RDF::TriG reader/writer

TriG reader/writer for RDF.rb .


This is a Ruby implementation of a TriG reader and writer for RDF.rb.


RDF::TriG parses [TriG] into statements or quads. It also serializes to TriG.

Install with gem install rdf-trig

  • 100% free and unencumbered public domain software.

  • Implements a complete parser and serializer for TriG.

  • Compatible with Ruby 3.x, and JRuby 9+.

  • Optional streaming writer, to serialize large graphs


Instantiate a reader from a local file:

repo = RDF::Repository.load("etc/doap.trig", :format => :trig)

Define @base and @prefix definitions, and use for serialization using :base_uri an :prefixes options.

Canonicalize and validate using :canonicalize and :validate options.

Write a repository to a file:

RDF::TriG::Writer.open("etc/test.trig") do |writer|
   writer << repo

Note that reading and writing of graphs is also possible, but as graphs have only a single context, it is not particularly interesting for TriG.


Both reader and writer include provisional support for RDF-star.

Internally, an RDF::Statement is treated as another resource, along with RDF::URI and RDF::Node, which allows an RDF::Statement to have a #subject or #object which is also an RDF::Statement.

Note that this requires the rdfstar option to be se.

Note: This feature is subject to change or elimination as the standards process progresses.


Full documentation available on Rubydoc.info.

Principle Classes

Implementation Notes

This version uses a hand-written parser using the Lexer from the [EBNF][] gem instead of a general [EBNF][] LL(1) parser for faster performance.

The reader uses the Turtle parser. The writer also is based on the Turtle writer.

The syntax is compatible with placing default triples within {}, but the writer does not use this for writing triples in the default graph.

There is a new :stream option to RDF::TriG::Writer which is more efficient for streaming large datasets.



The recommended installation method is via RubyGems. To install the latest official release of the RDF::TriG gem, do:

% [sudo] gem install rdf-trig

Mailing List



  • Do your best to adhere to the existing coding conventions and idioms.

  • Don’t use hard tabs, and don’t leave trailing whitespace on any line.

  • Do document every method you add using YARD annotations. Read the tutorial or just look at the existing code for examples.

  • Don’t touch the .gemspec, VERSION or AUTHORS files. If you need to change them, do so on your private branch only.

  • Do feel free to add yourself to the CREDITS file and the corresponding list in the the README. Alphabetical order applies.

  • Do note that in order for us to merge any non-trivial changes (as a rule of thumb, additions larger than about 15 lines of code), we need an explicit public domain dedication on record from you, which you will be asked to agree to on the first commit to a repo within the organization. Note that the agreement applies to all repos in the Ruby RDF organization.


This is free and unencumbered public domain software. For more information, see unlicense.org/ or the accompanying UNLICENSE file.

A copy of the TriG EBNF and derived parser files are included in the repository, which are not covered under the UNLICENSE. These files are covered via the W3C Document License.