- From: Stian Soiland-Reyes <soiland-reyes@manchester.ac.uk>
- Date: Mon, 23 Jan 2017 10:56:14 +0000
- To: W3C RDFa Community <public-rdfa@w3.org>, "public-rdf-comments@w3.org" <public-rdf-comments@w3.org>
On Sun, 22 Jan 2017 22:28:47 -0600, Pat Hayes <phayes@ihmc.us> wrote: > I may not be following this discussion properly, but surely it was always > part of the RDF vision, from the beginning, that RDF content, ie RDF graphs, > from various sources can be combined and used in reasoning. (If not, what is > the point of the entire semantic web vision?) So it seems to me to be a > reasonable extrapolation that if AAA and BBB are two surface syntaxes *for > describing RDF graphs*, then the fact that they are different surface syntax > should not be interpreted as carrying the implication that the RDF content > they encode should not be combined into a single RDF graph (however that > graph is encoded.) The combination RDFa+JSON-LD reads to me as just a dialect > for RDF+RDF. I think the main questions in this situation are: 1) Do the 'subdocuments' (each RDF block) have to be semantically consistent? 2) Can blank node identifiers be shared across RDF blocks and syntaxes? I think as HTML as a container of multiple RDF representations has not not been specified, the safest would be to assume each block is a separate RDF subdocument (parsed separately), and do not share blank node identifiers. (you can easily imagine RDFa content and JSON-LD content being generated through quite different code bases and therefore might accidentally share bnode identifiers) However all of these would have the same document URI as the base URI - and be from the same authority (usually the base URI), so it would be weird if they were NOT semantically consistent. So I would say they should be semantically consistent and thus mergable to a single graph - given that you avoid bnode overlap when merging. This is equivalent to retrieving the same URI with different content negotiation, which should yield semantically consistent (if not the same) statements. I think RDFa+JSON-LD should be the same as JSON-LD+JSON-LD, as each JSON-LD block must be parsed separately (eg. they can't share @context) - however RDFa is a single resource across the whole HTML document (but not inside iframes). So my view is that these 3 blocks each describe *different* RDF resources (unless told otherwise through sameAs etc): <html><body> <script type="application/ld+json"> { "@id": "_:b1", "@type": "http://schema.org/Person", "http://schema.org/name": "Jamie Oliver" } </script> <div vocab="http://schema.org/"> <p typeof="Book" about="_:b1">The <strong property="name">Jamie Oliver</strong> biography.</p> </div> <script type="application/ld+json"> { "@id": "_:b1", "@type": "http://schema.org/Restaurant", "http://schema.org/name": "Jamie Oliver" } </script> </body> </html> (because each _:b1 is parsed separately) ..but they should still be semantically consistent (composable in a single graph), e.g. not have incompatible types for a resource with the same absolute URI. As JSON-LD can described named and unnamed @graphs these would be similarly mergable to a single RDF Dataset, as if loaded from multiple .jsonld files. (RDFa does not have a way to do named graphs) -- Stian Soiland-Reyes University of Manchester http://www.esciencelab.org.uk/ http://orcid.org/0000-0001-9842-9718
Received on Monday, 23 January 2017 10:56:46 UTC