- From: Sandro Hawke <sandro@w3.org>
- Date: Sat, 31 Mar 2018 02:19:15 -0400
- To: Ivan Herman <ivan@w3.org>, Dan Brickley <danbri@danbri.org>
- Cc: karlg <karl.geog@gmail.com>, Gregg Kellogg <gregg@greggkellogg.net>, Linked JSON <public-linked-json@w3.org>
- Message-ID: <2eefc106-a977-37bc-aa2f-9ae8db5b0ebb@w3.org>
On 03/31/2018 01:04 AM, Ivan Herman wrote:
>
> I would be very weary going down this line. We are indeed talking
> about, essentially, Property Graphs which is a different data model.
>
I think you mean "wary", but "weary" is a pretty good fit too, I bet :-)
I haven't studied "Property Graphs" to know what their data model is,
but I think what's being proposed here is perfectly reasonable to do
with quads/named-graphs. I don't find the @graph syntax nearly as
readable as some other syntaxes, but the semantics are the same, and
they seem entirely sufficient to me.
Yes, I know formally the semantics aren't 100.00% defined, but I'm
confident they are fine in practice. If you say graph1 is valid from t1
to t2, and some triples are in graph1, it's obvious that you mean the
conjunctions of those triples is valid (asserted, known to be true) from
t1 to t2, and we don't really need some other formal spec to tell us
that. The one thing that's needed is the properties for
valid-time-range. One could perhaps just use dc:temporal.
-- Sandro
> The strength of JSON-LD is that it is a serialization of RDF, thereby
> creating a bridge towards Linked Data. It is not the vocation of
> JSON-LD to redefine the underlying RDF model; by doing so, JSON-LD
> would depart from that connection. Closing the gap between property
> graphs and RDF is a perfectly justifiable discussion to have. But this
> discussion should not happen around JSON-LD.
>
> Note that there were some attempts a few years ago to start more
> serious work on that at W3C but it did not happen due to lack of
> interest; maybe things have changed and this could be looked into again.
>
> Ivan
>
>
>> On 31 Mar 2018, at 01:17, Dan Brickley <danbri@danbri.org
>> <mailto:danbri@danbri.org>> wrote:
>>
>> At Schema.org <http://Schema.org> we can't really claim Role has
>> worked out well. I wouldn't advocate it for this.
>>
>> It would be very interesting if a syntax could be found in JSON-LD
>> 1.1, alongwith an optional named graphs view of the data. This would
>> help close the gap wth Property Graphs too.
>>
>> Dan
>>
>> On Sat, 31 Mar 2018, 00:06 karlg, <karl.geog@gmail.com
>> <mailto:karl.geog@gmail.com>> wrote:
>>
>> Sub-classing schema.org <http://schema.org/> Role, e.g. with
>> SettingRole seems promising, thanks
>>
>> kg
>>
>> {
>>
>> "@context": "http://linkedpasts.org/lp-context.jsonld",
>>
>> "@type": "Place",
>>
>> "name": "Abingdon",
>>
>> “properties”: {“p1”: “___”, ...}
>>
>> "setting": [
>>
>> {
>>
>> "@type": "SettingRole",
>>
>> "setting": {
>>
>> "@type": "Place",
>>
>> "name": "Berkshire"
>>
>> },
>>
>> "startDate": "1600",
>>
>> "endYear": "1974"
>>
>> },
>>
>> {
>>
>> "@type": "SettingRole",
>>
>> "setting": {
>>
>> "@type": "Place",
>>
>> "name": "Oxfordshire"
>>
>> },
>>
>> "startDate": "1974",
>>
>> "endYear": "2018"
>>
>> }
>>
>> ]
>>
>> }
>>
>> On 3/30/18, 4:36 PM, "Gregg Kellogg" <gregg@greggkellogg.net
>> <mailto:gregg@greggkellogg.net>> wrote:
>>
>> On Mar 30, 2018, at 3:09 PM, Karl Grossner
>> <karl.geog@gmail.com <mailto:karl.geog@gmail.com>> wrote:
>>
>> Reopening this thread, as my current challenge relates closely:
>>
>> I'm modeling historical Place attestations for gazetteer
>> applications, and a potential linked.places JSON-LD modeling
>> standard (a la linked.art). The idea is to build upon GeoJSON-LD.
>>
>> Several attributes of Places are temporally indexed; i.e. may
>> have a 'valid period', but are not amenable to event models
>> in the same way as linked.art provenance is.
