- From: Aaron Bradley <aaranged@gmail.com>
- Date: Thu, 26 Mar 2015 09:49:58 -0700
- To: Martin Hepp <martin.hepp@unibw.de>
- Cc: Jarno van Driel <jarnovandriel@gmail.com>, ☮ elf Pavlik ☮ <perpetual-tripper@wwelves.org>, W3C Web Schemas Task Force <public-vocabs@w3.org>, Gregg Kellogg <gregg@greggkellogg.net>
- Message-ID: <CAMbipBvFrY-=C2Dbsn7af5wu6zvUg9tVEhUQBiFAEf=Yky4Esg@mail.gmail.com>
Very much in agreement with you say Martin, yes. :) On Thu, Mar 26, 2015 at 9:47 AM, Martin Hepp <martin.hepp@unibw.de> wrote: > Aaron: I think we are in agreement regarding the conclusion: Because MTEs > are slippery ground, at least currently, we should keep Vehicle where it is > now. > > I also agree that it would be very desirable if the sponsors of schema.org > could properly support and document the use of MTEs. That is in the long > run better than gradually moving more and more types beneath Product; and > we also need MTEs for ProductModel cases anyway. > > Martin > > -------------------------------------------------------- > martin hepp > e-business & web science research group > universitaet der bundeswehr muenchen > > e-mail: martin.hepp@unibw.de > 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 > > > > > > On 26 Mar 2015, at 17:41, Aaron Bradley <aaranged@gmail.com> wrote: > > > And since partial confirmation by GWT can hardly be considered proof > that it's fine to use MTEs it would indeed be very nice if all the sponsors > could inform us where they stand in regards to MTEs - something which is > long overdue IMHO. > > > > Big +1 to this. From a webmaster's perspective the value in using > structured data markup to improve the search engines' understanding of the > resources being provided to them obviously hinges on whether or not the > search engines can properly process and understand the markup being > provided to them. > > > > "I hope ... that practically maybe ... can happen ... it is unclear .. > room for trouble" > > > > Selective pulling of qualifiers not directed at you, Martin, but by > means of illustrating that in regard to MTEs none of the sponsors, AFAIK, > have said so much as one word on employing them, leaving everyone guessing > and webmasters with exactly no confidence about the impact of employing > MTEs. For my part I shy away from using MTEs because they may well do more > harm than good. > > > > In light of this, I think it's a very bad idea indeed to have any > examples that employ MTEs in schema.org examples until there's clarity > surrounding this, e.g. [1]: > > > > <body vocab="http://schema.org/" itemscope itemtype=" > http://schema.org/VideoGame http://schema.org/MobileApplication"> > > > > Is this robust syntax for Google? Bing? Yahoo? Yandex? Who knows! > Try using the flagship product of that first-listed entity... > > > https://www.google.com/search?q=multiple%20entities%20schema.org&pws=0&hl=en&num=10 > > ... and the results are largely circular, pointing straight back to the > discussions that take place here. > > > > For the record, Google has a page [2] with a heading "Multiple entities > on the same page" that speaks not at all to syntax, but unhelpfully says > that "When you have multiple entity types on a page, we recommend you mark > up all entities on that page" without providing either guidance or examples > that illustrate how to do this in a Google-approved fashion. > > > > If this is indeed "a collection of schemas that webmasters can use to > markup HTML pages in ways recognized by major search providers" then don't > provide me with HTML that is not recognized by the major search providers, > or that nobody knows is recognized by the major search providers. > > > > [1] http://schema.org/VideoGame > > [2] https://developers.google.com/structured-data/policies > > > > > > On Thu, Mar 26, 2015 at 8:52 AM, Martin Hepp <martin.hepp@unibw.de> > wrote: > > > > On 26 Mar 2015, at 15:58, Jarno van Driel <jarnovandriel@gmail.com> > wrote: > > > > > "Thus an MTE in Microdata cannot formally have the properties from > that second type." > > > > > > Yes and no. Yes in a sense that the microdata specs say state that as > long as the types are from the same vocabulary all is fine: > > > > > > The itemtype attribute, if specified, must have a value that is an > unordered set of unique space-separated tokens that are case-sensitive, > each of which is a valid URL that is an absolute URL, and all of which are > defined to use the same vocabulary. The attribute's value must have at > least one token. > > > > > > > Yes, but note that there are two issues: > > > > 1. You must use the Microdata way of multi-typed entities > (space-separated list of types); additionalType will formally not work > (practically maybe). > > > > 2. Properties in Microdata are bound to a type; the notion of global > property identifiers is specific to schema.org and RDF environments. It > can happen that the meaning of the same property is different for two > types. Then, if that property is attached to a multi-typed entity, it is > unclear to which definition and which role of the entity it belongs. > > > > I do not think this is currently a problem, due to the global definition > of properties in schema.org, but I have been advocating for long to > weaken that notion of a globally consistent vocabulary. Should we once > follow this route, the MTE approach can cause trouble. > > > > Also, validator can run into problems if cardinality constraints or > ranges for properties differ by the entity type. For instance, something is > a Book and a Product, and a book must have a weight, while a Product must > have one (hypothetically). > > > > Now, a validator must decide which requirement prevails. Without > overseeing all possible cases right now, I assume there is