JSON-LD

JSON-LD, or JavaScript Object Notation for Linked Data, is a method of transporting Linked Data using JSON. It was a goal to require as little effort as possible from developers to transform their existing JSON to JSON-LD.^[1] This allows data to be serialized in a way that is similar to traditional JSON.^[2]

JSON-LD is designed around the concept of a "context" to provide additional mappings from JSON to an RDF-like model. The context links object properties in a JSON document to concepts in an ontology. In order to provide some basic interoperability with RDF, JSON-LD allows values to be coerced to a specified type or to be tagged with a language. A context can be embedded directly in a JSON-LD document or put into a separate file and referenced from different documents (from traditional JSON documents via an HTTP link header).

Example

{  "@context": { "name": "http://xmlns.com/foaf/0.1/name", "homepage": {  "@id": "http://xmlns.com/foaf/0.1/workplaceH omepage",  "@type": "@id" }, "Person": "http://xmlns.com/foaf/0.1/Person"  },  "@id": "http://me.markus-lanthaler.com",  "@type": "Person",  "name": "Markus Lanthaler",  "homepage": "http://www.tugraz.at/"}

The example above describes a person, based on the FOAF vocabulary. First, the two JSON properties name and homepage and the type person are mapped to concepts in the FOAF vocabulary and the value of the homepage property is specified to be of the type @id, i.e., it is specified to be an IRI in the context definition. Based on the RDF model, this allows the person described in the document to be unambiguously identified by an IRI. The use of resolvable IRIs allows RDF documents containing more information to be transcluded which enables clients to discover new data by simply following those links; this principle is known as Follow Your Nose.^[3]

By having all data semantically annotated as in the example, a RDF processor can identify that the document contains information about a person (@type) and if the processor understands the FOAF vocabulary it can determine which properties specify the person’s name and the homepage of th person.

Criticism

JSON-LD has been criticised during the standardisation process by Semantic Web commentators for its lack of interoperability with RDF, even though it is being standardised inside of the W3C RDF Working Group ^[4].

References

1. ^ "JSON-LD Syntax 1.0". 2011-12-27. http://json-ld.org/spec/latest/json-l d-syntax/. Retrieved 2011-12-30.
2. ^ "On Using JSON-LD to Create Evolvable RESTful Services". http://m.lanthi.com/jsonld4rest-paper., M. Lanthaler and C. Gütl in Proceedings of the 3rd International Workshop on RESTful Design (WS-REST 2012) at WWW2012.
3. ^ "Linked Data Patterns, Chapter 5: Follow Your Nose". 2011-12-27. http://patterns.dataincubator.org/boo k/follow-your-nose.html. Retrieved 2011-12-30.
4. ^ "Re: Potential Formal Object from DERI over JSON-LD". 2012-10-18. http://lists.w3.org/Archives/Public/p ublic-rdf-wg/2012Oct/0101.html. Retrieved 2013-03-10.

External links

• JSON-LD.org