JSON for linked data - migrating to RDF

Shuffl [1] is the tool we're planning to use to annotate ADMIRAL [9] datasets and submissions.  For ease of implementation Shuffl was initially written to use JSON data formats for persisting data.  It was always my intention that Shuffl should use RDF, and I've recently being working through some of the changes required to support this for ADMIRAL.

Recently, my attention was drawn to a blog post [2] by Sandro Hawke [8] titled From JSON to RDF in Six Easy Steps with JRON, which starts out with the observation "Sometimes, if you stand in the right place and squint, JSON and RDF line up perfectly". It goes on to describe a strategy for representing RDF in JSON that aims to retain the convenience of JSON while being capable of representing full gamut of valid RDF.  It happens that the format described is fundamentally similar to the format I've been using to serialize Shuffl data.  This leads me to consider that JRON could be a great way to make RDF programmer-friendly, and provide a migration path for all the web applications that offer and consume JSON data serialization to participate in the web of linked data.

I've also been experimenting with Jeni Tennison's rdfquery [3] plugin for jQuery [4]. This was a natural choice for use with Shuffl, which is also extensively based on jQuery. It turns out that rdfquery is a gem of a library that seems to be not widely used.  It cleverly manages to bridge the conceptual gap between jQuery-style document access and SPARQL-style dataset queries.

My most recent development has been to implement a JRON-to-rdfquery mapping [5][6][7] as a jQuery plugin.  The implementation is mostly-complete with respect to the JRON specification [2] - for more details of its status see [6].  In the process of creating this implementation, a couple of issues have been raised concerning the design of JRON:

• representing RDF statements about multiple "root" subjects, and
• handling "bare" URIs when a default (i.e. blank) prefix is defined

The first of these is not yet resolved, though I'm in discussion with Sandro.  I've resolved the second by introducing an N3-like option to wrap full URIs in angle brackets.

So How does this relate to migrating a JSON application? My migration plan for Shuffl, as of late July 2010 is in two phases, the first of which is essentially a fairly complex refactoring:

• create a plugin framework for Shuffl to use alternative data serialization formats (done).
• create a plugin to support the current JSON serialization (done)
• modify Shuffl to use the plugin framework (not done)

The second phase introduces the new RDF-related functionality into Shuffl:

• implement a mapping between JRON [2] and rdfquery databank [3] (done)
• modify Shuffl to use a JRON-compatible JSON format (not done)
• implement a serialization plugin to map Shuffl/JRON to RDF, via an rdfquery databank (not done)

at which point, Shuffl should be capable of reading and writing both JRON and RDF/XML

My original plan was to use this approach to convert Shuffl to using mainly RDF, but looking back I can see some attraction in promoting JRON as a first-class citizen in the linked data world.  Compared with RDF, it's really easy to read and write for common data objects.  The existence of relatively simple syntax-transformation software to map between JRON and "proper" RDF shows that interoperability need not be hard to achieve  (my implementation took about 3-4 days, and much of that was building up the test suite). And a format for RDF that is close to "native" JSON means that it is much easier to write simple browser mashup-style applications that can consume and do cool things with this data.

[1] http://code.google.com/p/shuffl/

[2] http://decentralyze.com/2010/06/04/from-json-to-rdf-in-six-easy-steps-with-jron/

[3] http://code.google.com/p/rdfquery/

[4] http://jquery.com/

[5] http://code.google.com/p/shuffl/wiki/JRON_implementation_notes (early design notes)

[6] http://code.google.com/p/shuffl/source/browse/trunk/docs/JRON-for-rdfquery-implementation-notes.txt (post-implementation notes)

[7] http://code.google.com/p/shuffl/source/browse/trunk/src/rdfquery.jron.js (jQuery plugin source)
http://code.google.com/p/shuffl/source/browse/trunk/src/test/test-rdfquery.jron.js (test suite)
http://code.google.com/p/shuffl/source/browse/trunk/static/test/test-rdfquery.jron.html
(test runner - references some other files from http://code.google.com/p/shuffl/source/browse/)

[8] http://www.w3.org/People/Sandro/

[9] http://imageweb.zoo.ox.ac.uk/wiki/index.php/ADMIRAL