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Re: JSON-LD Telecon Minutes for 2013-07-02

From: Robert Sanderson <azaroth42@gmail.com>
Date: Wed, 3 Jul 2013 11:40:40 -0600
Message-ID: <CABevsUFoPE0T9rXdZAEZnpaSH3Da3qYWEuy-iht8vwcbjY=YqQ@mail.gmail.com>
To: Niklas Lindström <lindstream@gmail.com>
Cc: Pat Hayes <phayes@ihmc.us>, Linked JSON <public-linked-json@w3.org>, RDF WG <public-rdf-wg@w3.org>, public-openannotation <public-openannotation@w3.org>
Very good points!

To me at least owl:sameAs is fine as it asserts that the head blank node is
the same resource as the thing with identity (and additional
properties/relationships).  That seems closer to the current Open
Annotation model than using rdf:value.  However, if there's a best practice
that can be recorded, and the overall feeling is that rdf:value or a
different predicate is better suited for this purposes across communities,
then clearly we should use that.

And indeed, owl:sameAs would have the same issue as rdf:value if it wasn't
possible to use different keys in the JSON-LD context to make the
distinction between multiple predicates and a single list as object.  As
contexts are community specific anyway, there doesn't seem to be a need to
standardize exactly what it's called, otherwise it would need to be
@something to reduce unintentional collisions.

Many thanks!

Rob



On Wed, Jul 3, 2013 at 10:09 AM, Niklas Lindström <lindstream@gmail.com>wrote:

> Hi Robert,
>
> Great to hear that we're making progress!
>
> It should be noted though that in JSON-LD you can define different terms
> for the same property, with cases like this in mind. That is, you can
> define a "listValue" term as:
>
>     "listValue": {"@id": "rdf:value", "@container": "@list"}
>
> which ensures that you can still use plain "rdf:value" keys (or for that
> matter, define another term for it, like "value") with arrays without
> turning those values into @list values. Only the use of the defined
> "listValue" term above would turn the value into a JSON-LD @list (i.e. a
> proper RDF list). Which is what we're after here.
>
> I can understand if "owl:sameAs" feels more semantically apt for your
> needs though, so I hope that works out. Still, in JSON-LD, unless you want
> to use the verbose {"@list": [...]} expression inline all the time, I
> suggest that you define something like this in the @context:
>
>     "isList": {"@id": "owl:sameAs", "@container": "@list"}
>
> Ensuring that you can write things like:
>
>     {
>       "@id": "target1",
>       "@type": "oa:SpecificResource",
>       "oa:hasSelector": {
>         "@id": "list1",
>         "@type": "oa:List",
>         "isList": [1, 2]
>       }
>     }
>
> To get the same RDF as this Turtle:
>
>     <target1> a oa:SpecificResource;
>       oa:hasSelector <list1> .
>     <list1> a oa:List;
>       owl:sameAs ( 1 2 ) .
>
> (Otherwise you have to declare the list like: "owl:sameAs": {"@list": [1,
> 2]}).
>
> Cheers,
> Niklas
>
>
>
> On Wed, Jul 3, 2013 at 5:15 PM, Robert Sanderson <azaroth42@gmail.com>wrote:
>
>>
>> Dear all,
>>
>> TL;DR version:  I think that owl:sameAs is a great solution for the
>> predicate.
>>
>> Thank you for the discussion!
>>
>> The primary use case for lists with identity (and other properties,
>> potentially) in Open Annotation is to have an ordered workflow for
>> selecting the correct part of a document. For example, EPub documents are
>> just zip files with HTML and other resources packed inside them, so it
>> would be beneficial to reuse the methods for selecting the correct segment
>> of a resource on the web with the resources inside the EPub, but first the
>> file within the zip must be selected.
>>
>> Thus we would want:
>>
>> <target1> a oa:SpecificResource ;
>>   oa:hasSelector <list1> ;
>>   oa:hasSource <epub1> .
>>
>> <list1> a oa:List, rdf:List ;
>>   rdf:isList (<FileSelector>, <TextSelector>) .
>> // Or something similar here
>>
>> <FileSelector> a idpf:EpubFileSelector ;
>>   rdf:value "/chapter1.html" .
