Position:

JSON-LD is a standards-track specification for describing linked data in JSON, with an emphasis on maintaining an idiomatic JSON representation, but allowing unique identifiers to be associated with resources and properties. Being a product of the RDF Working Group, it is also a concrete RDF syntax, able to express the entirety of the RDF data model, including data sets.

JSON-LD has received broad adoption, even before being released as a recommendation. Early adopts include DBpedia and Drupal, and most recently Google has endorsed it as an alternative for representing metadata in HTML documents and as a way to add dynamic controls to email messages [4]. Indeed, JSON-LD provides particularly simple markup when working within a single vocabulary, such as schema.org: by using http:/schema.org/ as the context for a document, all properties and types are implicitly taken from schema.org, making publishing data in this vocabulary trivial.

Recently, there as been some uptake in the Activity Streams community [5]. This is a natural way to use JSON-LD, and applications such as Activity Streams are really the target JSON-LD. The core principles of JSON-LD are to allow authors to work in idiomatic JSON, meaning using JSON as they normally would without consideration to working within an RDF data model. This makes applications such as Activity Streams, which use standard JSON conventions for represent ion information, work quite well; all that's necessary is a supplementary context to be able to associate IRIs with terms (JSON keys) used within a document.

Social vocabularies are also converging on schema.org for defining vocabulary terms; this is evident in examples from the Acttivity Streams 2.0 proposal.

Broad adoption of JSON-LD, particularly by schema.org partners, makes the use of JSON-LD and schema.org a natural progression for social platforms such as Activity Streams.

[1] http://www.slideshare.net/gkellogg1/json-for-linked-data
[2] http://www.slideshare.net/gkellogg1/jsonld-and-mongodb
[3] http://www.slideshare.net/gkellogg1/jsonld-linked-data-for-web-apps
[4] http://blog.schema.org/2013/06/schemaorg-and-json-ld.html
[5] https://raw.github.com/jasnell/json-activity/2.0/json-activity-2.txt