RDF I/O with RIOT

RIOT - RDF I/O Technology - is a code library to support parsing and writing of RDF in non-XML formats. At the moment, the module is focused on input.

Currently supported input syntaxes are:

• Turtle
• N-Triples
• TriG
• N-Quads

Contents

• Status
• Commands
• Inference
• API
• Output and Logging
• Wiring into Jena
• Notes
• See Also
• Contributions
• Support

Commands

There are Linux bash scripts in /ARQ/bin to run these commands, and indirection scripts that can be drop into any directory on the PATH.

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

The file extensions are:

• .nt - N-triples
• .ttl - Turtle
• .nq - N-Quads
• .trig - TriG

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.

Each script calls a Java program.

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

• --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 of triples or quads.
• --time: Output timing information.

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 codepoints are defined.

• 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 subclass, subproperty, domain and range.

API

The formal, stable API to RIOT does not yet exist. Future code reorganized will occur but there are there are certain key classes that provide access to the facilities:

• RiotReader - create parsers
• RiotLoader - parse into datasets and graphs
• WebReader - read data fro the web (content negotiation etc) [Not implemented]
• SysRIOT - constants and setup

Output and Logging

Messages from RIOT are output using SLF4J. Any logging system that provides an implementation or adapter for SLF4J can be used to direct the output. This includes Apache log4j and java.util.logging.

The logger name is "org.openjena.riot" (the constant SysRIOT.riotLoggerName), and the logger can be obtained using the call SysRIOT.getLogger().

Wiring into Jena

The call SysRIOT.wireIntoJena() will replace the usual Jena readers with the RIOT ones. Then calls to Model.read() for the appropriate syntax will use the RIOT parsers.

The usual Jena readers can be reinstalled with SysRIOT.resetJenaReaders()

Notes

N-Quads: only IRIs for the fourth field are supported.

For TriG and N-Quads, bNode labels are assumed to be file-scoped. (See here for a discussion.)

See Also

Notes on RDF syntaxes (June 2010)

Contributions

Please send patches to Apache Jena JIRA.

Support

Please email users@jena.apache.org.