>>
>> <TextSelector> a oa:TextQuoteSelector ;
>>   oa:prefix "bit before the segment"
>>   oa:exact "The text of the annotated segment"
>>   oa:suffix "bit after the segment"
>>
>>
>> The relevant part of the specification is:
>>     http://www.openannotation.org/spec/core/multiplicity.html#List
>> (and you'll see the long red editor's note!)
>>
>> I think that Pat's suggestion of owl:sameAs is very appropriate. It works
>> in the different syntaxes and has the semantics that the resources are the
>> same -- in the case above the blank node that has first of <FileSelector>
>> and the resource <list1>.
>>
>> The other options discussed were rdf:value, which is extremely fuzzy and
>> in JSON-LD context you couldn't assert that it always had a list as its
>> object if it was also used with a literal. In which case it would result in
>> multiple rdf:value predicates, each with one of the list items as object.
>> That led to discussing a new predicate, such as listItems, listValue,
>> isList, or similar.  This would have the implication that the blank node
>> and the main identified resource were different resources, as compared to
>> the proposal of owl:sameAs which would mean they were the same resource.
>>
>> Rob
>>
>>
>>
>>
>>
>>
>> On Wed, Jul 3, 2013 at 12:30 AM, Pat Hayes <phayes@ihmc.us> wrote:
>>
>>>
>>> On Jul 2, 2013, at 11:38 PM, David Booth wrote:
>>>
>>> > On 07/03/2013 12:07 AM, Pat Hayes wrote:
>>> >>
>>> >> On Jul 2, 2013, at 12:40 PM, Manu Sporny wrote:
>>> >>
>>> >>> Thanks to Niklas for scribing. The minutes from this week's telecon
>>> >>> are now available.
>>> >>>
>>> >>> http://json-ld.org/minutes/2013-07-02/
>>> >>>
>>> >>> Full text of the discussion follows including a link to the audio
>>> >>> transcript:
>>> >>>
>>> >>> -------------------------------------------------------------------
>>> >>>
>>> >>>
>>> > JSON-LD Community Group Telecon Minutes for 2013-07-02
>>> >>>
>>> >>> Agenda:
>>> >>>
>>> http://lists.w3.org/Archives/Public/public-linked-json/2013Jul/0000.html
>>> >>>
>>> >>>
>>> > Topics:
>>> >>> 1. Assigning Properties to Lists 2. GSoC update 3. JSON-LD / RDF
>>> >>> Alignment 4. Lists in the JSON and RDF data models 5. Default
>>> >>> interpretation of JSON arrays Resolutions: 1. Create an issue in
>>> >>> the RDF WG to formalize a way to express lists that need to be
>>> >>> identified with a URL and annotated using properties.
>>> >>
>>> >> If I understand this correctly, this can be done in RDF already. For
>>> >> example, the list [ x:a, x:b, 27 ] identified by the URI ex:thisList
>>> >> and possessing the property x:prop with value x:value is described by
>>> >> this RDF:
>>> >>
>>> >> ex:thisList rdf:type rdf:List . ex:thisList rdf:first x:a .
>>> >> ex:thisLIst rdf:rest _:1 . _:1 rdf:first x:b . _:1 rdf:rest _:2 . _:2
>>> >> rdf:first "27"^^xsd:number . _:2 rdf:rest rdf:nil . ex:thisLIst
>>> >> x:prop x:value .
>>> >
>>> > If I have understood the issue properly, the reason
>>> > for raising this issue in the RDF working group is that this is not
>>> > necessarily an advisable usage pattern for the RDF list vocabulary,
>>> because such a list cannot be serialized using Turtle's list syntax: (x:a
>>> x:b 27).
>>>
>>> Yes, you are right, and I confess I had never noticed this limitation of
>>> Turtle previously. OK, let me change the RDF to the following, keeping the
>>> list bnodes but using owl:sameAs. (You can of course use some other
>>> property indicating equality if y'all prefer.):
>>>
>>> ex:thisLIst rdf:type rdf:List .
>>> ex:thisLIst x:prop x:value .
>>> ex:thisList owl:sameAs _:3 .
>>> _:3 rdf:first x:a .
