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Re: Enumeration values

From: <tomasz@t-code.pl>
Date: Sat, 10 Jan 2015 07:32:55 +0000
Message-ID: <e24f4a2725f9d34c100ed573a1859678@rainloop.t-code.pl>
To: "Dietrich Schulten" <ds@escalon.de>, public-hydra@w3.org
Hi Dietrich,

I don't like the duplicate hydra:allowedIndividual(s) property. using @type seems intuitive but I guess we don't to have an individual used as a class. So how about simply "hydra:individual"? This would be more in line with supportedProperty/property pair. Also do we already have the hydra:title defined? If not I'd simply used rdfs:label.

  "@type": "Property",
  "hydra:allowedIndividual": [
  { "hydra:individual": "EventCancelled", "rdfs:label": "..." },
  { "hydra:individual": "EventPostponed", "rdfs:label": "..." }


January 10 2015 7:52 AM, "Dietrich Schulten" <ds@escalon.de> wrote: 
> In order to get internationalized captions for allowed individuals one could do the following. If
> :allowedIndividuals is expected to contain objects with an attribute :allowedIndividual
> (:allowedIndividuals :range :AllowedIndividual), one can use that with "@type":"vocab" to interpret
> the values as individuals in the default vocab, here enum values in schema.org (see below and [1]).
> Drawback: If someone just wants enum values without captions, things are more complicated than
> necessary.
> Opinions?
> Assuming that the client requested Italian as language (the other language facilities of json ld
> such as @language or language map would work, too [2]).
> {
> "@context": {
> "@vocab": "http://schema.org/",
> "hydra": "http://www.w3.org/ns/hydra/core#",
> "hydra:allowedIndividual": {
> "@type": "@vocab"
> },
> },
> ...
> "hydra:supportedProperty": [
> {
> "hydra:property": "eventStatus",
> "hydra:allowedIndividuals": [
> {
> "hydra:allowedIndividual": "EventCancelled",
> "hydra:title": "manifestazione annullata"
> },
> {
> "hydra:allowedIndividual": "EventPostponed",
> "hydra:title": "manifestazione rinviata"
> }
> ]
> }
> ]
> ...
> }
> In JSONLD-Playground:
> [1] http://tinyurl.com/qz85ep6
> [2] http://tinyurl.com/om7fsqc
> Am 09.01.2015 um 18:03 schrieb Dietrich Schulten:
>> I was considering to use oslc:allowedValue in hydra-java but wasn't sure if I could use it
> because
>> its value is explicitly a reference to another class, not an embeddable restriction - and I need
> it
>> in embedded form for the moment.
>> I see the label-value problem, too. I'll try to make it work with @type:vocab.
>> On January 9, 2015 5:17:38 PM Kev Kirkland <kev@dataunity.org> wrote:
>>> Just to chime in - I agree also. 
>>> I've implemented the 'oslc:allowedValue' system from Resource Shape 2.0 [1] in the AngularJS
>> Hydra
>>> client [2]. It's a stop gap solution as I needed something working in a hurry for Data Unity. I
>>> went with OSLC as it was quick to understand and implement, but I'm very open minded about other
>>> solutions.
>>> One of the issues I've found with 'oslc:allowedValue' is that I can't find a way to specify a
>> label
>>> for an RDF literal 'enum' value. This means the label in the HTML option list matches the
> literal
>>> value used in the vocab, which isn't always easily understood by the user. This could well be
>> down
>>> to my lack of understanding about OSLC though.
>>> I've only put 'oslc:allowedValue' directly on the resource representation at this stage, so I
>>> haven't figured out how to integrate it closely with Hydra. The AngularJS Hydra client looks for
>>> OSLC information on the Resource when building the Form view, then uses it to populate HTML drop
>>> downs on the page.
>>> Cheers,
>>> Kev
>>> [1] http://www.w3.org/Submission/2014/SUBM-shapes-20140211/
>>> [2] https://github.com/dataunity/dataunity-hydra-client
>>> On 9 January 2015 at 15:23, Thomas Hoppe <thomas.hoppe@n-fuse.de> wrote: 
>>>> Hi,
>>>> I just wanted to add that I consider the case Dietrich is describing;
>>>> in my own words:
>>>> Specifying expected properties _plus_ a range/ resource/ collection/ enumeration
>>>> of potential values a very important one.
>>>> Ex: User profile creation case where you ask for the country of
>>>> residence of a user and expect an item from a resource in the same API as value.
>>>> I wanted to bring up this case earlier but wanted to wait until we have resolved the
>>>> "easy" scenarios.
>>>> I also think that OWL restrictions are probably too hard to understand/ implement
>>>> and that only because of this I think that having a property like `hydra:range`