>>
>> From what I can tell, three options are @graph, n-ary
>> relations, and rdf:Statement reification. I've rendered some
>> sample records below. My question is whether there has
>> emerged a best practice for this general problem of edge
>> attributes. Any comments welcome at this stage. I have been
>> having a conversation with @gklyne on this, here, which may
>> (?) shed further light.
>> https://github.com/LinkedPasts/lp-network/issues/1
>>
>> While we could probably add something to perform reification on
>> expansion, or transformation to RDF, it’s not clear how that
>> would allow you to make statements about the statement, and it’s
>> widely considered an archaic mechanism. And, it would
>> substantially complicate the already complex API algorithms.
>>
>> The issue of edge attributes in JSON-LD is really no different
>> than for RDF in general. While there is no syntax for automatic
>> reification of statements, they can of course be represented in
>> JSON-LD.
>>
>> The RDF 1.1 position is more likely that named graphs can be used
>> for this purpose, although there are no built-in semantics.
>> (Basically, put the statement in a named graph, and then make
>> other meta-statements with the graph name as a subject). Your
>> approach 01 is essentially this.
>>
>> Schema.org <http://schema.org/> takes another approach using the
>> Role class (and sub-classes) [1], and this can be used in JSON-LD
>> to describe information about relationships. This is what I’ve
>> used in some of my own projects.
>>
>> Gregg
>>
>> [1] http://schema.org/Role
>>
>>
>>
>> thanks
>>
>> --------
>>
>> approach 01 (@graph; playground <https://tinyurl.com/y74p3pov> )
>>
>> {
>> "@context":
>> "http://linkedpasts.org/assets/place-v4-context.jsonld",
>> "related": [
>> { "@id": "http://linkedpasts.org/graphs/01",
>> "@graph":
>> {"@id":"myplace:Abingdon","part_of":"myplace:Berkshire"},
>> "when": {
>> "timespans":
>> {
>> "earliestYear": "1600",
>> "latestYear": "1974",
>> "label": "from 17c. to 1974"
>> }
>> }
>> },
>> { "@id": "http://linkedpasts.org/graphs/02",
>> "@graph": {"@id":"myplace:Abingdon",
>> "part_of":"myplace:Oxfordshire"},
>> "when": {
>> "timespans":
>> {
>> "earliestYear": "1974",
>> "latestYear": "2018",
>> "label": "from 1974"
>> }
>> }
>> },
>> { "@id": "http://linkedpasts.org/graphs/03",
>> "@graph": {"@id":"myplace:Oxford",
>> "part_of":"myplace:Oxfordshire"},
>> "when": {
>> "timespans":
>> {
>> "earliestYear": "1000",
>> "latestYear": "2018",
>> "label": "from 11c."
>> }
>> }
>> }
>> ]
>> }
>>
>> approach 02 (per property graph example given in this thread)
>>
>> [
>> {"@id": "", "@type": "rdf:BoundDataset"},
>> {"@id": "p1", "name": "Abingdon", "type": "settlement",
>> "_:parent_p1p3":"p3", "_:parent_p1p4":"p4"},
>> {"@id": "p2", "name": "Oxford", "type": "settlement",
>> "_:parent_p2p4": "p4"},
>> {"@id": "p3", "name": "Berkshire", "type": "county"},
>> {"@id": "p4", "name": "Oxfordshire", "type": "county"},
>> { "@id": "_:parent_p1p3",
>> "rdfs:subPropertyOf": "hasParent",
>> "earliestYear": 1600,
>> "latestYear": 1974,
>> "label": "from 17c. until 1974"},
>> { "@id": "_:parent_p1p4",
>> "rdfs:subPropertyOf": "hasPparent",
>> "earliestYear": 1974,
>> "latestYear": 2018,
>> "label": "from 1974"},
>> { "@id": "_:parent_p2p4",
>> "rdfs:subPropertyOf": "hasParent",
>> "earliestYear": 1000,
>> "latestYear": 2018,
>> "label": "from 11c."}
>> ]
>>
>>
>> ----
>>
>> Karl Grossner
>>
>> Technical Director,
>> World-Historical Gazetteer project for the
>>
>> University of Pittsburgh World History Center
>>
>> @kgeographer
>>
>> Denver, CO
>>
>>
>>
>
>
> ----
> Ivan Herman, W3C
> Publishing@W3C Technical Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> ORCID ID: https://orcid.org/0000-0003-0782-2704
>
Received on Saturday, 31 March 2018 06:19:31 UTC