>>> _:3 rdf:rest _:1 .
>>> _:1 rdf:rest _:2 .
>>> _:2 rdf:first "27"^^xsd:number .
>>> _:2 rdf:rest rdf:nil .
>>>
>>> Or, in Turtle:
>>>
>>> ex:thisList rdf:type rdf:List ;
>>>       x:prop x:value ;
>>>       owl:sameAs (x:a , x:b, 27 ) .
>>>
>>> and you could probably omit the first triple, or even introduce your own
>>> category of JSON-lists and say it is one of those, instead, if that would
>>> help with triggering appropriate translations into other formats (or to
>>> distinguish these from eg RDF lists used to encode OWL syntax.)
>>>
>>> >  It falls into a  similar category as other uncommon uses of the RDF
>>> List vocabulary:...
>>>
>>> ...no, it doesn't. See remark below.
>>>
>>> Pat
>>>
>>> > other uncommon uses of the RDF List vocabulary:
>>> > http://www.w3.org/TR/rdf-schema/#ch_collectionvocab
>>> > [[
>>> > Note: RDFS does not require that there be only one first element of a
>>> list-like structure, or even that a list-like structure have a first
>>> element.
>>> > ]]
>>> >
>>> > While not prohibited by RDF, such uncommon uses of the RDF list
>>> vocabulary are certainly seen by some as being somewhat anti-social. Thus,
>>> the question is whether such uses should be *encouraged*.
>>> >
>>> > David
>>> >
>>> >>
>>> >> Pat
>>> >>
>>> >>> Chair: Manu Sporny Scribe: Niklas Lindström Present: Niklas
>>> >>> Lindström, Robert Sanderson, Markus Lanthaler, Manu Sporny, David
>>> >>> Booth, David I. Lehn, Vikash Agrawal Audio:
>>> >>> http://json-ld.org/minutes/2013-07-02/audio.ogg
>>> >>>
>>> >>> Niklas Lindström is scribing.
>>> >>>
>>> >>> Topic: Assigning Properties to Lists
>>> >>>
>>> >>> Markus Lanthaler: https://github.com/json-ld/json-ld.org/issues/75
>>> >>> Robert Sanderson:  we'd very much like to give rdf:Lists identity,
>>> >>> so that they can be referenced from multiple graphs. Also to
>>> >>> describe them with other properties ... in openannotation, we need
>>> >>> lists to define a selector which determines which part is
>>> >>> annotated ... for instance, which piece of a text is annotated,
>>> >>> with "before" and "after" also recorded (most clients work like
>>> >>> that) ... Futhermore, IDPF has agreed to use openannotation for
>>> >>> all EPub books ... EPubs, being zip files with a bunch of files ...
>>> >>> To define a selector here (take the EPub, select a file, then a
>>> >>> part in there) ... So we don't want to reproduce every single
>>> >>> selector mechanism. Thus, an ordered list of two selectors would
>>> >>> be neeeded. ... We thus need to identify lists, so that we can
>>> >>> reuse these selectors in multiple statements. ... I.e. a person
>>> >>> wants to disagree with a specific annotation, or place being
>>> >>> annotated. ... Furthermore, we have the order of multiple targets,
>>> >>> e..g. "the first passage on page three, is derived from the second
>>> >>> passage on page five" ... Not as essential, since it's not really
>>> >>> machine actionable ... Another project using lists is Shared
>>> >>> Canvas ... We'd very much like to use JSON-LD there too, for
>>> >>> selecting pages, using a list of pages and so forth ... For this,
>>> >>> we took the "list items" approach; the list doesn't need to be
>>> >>> referenced directly. Markus Lanthaler: robert, do you have the link
>>> >>> of an example at hand? ... But it might be nice to have this
>>> >>> standardized, so people don't reinvent list items all the time. ...
>>> >>> at the mailing list and also the OA community meeting in Europe, we
>>> >>> agreed that we don't want to change the model to accomodate
>>> >>> different syntaxes ... We want to recommend JSON-LD Manu Sporny:
>>> >>> what's the timeline for these needs / when would the WG close
>>> >>> Robert Sanderson:  at the moment, the CG is in an implementation
>>> >>> phase. We need to dicuss with Ivan, but we hope to move from CG to
>>> >>> WG next year Manu Sporny:  we're very close to CR in JSON-LD. If
>>> >>> we'd add his feature in, it would put us back for many months.
