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Re: JSON-LD serialization and linked data support

From: Benjamin Young <bigbluehat@hypothes.is>
Date: Thu, 13 Aug 2015 14:34:09 -0400
Message-ID: <CAE3H5FL36h33uzTP_wwFmntGeVp5Ty3A9dP6ZyUURHV1qt_4Vg@mail.gmail.com>
To: Ivan Herman <ivan@w3.org>
Cc: James M Snell <jasnell@gmail.com>, Frederick Hirsch <w3c@fjhirsch.com>, W3C Public Annotation List <public-annotation@w3.org>, Tim Cole <t-cole3@illinois.edu>, Rob Sanderson <azaroth@stanford.edu>
On Thu, Aug 13, 2015 at 12:10 PM, Ivan Herman <ivan@w3.org> wrote:

>
> > On 13 Aug 2015, at 17:06 , James M Snell <jasnell@gmail.com> wrote:
> >
> > If I can interject a few thoughts from the sidelines... I faced a
> > similar decision with regards to Activity Streams 2.0 -- only I came
> > at it from the opposite point of view. That is, we had a pure JSON
> > syntax to start and moved to a Vocabulary model with a JSON-LD syntax.
> > One of the key goals of this move, however, has been to make sure that
> > developers who wish to ignore the JSON-LD processing model can do so
> > if they wish -- albeit at a cost of some features.
> >
> > The short version of the story is that Activity Streams 2.0 builds on
> > JSON-LD but requires only a subset of what JSON-LD provides. For
> > instance, the data format *requires* JSON-LD compact form
> > serialization, it requires use of a normative JSON-LD @context
> > definition that ensures consistent serialization, it strongly
> > recommends that certain JSON-LD features are avoided, and -- perhaps
> > most importantly -- does not require that developers implement the
> > full RDF world view in order to make sense of the data.
> >
>
> FWIW, we have arrived to something similar in the CSV on the Web Working
> Group. That WG defines a metadata for CSV data; the format is JSON-LD
> compatible but we, essentially, defined a subset that should be manageable
> without a JSON-LD tools. We actually pushed back on features that would
> have required such tools.
>

Do you have a link for that? I'd like to read up. :)