>>>> could make sense.
>>>> Greets, Thomas
>>>> On 01/06/2015 12:21 PM, Dietrich Schulten wrote:
>>>>> Hash: SHA1
>>>>> Am 05.01.2015 um 11:15 schrieb Ruben Verborgh:
>>>>>> HI Dietrich,
>>>>>> [From issue text:]
>>>>>>>> Isn't that part of ontological modelling, and thus
>>>>>>>> part of the
>>>>>>>> property?
>>>>>>> I do not think the ontological model of a property covers it.
>>>>>> Perhaps not all cases, but I think for many.
>>>>>>> On the one hand, sometimes not all possible values are
>>>>>>> predefined, but they may be extensible by individuals from other
>>>>>>> vocabs, see the usage of goodrelations enums from schema.org.
>>>>>> In that case, you might have a more specific property. (But I
>>>>>> realize this modeling-based solution is not for everybody.)
>>>>> What about the other hand [from issue text]?
>>>>>>> On the other hand, while a value might occur on a class in
>>>>>>> general,
>>>>> it might not be suitable in a particular context.
>>>>> For instance, assume that only the creator of an event should be able
>>>>> to cancel it altogether (PUT eventStatus EventCanceled), others can
>>>>> only change the status to rescheduled or postponed. Or, let's say it
>>>>> should only be possible to reschedule an event as long as we are more
>>>>> than two weeks away from the event date.
>>>>> As a REST service implementor I would like to tell the client exactly
>>>>> which status changes are available for a resource right now.
>>>>> Are there OWL constructs which would allow me to do so?
>>>>> BTW, the Resource Shapes paper [1] section 4 discusses another point
>>>>> why OWL is not well suited to describe application constraints. As
>>>>> they put it, "Unfortunately, an OWL reasoner will go to great lengths
>>>>> to make some superficially inconsistent looking graphs consistent". By
>>>>> saying that a property :owner is a :functionalProperty of a
>>>>> :ChangeRequest, I do not prevent people to post a ChangeRequest with
>>>>> two owners :Bob and :Joe. A reasoner would simply infer that :Bob and
>>>>> :Joe must be the same resource and happily accept the change request.
>>>>>>> If you think rdfs:range, it is not about value constraints but
>>>>>>> inference, so it doesn't enumerate possible values at all (I've
>>>>>>> learned that much by now). Or do you have something else in
>>>>>>> mind?
>>>>>> OWL does it. I understand most people don't want to go that
>>>>>> “complex” (even though it's quite alright), but we should just be
>>>>>> aware that a modeling-based solution also exists.
>>>>> And it would have the beauty that it is already available and the
>>>>> concepts are known, at least by modelers. I would certainly prefer
>>>>> that over defining new hydra properties.
>>>>> What do you have in mind, maybe owl:Restriction?
>>>>>> For example: foaf:knows has a range of foaf:Person. If we're
>>>>>> developing a social application, it might make sense to restrict
>>>>>> this to only people on the network. Yet listing them exhaustively
>>>>>> would probably not make sense. So then perhaps a ex:knows
>>>>>> (subproperty of foaf:knows) where the range is “people from the
>>>>>> network” makes sense.
>>>>> But how can I express a Range "people from the
>>>>> network", given that
>>>>> the number of people on the network is dynamic? You bring up an
>>>>> interesting point. A ReST service would also want to tell the client:
>>>>> use this link (or IriTemplate) to get a hydra:Collection of allowed
>>>>> values. A third property hydra:allowedResources which may contain an
>>>>> IriTemplate or a plain Resource which can be dereferenced into a
>>>>> Collection or PagedCollection could achieve that. I'll update #82
>>>>> accordingly [2] and see which comments I get :)
>>>>> The original purpose of #82 is to have a means to list a rather
>>>>> limited number of possible values and to leverage @type:@vocab for
>>>>> enumerated values like http://schema.org/DeliveryMethod which has
>>>>> members from goodrelations.
>>>>> [1] http://events.linkeddata.org/ldow2013/papers/ldow2013-paper-02.pdf
>>>>> [2] https://github.com/HydraCG/Specifications/issues/82
>>>>> - -- 
>>>>> Dietrich Schulten
>>>>> Escalon System-Entwicklung
>>>>> Bubenhalde 10
>>>>> 74199 Untergruppenbach
>>>>> -----BEGIN PGP SIGNATURE-----
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>>>>> =z5B1
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>>> --  www.dataunity.org twitter: @data_unity
Received on Saturday, 10 January 2015 07:33:45 UTC

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