>>> >>> Could we add this for JSON-LD 1.1? ... If we think we can put the
>>> >>> feature in, I think we can easily convince implementers to add it.
>>> >>> If we add it to the test suite, other implementers would add it.
>>> >>> ... So for practical purposes, we aim for it to be added within a
>>> >>> year or so. Robert Sanderson:  Yes, that approach could work for
>>> >>> us. Given that your'e much further ahead. It's not our prefered
>>> >>> option, since for implementations, it might be unpredictable. ...
>>> >>> Also, changing this for OA now is much easier than when in a WG ...
>>> >>> I don't believe anyone has implemented it yet, but IDPF needs this
>>> >>> to be implementable Manu Sporny:  so we may put it in jSON-LD 1.1
>>> >>> Niklas Lindström:  First thing, as far as I know, Turtle doesn't
>>> >>> support this syntax either. Given that you have a shorthand in
>>> >>> Turtle.... actually, none of the formats in RDF/XML and Turtle
>>> >>> support this sort of list syntax. [scribe assist by Manu Sporny]
>>> >>> Markus Lanthaler: niklasl, AFAICT they currently set rdf:rest to a
>>> >>> Turtle list Niklas Lindström:  Have you discussed that as well? Am
>>> >>> I missing something? [scribe assist by Manu Sporny] Robert
>>> >>> Sanderson:  No, I don't think you missed anything. [scribe assist
>>> >>> by Manu Sporny] Robert Sanderson:  The identity is easier in
>>> >>> RDF/XML - you have the property for the URI. [scribe assist by Manu
>>> >>> Sporny] Robert Sanderson:  We did consider the other
>>> >>> serializations, it's not a ubiquitous feature, but it would be nice
>>> >>> to have in JSON-LD. [scribe assist by Manu Sporny] Niklas
>>> >>> Lindström:  Right, the main argument when we had the issue, even
>>> >>> though it's in the Primer that says there is nothing preventing
>>> >>> lists from being described, multiple start properties, etc. None of
>>> >>> the core syntaxes allow it, it's not intended to be used like that.
>>> >>> [scribe assist by Manu Sporny] Niklas Lindström:  They're supposed
>>> >>> to be used as syntactic constructs.... model-wise, they're not
>>> >>> really a part of RDF.
>>>
>>> That is not correct. Collections were intended to be an integral part of
>>> RDF. They were used by OWL as a syntactic device for encoding OWL syntax in
>>> RDF, making them unavailable inside OWL, but that is an OWL/RDF issue.
>>> (IMO, with hindsight, this was a serious mistake in designing the OWL/RDF
>>> layering. But I was there at the time and didn't see the danger myself, so
>>> mia culpa.)
>>>
>>> >>> [scribe assist by Manu Sporny] Niklas
>>> >>> Lindström:  If this is supported in JSON-LD, it would be a lot
>>> >>> easier to deviate from the recommended usage pattern.... also
>>> >>> making it harder for a future RDF spec, who wants to add lists as a
>>> >>> native part of the model [scribe assist by Manu Sporny] Niklas
>>> >>> Lindström:  You can still use rdf:first / rdf:next explicitly
>>> >>> today. [scribe assist by Manu Sporny] Robert Sanderson:  I agree.
>>> >>> The notion of order in a graph is always problematic. Not the
>>> >>> common method to have a resource that is a list and has identity.
>>> >>> [scribe assist by Manu Sporny] Robert Sanderson:  Maybe RDF
>>> >>> COncepts 1.1 should discuss it. [scribe assist by Manu Sporny]
>>> >>> David Booth:  Yeah, RDF WG should consider this. I agree with
>>> >>> Niklas. It doesn't fit w/ the usual list pattern. Important to
>>> >>> consider implications. [scribe assist by Manu Sporny] ... Here's an
>>> >>> example:
>>> >>> http://www.openannotation.org/spec/core/multiplicity.html#List
>>> >>> Robert Sanderson: That's it exactly, thanks Niklas1 Manu Sporny:
>>> >>> any other thoughs on this? Markus Lanthaler:  it would make it hard
>>> >>> to expect compaction to behave as predicted ... also, compaction
>>> >>> might be more complex Manu Sporny:  Yes. We wanted to stay away
>>> >>> from it since it might be a mine field in general. ... that said,
>>> >>> there might be a case for this. Niklas Lindström:  Agree with
>>> >>> Manu's point - there might be something new that's interesting
>>> >>> here. I don't think we should do it w/o discussing implications.
