Re: Questions about new collection design

Here's a link to a working snippet of what I have in mind, running in the
JSON-LD playground: http://tinyurl.com/loacumv .

It shows a paginated collection of "foaf:knows" values implemented using a
different named-schema per each page of the collection, each with
appropriate pagination links. The normalized output looks fine to me.

Granted, the semantics of "hydra:manages", "hydra:next", etc... etc... are
slightly different than the current ones.


--

Jacopo Scazzosi
Developer
http://www.jacoscaz.com

On Thu, Feb 5, 2015 at 12:29 PM, Jacopo Scazzosi <jacoposcazzosi@gmail.com>
wrote:

> Hello everyone! This is my first message ever to this list - I hope I'm
> off for a good start.
>
> First things first, huge thanks and loud high-fives to all of you. To a
> newcomer to the world of JSON-LD, RDF, LDF and Linked-Data such as I am,
> this list comes as an invaluable source of both theoretical and practical
> understanding.
>
> Now, to the point. I, too, do not like the current collection design that
> is being discussed. Beside not providing the client with explicit
> assertions about the managed predicate, in my *extremely* humble opinion
> this design also confuses the actual triples of interest - representing
> those that alice knows - with triples of a higher-order - such as
> pagination triples - that actually describe the former triples rather than
> alice herself. However... Isn't this what named graphs are for? Being able
> to actually describe sets of triples with other triples?
>
> So, here's my graphs-inspired idea...
>
> {
>   "@id": "/alice",
>   "@type": "foaf:Person",
>   "hydra:graphs": [
>     {"@id": "/alice/graph/knows", "manages": "foaf:knows"}
>   ],
> }
>
>
> {
>   "@id": "/alice/graphs/knows",
>   "isAbout": "/alice",
>   "manages": "foaf:knows",
>   "nextPage": "/alice/graphs/knows?p=2",
>   "@graph":
>   [
>     {"@id": "/alice", "foaf:knows": "/bob"},
>     {"@id": "/alice", "foaf:knows": "/linda"}
>   ]
> }
>
> The general idea is to use dedicated graphs to serialise sets of triples
> that need meta-data for their representations to be of practical use (such
> as query and/or pagination data).
>
> While I do prefer header-based pagination using the "Range" header, this
> solution is pagination-agnostic. It can go with header-based pagination,
> link-based pagination and whatnot. It also explicitly states who is it that
> alice knows, although clients are still required to understand the
> "manages" predicate in order to figure out which link to follow.
>
> That's it.  Please forgive me if I have gotten something wrong, I'm still
> wrapping my head around all this. Also, english is not my first language -
> beware of grammatical and/or syntactical horrors.
>
>
> --
>
> Jacopo Scazzosi
> Developer
> http://www.jacoscaz.com
>
> On Thu, Feb 5, 2015 at 9:22 AM, Dietrich Schulten <ds@escalon.de> wrote:
>
>> Hi Markus, hi Tomasz,
>>
>> Am 03.02.2015 um 21:26 schrieb Markus Lanthaler:
>> > On 3 Feb 2015 at 14:38, Dietrich Schulten wrote:
>> >> Am 25.01.2015 um 23:31 schrieb Markus Lanthaler:
>> >> Question: How to materialize the :knows relationship?
>> >
>> > It would look somewhat like this (please note the additional knownBy
>> > property):
>> >
>> >   {
>> >      "@context": { "knownBy": { "@reverse": "foaf:knows", "@type":
>> "@id" }
>> > },
>> >      "@id": "/alice/friends",
>> >      "@type": "Collection",
>> >      "member": [
>> >        {"@id":"/bob", "foaf:name": "Robert Rumbaugh", "knownBy":
>> "/alice" },
>> >        {"@id":"/zelda", "foaf:name": "Zelda Zackney", "knownBy":
>> "/alice" }
>> >      ]
>> >   }
>> >
>> > Would be interesting to see how well compression works here
>> >
>>
>> OK, now that both you and Tomasz tell me i have to use @reverse I think
>> I'll give in and accept that this is the way the collection design works
>> :) When used with a hydra:Collection, I need to add reverse properties
>> to make the :X :hasProperty :A assertion.
>>
>> Thanks to both of you, anyway.
>>
>> I hate to spoil the party, but honestly, I do not like the design. I
>> tend not to use it in hydra-java for the actual collection, at least not
>> by default. I feel that using this design in services without RDF
>> backend will seriously prevent adoption.
>>
>> IMO it *must* be possible to say
>>
>> "foaf:knows" : { "@id": "/alice/friends" }
>>
>> We stray too far from plain json-ld and also from the simple way other
>> hypermedia types point to collections.
>>
>> I have several other reasons, but I'll stop here.
>>
>> Best regards,
>> Dietrich
>>
>>
>