Cheers!
Benjamin


>
> Ivan
>
>
> > A similar approach can be applied here. By defining a normative
> > JSON-LD @context and requiring compact serialization using that
> > @context, and by limiting the JSON-LD specific features you depend on,
> > you can place practical limits on those various JSON-LD idiosyncrasies
> > that everyone loves to hate.
> >
> > - James
> >
> > On Thu, Aug 13, 2015 at 6:16 AM, Ivan Herman <ivan@w3.org> wrote:
> >> Frederick, I put Tim and Rob into the Cc list just to make it clear
> that this is not a direct answer to this mail but, rather, the three mails
> in this thread ([1,2]), and also Rob's separate mail[3].
> >>
> >> (Apologies if parts of what I write is obvious to some of the people on
> the group. It may not be for others…)
> >>
> >> The annotation model is *not* in JSON-LD. Nor is it in Turtle, for that
> matter. It is in RDF. RDF is defined in terms of abstract concepts (IRI-s
> as identifiers, literals, blank nodes, triples, etc.) defined in the RDF1.1
> Concept document[4]; that document is *serialization agnostic*. (<digress>
> it has been one of the biggest mistake ever in the history of RDF that the
> concept and a particular serialization in XML, ie, RDF/XML, have been
> conflated in the story line. This has done more harm to RDF than anything
> else!</digress>). There are quite a number of serialization syntaxes
> (Turtle, JSON-LD, RDFa, N-Triples, RDF/XML, there is even a simple JSON
> serialization, though not as a Rec).
> >>
> >> I believe that, at this point, nobody (including Paolo) is considering
> moving away from the model. It is a model in RDF and, so far, it has served
> us well. In other words, we are firmly in the domain of Linked Data. We
> should get this issue off the table.
> >>
> >> RDF can be serialized. We use already two of those in our document:
> Turtle and JSON-LD. Other people may use other serialization for OA: RDFa
> or, (God forbid!) RDF/XML. The model is oblivious to that and we cannot
> even forbid that to happen.
> >>
> >> In my *personal* opinion, Semantic Web people would use Turtle, which
> is a simple, straightforward representation of the model. But it is an
> alien syntax to most, so we decided to push JSON to the fore. To achieve
> that, we are looking at a particular *serialization* of RDF, which is
> JSON-LD. We are hoping that this works for us, including those among us who
> do not care about RDF. But JSON-LD has its idiosyncrasies that some may
> live with, but others do not. It has the advantage of being a generic RDF
> serialization, but it also has the disadvantage of being a generic RDF
> serialization:-)
> >>
> >> Here comes Paolo's proposal (at least the way I understand it): let us
> *replace* the JSON-LD serialization with a dedicated JSON serialization of
> our model. Ie, we drop the -LD *from the syntax* (but that does not mean
> dropping Linked Data) and we may replace it with -OA to yield something
> like JSON-OA. What a JSON-LD processor does is to map a generic JSON-LD
> file to the abstract RDF model; well, we can define a processor that does
> the same *to a very restricted JSON syntax* that is defined for the
> annotation model only. There is no real interoperability issue: we drop
> JSON-LD, and we require JSON-OA to be the interchange format; for Linked
> Data aware systems there is a processor that maps this the internal
> representation of RDF, whereas non-Linked Data aware systems can use that
> particular JSON dialect only.
> >>
> >> In fact, this is not so far off from what Rob proposed in [1]:
> >>
> >> [[[
> >> * Define the model to fully encapsulate all of the requirements without
> taking into consideration any serialization or convenience.
> >> * The on-the-wire bits are the JSON-LD serialization of that model. We
> can discuss later whether we need to require a specific crystalization or
> whether we can just say JSON-LD.
> >> * We provide implementations that take that serialization and further
> compact it into whatever structure is most useful, but those are
> non-normative. They're code that we can write to make developers' lives
> easier.
> >> ]]]
> >>
> >> But, I think:
> >>
> >> * Per point 1: we have the model, and we should not change it
> >> * Per point 2: we can, actually, use JSON-OA as a the on-the-wire bits
> as a serialization of that model (yeah, I know, this is a bit touchy with
> the definition of LDP, let us see whether we can solve that)
> >> * Per point 3: JSON-OA *may* be the normative serialization and we
> ditch JSON-LD altogether
> >>
> >> This approach may or may not work. Tim may be right that the proper
> modeling of the problem area would lead us to a certain level of
> complication anyway, and the whole thing may not lead to a real
> simplification compared to JSON-LD. In which case we declare this a dead
> end and we may be stuck with JSON-LD. But let us not pretend that by trying
> to that we create more interoperability problems (we don't, because there
> is a plethora of RDF serializations out there already) or that we drop
> Linked Data approach from our model (we don't because we touch only a
> particular serialization of the model).
> >>
> >> Ivan
> >>
> >> P.S. a different remark: yes, JSON-LD is included in schema.org, ie,
> Google think it is ready and easy for… webmasters! Not developers in
> general…
> >>
> >>
> >> [1]
> http://www.w3.org/mid/CABevsUFyszpujiZq2qGd-wUQVvzzBgHY6K9sAKcatyjdj16PUA@mail.gmail.com
> >> [2] http://www.w3.org/mid/009201d0d585$696b9810$3c42c830$@illinois.edu
> >> [3]
> http://www.w3.org/mid/CABevsUGMeisPtx3xgxv1Dy52nmnUuoaRwWfi2Q10X5QJhr-0JA@mail.gmail.com
> >> [4] http://www.w3.org/TR/rdf11-concepts/
> >>
> >>
> >>> On 13 Aug 2015, at 24:15 , Frederick Hirsch <w3c@fjhirsch.com> wrote:
> >>>
> >>> On today's call the topic of serializations came up and a question
> seemed to be raised over whether JSON-LD should be used (perhaps I heard
> incorrectly)
> >>>
> >>> There are some strong reasons to continue to require JSON-LD as a
> mandatory serialization, the abstract argument being the value of linked
> data on the back end.
> >>>
> >>> A specific concrete example of the value of linked data in combination
> with annotations might be "CATCH: Common Annotation, Tagging, and Citation
> at Harvard"
> >>>
> >>> [[
> >>>
> >>> It is designed to interoperate with third-party annotation tools to
> aggregate and associate contextualized annotation metadata from various
> pedagogical and research tools with reference to persistent digital media
> in repositories, such as the Harvard Library DRS. - See more at:
> https://osc.hul.harvard.edu/liblab/projects/catch-common-annotation-tagging-and-citation-harvard#sthash.fr7L4qa3.dpuf
> >>>
> >>> ]]
> >>>
> >>> Do we have other concrete examples of how the linked data aspect of
> the Open Annotation model adds value to annotations? Pointers would be
> welcome.
> >>>
> >>> I'm concerned about specifying multiple serializations as we have to
> be more careful of interoperability in this case, specifically is
> round-tripping without information loss despite the serialization a
> potential issue? More serializations also mean more testing.
> >>>
> >>> In a related thought, is directly embedding JSON-LD in HTML (
> http://www.w3.org/TR/json-ld/#embedding-json-ld-in-html-documents ) a
> viable option? What is the status of browser support for this? If it is
> supported (or is in progress) what is the case for HTML serialization as an
> alternative? Would it be more productive to focus on generic support for
> JSON-LD in browsers rather than a specific annotation serialization?
> >>>
> >>> The fundamental issue I heard us discuss is that even with all our
> efforts to simplify the JSON-LD serialization, there will remain some
> aspects that do not appear 'natural' to JSON developers.  The next question
> I have is whether these aspects can be managed with suitable libraries etc.
> >>>
> >>> Thanks
> >>>
> >>> regards, Frederick
> >>>
> >>> Frederick Hirsch
> >>>
> >>> www.fjhirsch.com
> >>> @fjhirsch
> >>>
> >>>
> >>
> >>
> >> ----
> >> Ivan Herman, W3C
> >> Digital Publishing Activity Lead
> >> Home: http://www.w3.org/People/Ivan/
> >> mobile: +31-641044153
> >> ORCID ID: http://orcid.org/0000-0003-0782-2704
> >>
> >>
> >>
> >>
> >
>
>
> ----
> Ivan Herman, W3C
> Digital Publishing Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> ORCID ID: http://orcid.org/0000-0003-0782-2704
>
>
>
>
>
Received on Thursday, 13 August 2015 18:34:41 UTC

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