>>> >>> Algorithmic complexity for JSON-LD API and implementations. It
>>> >>> might be almost as problematic as bnodes as predicates. It's
>>> >>> possible to do this in raw RDF. It seems highly obvious that you
>>> >>> can add ID in other properties. On the other hands you... [scribe
>>> >>> assist by Manu Sporny] Manu Sporny: ...can do it w/ literals.
>>> >>> Niklas Lindström:  This borders on the syntactical collapse.
>>> >>> [scribe assist by Manu Sporny] Markus Lanthaler:  syntactically
>>> >>> having a property carrying the actual list is nearly
>>> >>> indistinguishable as the requested form (using "@list" as key)
>>> >>> Robert Sanderson:  I agree. The easisest solution for everyone
>>> >>> would be to have a "listItem" as a property. ... and for the RDF
>>> >>> WG, it might be good to define a dedicated predicate for it.
>>> >>> rdf:value is explicitly fuzzy, so you can't always expect a list.
>>> >>> David Booth: Robert, would it be feasible to just wrap the list in
>>> >>> another object, and attach the additional info to the wrapper
>>> >>> object? (I apologize that I have not fully grokked the problem, so
>>> >>> this suggestion may not be helpful.) ... It would be easier to sell
>>> >>> changing the model if there was another predicate for this. Manu
>>> >>> Sporny:  so a specific vocabulary for lists would be beneficial in
>>> >>> general, working in all syntaxes ... would that adress this issue?
>>> >>> If we quickly create a list vocabulary? Robert Sanderson:  I think
>>> >>> so. Not preferable duing the discussions we had, but the syntactic
>>> >>> arguments may sway this position. ... A single, interoperable
>>> >>> solution is preferable. Manu Sporny:  anyone objects to open issue
>>> >>> 75, to continue this dicussion? Niklas Lindström:  I think we
>>> >>> should try to have this as an RDF issue - it really would not come
>>> >>> up if lists were core to the RDF model. It's a sore spot in RDF
>>> >>> Concepts. I think we should push it over to the RDF WG immediately.
>>> >>> It's arbitrary if we or OA try to push something forward, it won't
>>> >>> solve the real problem.... not in rdf schema vocab. [scribe assist
>>> >>> by Manu Sporny] Robert Sanderson: +1 to Niklas
>>> >>>
>>> >>> PROPOSAL: Create an issue in the RDF WG to formalize a way to
>>> >>> express lists that need to be identified with a URL and annotated
>>> >>> using properties.
>>> >>>
>>> >>> Manu Sporny: +1 David Booth: +1 Robert Sanderson: +1 Niklas
>>> >>> Lindström: +1 could be someything like rdf:listValue David I. Lehn:
>>> >>> +1 Markus Lanthaler: +1
>>> >>>
>>> >>> RESOLUTION: Create an issue in the RDF WG to formalize a way to
>>> >>> express lists that need to be identified with a URL and annotated
>>> >>> using properties.
>>> >>>
>>> >>> Topic: GSoC update
>>> >>>
>>> >>> Vikash Agrawal:  what's broken in the playground? Manu Sporny:  a
>>> >>> bit weird ui paradigm when clicking on expanded form; headings for
>>> >>> JSON-LD Context stay, but the input box disappears. Markus
>>> >>> Lanthaler: http://www.markus-lanthaler.com/jsonld/playground/
>>> >>> Markus Lanthaler:  the headers stay but the inputs disappear.
