RE: Reconciling hydra rest semantics for collections with typical RDF entity relationships

When we were trying to develop a container concept here, we went down both the RDF collection route as well as the way that Hydra is currently designed.  Both ways ended up being insufficient beyond the simplistic case for a workable application.  After discovering the Linked Data Platform specs, specifically the ldp:Container we finally had a solution for describing collections in a generic and usable way.  I would recommend looking at http://www.w3.org/TR/ldp/ for more ideas.

/Paul Kuykendall

-----Original Message-----
From: Gregg Kellogg [mailto:gregg@greggkellogg.net]
Sent: Tuesday, February 04, 2014 1:27 PM
To: Kingsley Idehen
Cc: public-hydra@w3.org
Subject: Re: Reconciling hydra rest semantics for collections with typical RDF entity relationships

On Feb 4, 2014, at 10:59 AM, Kingsley Idehen <kidehen@openlinksw.com> wrote:

> On 2/4/14 1:26 PM, Markus Lanthaler wrote:
>> This is a general problem of RDF. AFAICT, there's no way general way
>> to solve this issue for sets. If you would use a list, you could at
>> least use the list's head node (which generally is a blank node).
>> Remember our discussions in the JSON-LD group?
>>
>> Both Schema.org with its ItemList and Hydra with its Collection take
>> a rather pragmatic approach. We could of course go ahead and define a
>> Collection's semantics so that
>
> I assume you've looked at RDF Schema vocabulary which does describe RDF Collections [1] and Containers [2].

I believe Markus' was referring to RDF Collections when he said "list". Of course, a big problem with collections is the navigation cost in RDF, and you can't really chain lists together, presuming that they're conformant BNode-type lists. You also can't refer to such a list, as it also must start with a BNode (to be conformant, not from a vocabulary perspective).

Containers don't work well for a remote list of values, as they use a separate statement for each value, and you can't refer to an external container holding such values.

Another vocabulary to consider is the Ordered List Ontology [3].

Gregg

> [1] http://www.w3.org/TR/rdf-schema/#ch_collectionvocab
> [2] http://www.w3.org/TR/rdf-schema/#ch_containervocab .
[3] http://smiy.sourceforge.net/olo/spec/orderedlistontology.html
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>
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Received on Tuesday, 4 February 2014 19:43:09 UTC