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Re: additionalType property, vs extending Microdata syntax for multiple types

From: Guha <guha@google.com>
Date: Sat, 16 Jun 2012 15:41:31 -0700
Message-ID: <CAPAGhv8GMB=915n5QA1F4N_UPT7TpBmcAMOFcf6+e-4WbqGRSQ@mail.gmail.com>
To: Martin Hepp <martin.hepp@ebusiness-unibw.org>
Cc: Peter Mika <pmika@yahoo-inc.com>, Dan Brickley <danbri@danbri.org>, Ivan Herman <ivan@w3.org>, "public-vocabs@w3.org" <public-vocabs@w3.org>, Jeni Tennison <jeni@jenitennison.com>
My personal preference is to just add an attribute called type (or
additionalType) which is samePropertyAs rdfs:type and be done with it.

guha

On Sat, Jun 16, 2012 at 2:25 PM, Martin Hepp <
martin.hepp@ebusiness-unibw.org> wrote:

> Hi Peter,
> the idea behind the additionalType property is two-fold:
>
> First, we wanted an approach that works as of now without requiring an
> update to the MD spec, but can easily be handled in case of a future
> standardization of this.
>
> Second, it preserves the frame-based paradigm of schema.org (and MD
> vocabs, to a lesser extend), where you need a main type for an entity to
> know the set of and definition of suitable properties.
>
> The current workaround is to use the full URI of rdf:type, which is kind
> of an ugly approach:
>
> <div itemscope itemtype="http://schema.org/Product">
>
>    <link itemprop="http://www.w3.org/1999/02/22-rdf-syntax-ns#type" href="
> http://www.productontology.org/id/Laser_printer" />
>
> <!-- other schema.org properties go in here -->
> </div>
>
> So adding  "type" or "additionalType" property to http://schema.org/Thingseems like a quick, pragmatic yet future-prone approach to me.
>
>
> Martin
>
>
> On Jun 16, 2012, at 5:28 PM, Peter Mika wrote:
>
> > Let me add my $0.02...
> >
> > My main concern is that schema.org is and should be about the schema,
> not the syntax. The reason of adding this property is to patch microdata,
> but if schema.org defines this term, it will be available for all
> syntaxes (microdata, RDFa, possibly soon OData). In both microdata and
> RDFa, we would end up with two ways of defining types (using
> typeof/itemtype vs. additionalType). Standard parsers however will only see
> one type (the one expressed using the standard mechanism).
> >
> > A minor concern is that the name additionalType implies that somehow one
> type is more important than the other.
> >
> > Cheers,
> > Peter
> >
> >
> >
> >
> >
> >
> >
> > On 6/16/12 7:48 AM, Dan Brickley wrote:
> >> On 16 June 2012 06:55, Ivan Herman<ivan@w3.org>  wrote:
> >>> On Jun 15, 2012, at 20:26 , Dan Brickley wrote:
> >>>> HTML5 Microdata, as defined in
> >>>>
> http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#encoding-microdata
> >>>>
> >>>> ... has only limited support for describing multiple types that
> >>>> something belongs to. In particular it requires they are described
> >>>> using a single schema.
> >>>>
> >>>>
> >>>> For Good Relations integration (and other scenarios) people have asked
> >>>> for a way of listing more types within schema.org markup.
> >>>>
> >>>> * One model is to use RDFa 1.1 (Lite), where this is quite natural.
> >>>> * Another is to add (as a workaround) a new property, e.g. called
> >>>> 'type' or 'additionalType', to schema.org's vocab (Martin requests
> >>>> this in http://www.w3.org/wiki/WebSchemas/GoodRelations )
> >>>> * A 3rd is to stretch
> >>>>
> http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#items
> >>>> to allow different namespaces to be used.
> >>> I think that the third option is not obvious. The issue is that, in
> microdata, two notions, namely the typing of an item and the vocabulary
> used in that item, are conflated. The vocabulary information (hence the
> interpretation of the terms in the item) is deduced from the itemtype
> value(s). Hence the restriction in the current spec to restrict multiple
> types to be in the same vocabulary. Technically, it would be possible to
> declare that the order in the attribute's value counts, ie, the first type
> value determines the vocabulary, but that would be terribly error-prone and
> I hence do not believe it would be a good idea.
> >>>
> >>> It would require a more substantial change in the microdata spec
> (essentially introducing the equivalent of RDFa's @vocab) to solve that
> properly. I do not see that happening.
> >> Yes. I think it is well appreciated that RDFa 1.1 handles this better.
> >>  I don't think anyone expects Microdata to change a lot more, and I
> >> don't see anyone with the energy/interest to keep pushing for these
> >> kinds of changes/improvements in Microdata. As you say, it wouldn't be
> >> easy. The "main type comes first" design was all I could think of,
> >> too.
> >>
> >>> Which leaves us with the first or the second option. I am obviously
> biased here, but I think the first option is clearly better in this
> respect...
> >> The question is then, what do we say for all those publishers who are
> >> on board the Microdata train? A lot of people have worked hard to get
> >> colleagues/stakeholds (and tools!) adopting Microdata, over the last
> >> year. While RDFa is a good thing, we want to be careful to support
> >> early adopters too, and have sensible advice for them (other than
> >> 're-do everything with a new syntax'). Which is what makes
> >> 'additionalType' attractive. But the concern there is ... if we go
> >> that route, validators/checkers will need to understand the attribute
> >> since it is almost an extension of the underlying syntax...
> >>
> >> cheers,
> >>
> >> Dan
> >
>
> --------------------------------------------------------
> martin hepp
> e-business & web science research group
> universitaet der bundeswehr muenchen
>
> e-mail:  hepp@ebusiness-unibw.org
> phone:   +49-(0)89-6004-4217
> fax:     +49-(0)89-6004-4620
> www:     http://www.unibw.de/ebusiness/ (group)
>         http://www.heppnetz.de/ (personal)
> skype:   mfhepp
> twitter: mfhepp
>
> Check out GoodRelations for E-Commerce on the Web of Linked Data!
> =================================================================
> * Project Main Page: http://purl.org/goodrelations/
>
>
>
>
Received on Saturday, 16 June 2012 23:09:38 GMT

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