>>> >>> Previously headers were toggled off if input areas weren't
>>> >>> applicable Manu Sporny:  play around a bit. I think the old way is
>>> >>> better. There may be something even better, but right now, the
>>> >>> problem is that something not used is still shown. Vikash Agrawal:
>>> >>> this is bug 50 ... by this week, this should be done. Next week is
>>> >>> a creator app. Markus Lanthaler: could we discuss these things on
>>> >>> the mailing list or the issue tracker? Manu Sporny:  email danbri
>>> >>> and gregg regarding a schema.org JSON-LD context Markus Lanthaler:
>>> >>> vikash, here's Sandro's schema.org context:
>>> >>> http://www.w3.org/People/Sandro/schema-org-context.jsonld Markus
>>> >>> Lanthaler: for the creator app, have a look at:
>>> >>> http://schema-creator.org/
>>> >>>
>>> >>> Topic: JSON-LD / RDF Alignment
>>> >>>
>>> >>> Manu Sporny:
>>> >>> http://lists.w3.org/Archives/Public/public-rdf-wg/2013Jun/0233.html
>>> >>>
>>> >>>
>>> > Manu Sporny:  I went into the spec and tried to integrate what we
>>> >>> have consensus on. ... see the email link above for a list of
>>> >>> things. ... everything should be there except for skolemization
>>> >>> David Booth:  I just found it, but I think it looks great (just
>>> >>> some minor things) Manu Sporny:  would it adress the LC comment?
>>> >>> David Booth:  It might. It's in the right direction. Manu Sporny:
>>> >>>
>>> http://json-ld.org/spec/ED/json-ld/20130630/diff-20130411.html#data-model
>>> >>>
>>> >>>
>>> > Manu Sporny:  next, Peter's changes. Appendix A was changed to
>>> >>> flat out say that JSON-LD uses an extended RDF model. ... we just
>>> >>> say "Data Model", and that it's an extension of the RDF data
>>> >>> model. Markus Lanthaler:
>>> >>> http://lists.w3.org/Archives/Public/public-rdf-wg/2013Jul/0010.html
>>> >>>
>>> >>>
>>> > ... we need to have a resonse from Peter on this.
>>> >>> David Booth:  I'd expect it to be, to the extent that I can channel
>>> >>> Peter. David Booth: Every node is an IRI , a blank node , a
>>> >>> JSON-LD value , or a list . David Booth:  restricting the literal
>>> >>> space to JSON-LD values is a restriction rather than an extension
>>> >>> to the RDF model. Robert Sanderson: Sorry, have to attend another
>>> >>> call now, though would like to have stayed for the rest of the
>>> >>> conversation. Thanks everyone for the discussion re lists. ... and
>>> >>> I don't think that lists need to be mentioned there; they are just
>>> >>> sugar. Markus Lanthaler: "A JSON-LD value is a string, a number,
>>> >>> true or false, a typed value, or a language-tagged string." Markus
>>> >>> Lanthaler: thanks for joining robert Manu Sporny:  on top, we
>>> >>> extension the value space to json true and false, numbers and
>>> >>> strings. David Booth: A JSON-LD value is a string , a number , true
>>> >>> or false , a typed value , or a language-tagged string . David
>>> >>> Booth:  it wasn't clear that those lined up with the corresponding
>>> >>> RDF value space. Manu and David agree that the JSON number value
>>> >>> space is more general. Manu Sporny:  different lexical spaces for
>>> >>> booleans in xsd and json
>>> >>>
>>> >>> Topic: Lists in the JSON and RDF data models
>>> >>>
>>> >>> David Booth:  What about lists, aren't they the same as expressed
>>> >>> in RDF? Manu Sporny:  not convinced that they are.. ... we need to
>>> >>> translate it to something in the data model. In RDF, it translates
>>> >>> to the list properties. There is nothing in RDF concepts to point
>>> >>> to. ... many just assumes that it's basically part of the data
>>> >>> model, but it's formally not David Booth:  why not point to rdf
>>> >>> schema? Manu Sporny:  not part of the rdf data model. Niklas
>>> >>> Lindström:  Yeah, just a comment. Could we correlate this RDF
>>> >>> Concepts problem w/ the suggestion wrt. list values. [scribe assist
>>> >>> by Manu Sporny] David Booth: RDF lists: David Booth:
>>> >>> http://www.w3.org/TR/rdf-schema/#ch_list Niklas Lindström:
>>> >>> Clearly, lists are under-specified. [scribe assist by Manu Sporny]
>>> >>> Niklas Lindström:  Maybe we should expand RDF Concepts that is
>>> >>> present in the 2004 Primer and the Syntax that I scanned
>>> >>> previously. [scribe assist by Manu Sporny] Manu Sporny:  but does
>>> >>> rdf schema extend the rdf data model? David Booth:  no, just a
>>> >>> convention which is using the rdf data model Markus Lanthaler:
>>> >>> but's still just a vocabulary. In JSON-LD, we use [a keyword and]
>>> >>> an array ... it's like a node type [just as literals] Manu Sporny:
>>> >>> the JSON-LD data model does not talk about rdf:first and rdf:rest
>>> >>> David Booth:  I don't think any test cases needs to be changed by
>>> >>> the way this is described. So it's just a question of how this
>>> >>> concept is being described. At present, it's described as a
>>> >>> difference. Manu Sporny:  True. We only change how you think about
>>> >>> the data model. Manu Sporny:  if we make an argument about the
>>> >>> difference between native JSON literals and RDF literals, we need
>>> >>> to explain the difference of expressing lists as well. David Booth:
>>> >>> I don't see the benefit as a difference, from an RDF perspective.
