can be used in allows both extracting RDF from an relational database and rewrite SPARQL queries into SQL.

##Current Status

We have refactored SparqlMap in the last few months a lot. The current master branch is not yet ready for prime time, thus no binary release are out yet.

If you want to try out SparqlMap, best use a binary distribution from our [old website] (https://code.google.com/p/sparqlmap/downloads/list).

##Convert Relational Database into RDF

Most of the time, dump creation will take place on the command line. In the binary distributions these can be found in the bin folder. The two files of interest are:

./bin/dump.sh             (1)
./bin/generateMapping.sh  (2)

(1) dump will create an full RDF representation based on a mapping provided. (2) will generate that mapping for you, based on the Direct Mapping specification. You can use this mapping as a starting point. However, be aware that the full database will be mapped and that the mapping will apear clumsy.

Rewrite SPARQL queries into SQL

For rewriting SPARQL queries into SQL SparqlMap can expose a SPARQL endpoint by an embedded tomcat. The enpoint is started by

java -jar sparqlmap-X.X.X-with-dependencies.jar

This will expose an SPARQL endpoint with a little snorql interface.

R2RML conformance

SparqlMap conforms fully with the R2RML specification and was tested with PostgreSQL, MySQL and HSQL. The test results can be found in the repository.

Project Structure

This project has the following sub-folders:

• sparqlmap-core The rewriting (and the dumping) mechanics can be found here.
• sparqlmap-web The code for exposing webservices resides here.
• sparqlmap-webinterface The yeoman client-side webinterface is here.
• sparqlmap-shared Common resources, like exemplary mappings, local versions of vocabularies and default config files are here.
• sparqlmap-cli The command line wrapper around thecore.
• sparqlmap-r2rmltestcases The SparqlMap R2RML testrunner and the results of these test are here.

sparqlmap-legacy's Issues

maven artifacts not dereferencable

The gradle build fails, as the aksw-commons parent project cannot be dereferenced

Empty hsql db generates invalid SQL

A non-empty mapping together with an empty hsqldb table generates a SQL query without a from clause, which is valid for mysql and postgresql, but not for hsqldb.

Passing the conf folder via jndi/context.xml expects sparqlmap.properties

implement fallback to default

Fix jena <-> R2RML default graph uri

Allow SPARQL queries over cli

beside dumping and mapping generation, allow querying on the command line.

Implement Aggregate functions and Subqueries.