SPARQL Shell

SPARQL shell is an Apache Jena plugin, that allows executing shell commands as a SPARQL function.

Setup

Build the jar:

mvn package

Copy the resulting package to the 'lib' folder of your Jena installation.

Alternatively grab the JAR from the release on GitHub.

Example usage

To convert Markdown to HTML, we can use the following query:

PREFIX f: <java:eu.europa.ec.sparql.shell.>
SELECT ?s 
{ 
  BIND("# Title\n - Item 1\n - Item 2" as ?t)
  BIND(f:Exec("pandoc -f markdown -t html", ?t) as ?s)

}

This will execute the pandoc tool to do the convertion.

The output of this query is:

--------------------------------------------------------------------------------
| s                                                                            |
================================================================================
| "<h1 id=\"title\">Title</h1>\n<ul>\n<li>Item 1</li>\n<li>Item 2</li>\n</ul>" |
--------------------------------------------------------------------------------

Security consideration

The executed process runs as a subprocess of the Jena SPARQL/Fuseki process. This is a serious security risk. It should not be used in a public endpoint or where the data is untrusted.