>>> >>> Niklas Lindström:  I think I can answer re: benefit of having
>>> >>> different model wrt. JSON lists and RDF lists. In JSON, there are
>>> >>> arrays, those arrays represent repeated statements in RDF> [scribe
>>> >>> assist by Manu Sporny] Niklas Lindström:  RDF people understands
>>> >>> that intuitively. We mention @set because people that don't
>>> >>> understand RDF, but do understand mathematical sets.... ordered
>>> >>> list is more popular than sets in programming. [scribe assist by
>>> >>> Manu Sporny] Niklas Lindström:  We need a way to explain lists in
>>> >>> JSON-LD, in the same way that we explain sets, and other things.
>>> >>> Not in a way that introduces rdf:first and rdf:next. [scribe assist
>>> >>> by Manu Sporny] David Booth: Bottom line: I do not see a need to
>>> >>> call out lists as being a difference from the RDF model, but I'm
>>> >>> okay with it being mentioned, in part because I'd like to push RDF
>>> >>> to have native lists. Markus Lanthaler: manu, did you see
>>> >>> http://lists.w3.org/Archives/Public/public-rdf-wg/2013Jul/0010.html
>>> >>>
>>> >>>
>>> > already?
>>> >>>
>>> >>> Topic: Default interpretation of JSON arrays
>>> >>>
>>> >>> David Booth:  it seems strange to have @set (unordered) as the
>>> >>> default ... in regular json, the default is ordered Markus
>>> >>> Lanthaler:  We discussed this quite a bit in the beginning, the
>>> >>> rationale was that the RDF that was generated would be unmanageable
>>> >>> - lots of blank nodes, lots of rdf:first/rdf:rest, you couldn't
>>> >>> work w/ the RDF anymore. [scribe assist by Manu Sporny] Markus
>>> >>> Lanthaler:  we discussed it quite a bit in the beginning. The
>>> >>> rationale we came up with is that the generated RDF would be very
>>> >>> gruesome, using rdf lists for everything. ... hundreds of blank
>>> >>> nodes for everything. Niklas Lindström:  Yeah, I agree. That's the
>>> >>> rationale. While it's true that arrays in JSON are ordered in their
>>> >>> nature, in all the JSON-LD examples, they are commonly only sets.
>>> >>> There is no real order. JSON-LD is intended to be used w/ RDF
>>> >>> properties, there are only a handful of common RDF properties -
>>> >>> author, contributorList, propertyChainAction, where the order is
>>> >>> semantic, it means something. [scribe assist by Manu Sporny] Niklas
>>> >>> Lindström:  In every other case, it's just a bundle of things. I
>>> >>> think that's the better case - explicitly say order doesn't mean
>>> >>> anything. The same thinking has obscured lots of things wrt. XML.
>>> >>> You can rely on the order of the elements, not sure if you should.
>>> >>> It's better to say that "you can't rely on the order", unless
>>> >>> someone says so explicitly. [scribe assist by Manu Sporny] David
>>> >>> Booth:  As a programmer, I'd use the exact opposite rationale.
