- From: Gregg Kellogg <gregg@greggkellogg.net>
- Date: Tue, 30 Oct 2012 14:44:36 -0400
- To: Gavin Carothers <gavin@carothers.name>
- CC: Manu Sporny <msporny@digitalbazaar.com>, RDF WG <public-rdf-wg@w3.org>
On Oct 30, 2012, at 11:16 AM, Gavin Carothers <gavin@carothers.name> wrote: > On Tue, Oct 30, 2012 at 11:03 AM, Manu Sporny <msporny@digitalbazaar.com> wrote: >> We had a small side-discussion at the F2F meeting today about >> differences between lists in the JSON-LD data model and lists in the RDF >> data model. This devolved/evolved into a re-hash of the JSON-LD data >> model vs. the RDF data model discussion: >> >> http://www.w3.org/2011/rdf-wg/wiki/JSON-LD_Data_Model >> >> I was going to start by ranting about RDF lists, but it seems I already >> did that back in May: >> >> "I really hate RDF Lists" >> http://lists.w3.org/Archives/Public/public-rdf-wg/2012May/0098.html >> >> Not having Graph/Dataset Literal as a primitive in RDF is also harming >> the RDF data model. We should be able to place a graph/dataset literal >> in the object position of an RDF triple. I don't expect that this group >> will be able to resolve either issue, but I just thought I'd throw this >> out there so that some of you might understand what is lacking in the >> RDF data model. >> >> Resolving these two issues above would help align the JSON-LD data model >> with the RDF data model, specifically: >> >> 1. "Graph names can be blank nodes." The question of whether or not >> graph names can be blank nodes would have to be answered. I'd argue >> that you should be able to name graphs using blank nodes. > > We did resolve this. Graph labels must be IRIs. Yes, we agreed to this. >> 2. "Lists are part of the data model." Lists are part of the data model >> would be true for both models. >> 3. "Graphs/datasets are 'allowed' in the object position." Graphs would >> be "allowed" in the object position in both models. > > We did resolve this, we are not specifying graph literals nor dataset > literals at this time. Yes, my understanding that if an object defining a named graph is used as a property value of another object, what is asserted is that the name is an object, not the graph. E.g.: { "@id": "foo", "dc:title": "Foo", "bar": { "@id": "baz", "@graph": { "dc:title": "Baz" } } } says that there's a graph name "baz" with a single triple [] dc:title "Baz". The TriG should like the following: {<foo> dc:title "Foo"; <bar> <baz>.} <baz> {[dc:title "Baz"]} Gregg >> >> We have simple answers to some of the other differences that would align >> the two data models. >> >> 1. "Unconnected nodes (IRIs, blank nodes or values) are supported." We >> should add: "Authors SHOULD NOT use unconnected nodes (a node >> definition that does not contain any properties) in JSON-LD >> documents." >> 2. "Edge labels may be blank nodes." We should add: "Authors SHOULD >> NOT use blank nodes as edge labels." >> 3. "Language tags are not normalized to lower case." We should add: >> "JSON-LD processors MUST normalize all language tags to lowercase >> when processing documents via the JSON-LD Algorithms." >> 4. "Scope of blank node labels". We should add: "Blank node labels are >> scoped to the JSON-LD document." >> >> Which leaves these two differences between the JSON-LD data model and >> the RDF data model: >> >> 1. "Supports 'plain' strings, numbers and booleans, separately from >> typed literals." This is true for TURTLE as well, so if there is a >> problem with JSON-LD, then there is a problem with TURTLE when it >> comes to this issue. >> 2. "Language maps are part of the data model." This is syntactic sugar >> that was a requested "deal breaker" feature by the Drupal community. >> If we don't include it, Drupal will willfully violate the JSON-LD >> spec (or come up with their own solution). Digital Bazaar's >> implementations will support Drupal by adding the feature to the >> implementation, thus willfully violating the JSON-LD spec. The >> difference in the data model does not result in any loss of >> information when converting to RDF, other than the ability to >> re-create the exact JSON-LD language-map structure when converting >> back to JSON-LD from RDF. I personally don't think people will >> care about not being able to round-trip language-maps from >> JSON-LD to RDF and back to JSON-LD, but if they do, Gregg Kellogg >> has proposed a mechanism that allows that to happen. >> >> Hope that is a helpful rundown of the differences between the two data >> models and my personal opinion of where we should be headed wrt. data >> model alignment. >> >> -- manu >> >> -- >> Manu Sporny (skype: msporny, twitter: manusporny) >> President/CEO - Digital Bazaar, Inc. >> blog: HTML5 and RDFa 1.1 >> http://manu.sporny.org/2012/html5-and-rdfa/ >> >
Received on Tuesday, 30 October 2012 18:45:31 UTC