room for trouble. > > > > > No in sense that this wouldn't work if one uses multiple vocabularies. > Which is something we might consider trying to change as I think it's weird > that RDFa and JSON-LD do allow this, making this situation confusing for > publishers to say the least. > > > > Yes, fixing Microdata would help. Or publishing a note that says that > the sponsors of schema.org consider additionalProperty fully equivalent > to rdf:type and tolerate multi-type entities on this basis. > > > > Martin > > > > > > > > 2015-03-26 15:48 GMT+01:00 Martin Hepp <martin.hepp@unibw.de>: > > > In general I agree. > > > > > > Note, however, that MTE in microdata are problematic, because > additionalType does not formally make the properties from that second type > valid properties for the entity, according to the Microdata spec, because > the vocabulary of the main type defines the finite list of properties > available for that type. Thus an MTE in Microdata cannot formally have the > properties from that second type. > > > > > > I think this is more of a problem of Microdata than schema.org and I > hope that Google and all others are tolerating such additional properties, > though. > > > > > > Martin > > > > > > -------------------------------------------------------- > > > martin hepp > > > e-business & web science research group > > > universitaet der bundeswehr muenchen > > > > > > e-mail: martin.hepp@unibw.de > > > 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 > > > > > > > > > > > > > > > > > > On 26 Mar 2015, at 15:44, Jarno van Driel <jarnovandriel@gmail.com> > wrote: > > > > > > > "IF we can establish it as a standard that products are multi-typed > entities and IF all major consumers of schema.org markup can process this" > > > > > > > > I know from Google's Webmaster Tools reports that Google parses MTEs > quite fine, although I can't tell from those whether they 'understand' them > as well or use MTE data for their search results. > > > > > > > > And since partial confirmation by GWT can hardly be considered proof > that it's fine to use MTEs it would indeed be very nice if all the sponsors > could inform us where they stand in regards to MTEs - something which is > long overdue IMHO. > > > > > > > > 2015-03-26 15:26 GMT+01:00 Martin Hepp <martin.hepp@unibw.de>: > > > > IF we can establish it as a standard that products are multi-typed > entities and IF all major consumers of schema.org markup can process > this, then it would indeed good to > > > > > > > > - move all subtypes of Product up to a new branch of Thing > > > > - move up all properties of Product that are not tied to the Product > role up to that subtype(s) of Thing (e.g weight) > > > > > > > > The historic reason for having Car etc. below Product was that > > > > > > > > - we could not rely on multi-typing, because in Microdata, > multi-typed entities are not fully supported (we have additionalProperty > and multi-types from the same vocab are in general okay, but there are > unresolved problems with properties in this case) > > > > > > > > - human users are more likely to use such types properly if they see > all properties that apply, i.e. such from the nature of the product and > from the product role. > > > > > > > > GoodRelations has always relied on the multi-type approach, but in a > bit more complicated manner, see > > > > > > > > > http://wiki.goodrelations-vocabulary.org/Documentation/Extensions (a bit > outdated) > > > > http://wiki.goodrelations-vocabulary.org/Vocabularies > > > > > > > > But as said, I am happy to clean this up if the two preconditions > above are met. > > > > > > > > Martin > > > > > > > > -------------------------------------------------------- > > > > martin hepp > > > > e-business & web science research group > > > > universitaet der bundeswehr muenchen > > > > > > > > e-mail: martin.hepp@unibw.de > > > > 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 > > > > > > > > > > > > > > > > > > > > > > > > On 26 Mar 2015, at 14:35, ☮ elf Pavlik ☮ < > perpetual-tripper@wwelves.org> wrote: > > > > > > > > > Hello, > > > > > > > > > > As I understand Product acts as Class for adding e-commerce aspect > to > > > > > other Things. Most likely to use it with "@type": ["Book", > "Product"] or > > > > > additionalType when used in microdata. > > > > > > > > > > I don't understand why Vehicle landed as subClassOf Product? I also > > > > > don't understand which other things may end up subclassing Product > in > > > > > the future and which will for example subclass CreativeWork or > Place. > > > > > > > > > > IMO Vehicle, just as Place could directly subclass Thing. Or we > could > > > > > also add Tangible class to deal in a future with with Device etc. > (e.g. > > > > > http://schema.org/MedicalDevice) > > > > > > > > > > It reminds me about my question long time ago about POI (Point Of > > > > > Interest). Which also doesn't make that much sense in class > hierarchy > > > > > but could similar as Product serve as a class to use in addition to > > > > > other classes. > > > > > > > > > > I haven't worked with ruby programming language for quite some > time, but > > > > > in some ways I see similarity to Class vs. Module (besides many > other > > > > > differences from Object Oriented Programming, single parent doesn't > > > > > apply here as well) > > > > > This answer has relevant example which happens to use a Vehicle > > > > > > http://stackoverflow.com/questions/1282864/ruby-inheritance-vs-mixins/1282895#1282895 > > > > > > > > > > In a way Product sounds to me as something more in direction of > > > > > 'Commercial' or broader 'Economic'. > > > > > > > > > > Thoughts? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
Received on Thursday, 26 March 2015 16:50:30 UTC