>>> >>> [scribe assist by Manu Sporny] David Booth: So if the default were
>>> >>> changed to being ordered, then the examples would have to be
>>> >>> changed to add @set? Markus Lanthaler:
>>> >>> https://github.com/json-ld/json-ld.org/issues/12 Niklas Lindström:
>>> >>> We discussed whether we should do it in the @context, we could
>>> >>> define @set to be the default. [scribe assist by Manu Sporny]
>>> >>> Niklas Lindström:  I agree w/ David that as a programmer, you think
>>> >>> like that. Unless you think otherwise. [scribe assist by Manu
>>> >>> Sporny] David Booth:  There is also minimal changes going from JSON
>>> >>> to JSON-LD. [scribe assist by Manu Sporny] Niklas Lindström:
>>> >>> Datasets on the Web, you never know if the order is intentional or
>>> >>> not. It's better to assume that it's not ordered. [scribe assist by
>>> >>> Manu Sporny] Markus Lanthaler:  JSON-LD can already serialize the
>>> >>> same data in so many ways already - remote contexts, you can't
>>> >>> really interpret the data anymore by just looking at it. Maybe
>>> >>> doing it in a processor flag, but not in the context. [scribe
>>> >>> assist by Manu Sporny] Niklas Lindström:  I'd like to be able to do
>>> >>> this in the context. "@container": "@set" would be useful to me.
>>> >>> [scribe assist by Manu Sporny] David Booth: Can we have a global
>>> >>> way to indicate @set ? Niklas Lindström:  Yeah, but I could wait
>>> >>> for this feature. [scribe assist by Manu Sporny] David Booth:  I'm
>>> >>> worried about the element of surprise. It reverses the common
>>> >>> expectation. Manu Sporny:  It has not come up as a real issue from
>>> >>> anywere though. Markus Lanthaler:  Is there a use case for this?
>>> >>> [scribe assist by Manu Sporny] Markus Lanthaler:  In the majority
>>> >>> of instances, the order is irrelevant David Booth:  yes, quite
>>> >>> possible Manu Sporny:  a change could also backfire at this stage
>>> >>> ... we could potentially have a JSON-LD 1.1, for e.g. this. David
>>> >>> Booth: I think the best solution would be a simple global way to
>>> >>> specify @set, and user get used to always doing that. Niklas
>>> >>> Lindström:  I think that it can't fly from my point of view - given
>>> >>> that for every case where I've seen order having meaning, it's
>>> >>> always been a very specific technical reason. Implicitly ordered
>>> >>> things as properties on the object. In every specific scenario
>>> >>> where order is used.... [scribe missed] [scribe assist by Manu
>>> >>> Sporny] Niklas Lindström:  check out schema.org· only a handful
>>> >>> where the meaning is explicitly ordered:
>>> >>> http://www.w3.org/People/Sandro/schema-org-context.jsonld Niklas
>>> >>> Lindström:  I might be open that it should be ordered, but not by
>>> >>> default. [scribe assist by Manu Sporny]
>>> >>>
>>> >>> -- manu
>>> >>>
>>> >>> -- Manu Sporny (skype: msporny, twitter: manusporny, G+: +Manu
>>> >>> Sporny) Founder/CEO - Digital Bazaar, Inc. blog: Meritora - Web
>>> >>> payments commercial launch http://blog.meritora.com/launch/
>>> >>>
>>> >>>
>>> >>>
>>> >>
>>> >> ------------------------------------------------------------ IHMC
>>> >> (850)434 8903 or (650)494 3973 40 South Alcaniz St.
>>> >> (850)202 4416   office Pensacola                            (850)202
>>> >> 4440   fax FL 32502                              (850)291 0667
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>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >
>>>
>>> ------------------------------------------------------------
>>> IHMC                                     (850)434 8903 or (650)494 3973
>>> 40 South Alcaniz St.           (850)202 4416   office
>>> Pensacola                            (850)202 4440   fax
>>> FL 32502                              (850)291 0667   mobile
>>> phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
>>>
>>>
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>>>
>>
>
Received on Wednesday, 3 July 2013 17:41:17 UTC

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