W3C Workshop on Social Standards/Property Graphs

There was a substantial amount of interest in Property Graphs expressed at the W3C Workshop on Social Standards held yesterday and today in San Francisco [1]. This should lead to a W3C community group to look at standardizing data formats, APIs and serialization formats.

My perspective was that this can certainly be built on generalized RDF, and could be done on standard RDF. There are two ways in which I could so supporting PG in RDF:

1) Put every statement to which link attributes need to be made into a separate named graph, and assert properties on the graph name,
2) Mint a URI (perhaps document-relative) as a property and assert an rdfs:subPropertyOf relationship with the base property, then assert properties on that URI
3) In generalized RDF, create a BNode as the predicate, and assert statements as in 2). (Note, JSON-LD supports this if the produceGeneralizedRdf option is specified in toRdf.

I think this is a compelling use for blank-node predicates, although I believe it is out of scope for RDF 1.1.

Given that a CG may be created with the intention of creating a standards-track for Property Graphs, it's important that this not be at odds with RDF. I don't expect that there's anything that this iteration of the RDF WG can or should do about this at this late date, but it's worth keeping on the list of issues to be considered for a future working group.

There's a related conversion on public-linked-json discussion edge attributes in JSON-LD [2]. I showed an example of how this might be done in JSON-LD:

[
  {"@id": "", "@type": "rdf:BoundDataset"},
  {"@id": "v1", "name": "joe", "age": 27, "_:created": "v3", "_:knows": "v2"},
  {"@id": "v2", "name": "fred", "age": 29},
  {"@id": "v3", "name": "code", "lang": "javascript"},
  {"@id": "_:created", "rdfs:subPropertyOf": "created", "weight": 0.4}
  {"@id": "_:knows", "rdfs:subPropertyOf": "knows", "weight": 0.5}
]

Gregg Kellogg
gregg@greggkellogg.net

[1] http://www.w3.org/2013/socialweb/
[2] http://lists.w3.org/Archives/Public/public-linked-json/2013Jul/0124.html