Reading and Writing RDF in Apache Jena

This page details the setup of RDF I/O technology (RIOT).

Formats

The following RDF formats are supported by Jena. In addition, other syntaxes can be integrated into both the parser and writer registries.

  • Turtle
  • RDF/XML
  • N-Triples
  • JSON-LD
  • RDF/JSON
  • TriG
  • N-Quads
  • TriX
  • RDF Thrift

RDF/JSON is different from JSON-LD - it is a direct encoding of RDF triples in JSON. See the description of RDF/JSON.

RDF Thrift is a binary encoding of RDF (graphs and datasets) that can be useful for fast parsing. See the description of RDF Thrift.

Command line tools

There are scripts in Jena download to run these commands.

  • riot - parse, guessing the syntax from the file extension. Assumes N-Quads/N-Triples from stdin.
  • turtle, ntriples, nquads, trig, rdfxml - parse a particular language

These can be called directly as Java programs:

The file extensions understood are:

 Extension    Language 
.ttl Turtle
.nt N-Triples
.nq N-Quads
.trig TriG
.rdf RDF/XML
.owl RDF/XML
.jsonld JSON-LD
.trdf RDF Thrift
.rt RDF Thrift
.rj RDF/JSON
.trix TriX

.n3 is supported but only as a synonym for Turtle.

In addition, if the extension is .gz the file is assumed to be gzip compressed. The file name is examined for an inner extension. For example, .nt.gz is gzip compressed N-Triples.

These scripts call java programs in the riotcmd package. For example:

java -cp ... riotcmd.riot file.ttl

This can be a mixture of files in difefrent syntaxes when file extensiosn are used to determine the file syntax type.

The scripts all accept the same arguments (type "riot --help" to get command line reminders):

  • --syntax=NAME; Explicitly set the input syntax for all files.
  • --validate: Checking mode: same as --strict --sink --check=true.
  • --check=true/false: Run with checking of literals and IRIs either on or off.
  • --sink: No output.
  • --time: Output timing information.
  • --out=FORMAT: Output in a given syntax (this is streaming, not pretty printing).

To aid in checking for errors in UTF8-encoded files, there is a utility which reads a file of bytes as UTF8 and checks the encoding.

  • utf8 -- read bytes as UTF8

Inference

RIOT support creation of inferred triples during the parsing process:

riotcmd.infer --rdfs VOCAB FILE FILE ...

Output will contain the base data and triples inferred based on RDF subclass, subproperty, domain and range declarations.