W3C home > Mailing lists > Public > public-vocabs@w3.org > April 2014

Re: working of schema.org/WebPage

From: Jarno van Driel <jarno@quantumspork.nl>
Date: Thu, 17 Apr 2014 20:15:43 +0200
Message-ID: <CAFQgrbZCG7USSZ7JSu092c2RLCj5Z6X3T+abgq6vQMxsqedQfQ@mail.gmail.com>
To: Jason Douglas <jasondouglas@google.com>
Cc: Public Vocabs <public-vocabs@w3.org>
"...if a relation is declared without an explicit subject, then the subject
will be assumed to be the current WebPage."
Got it.

"It is legal for there to be multiple top-level entities." + "Current
clients make up their own heuristics for this..."
Brainfreeze!
How am I, as a developer, to deal with this? Does this mean I have to
somehow figure out which heuristics every parser/search engine uses, to be
able to have control or do I need to try to chain everything together such
that only one top-level entity is left?

And how would I do this for a category page on for example an eCommerce
site. Which shows a range of Product entities on a CollectionPage, which
together form the main-content and where the CollectionPage, for lack of a
better term, only functions as a 'wrapper' for the list of products.

"we probably do need a mechanism for indicating the "primary entity" of a
webpage when there is one..."
One the reasons why I asked my questions is because I encounter quite a lot
of markup on websites where people use @mainContentPage on entities like
Product. Now @mainContentOfPage has the expected type WebPageElement, but
many aren't aware of this. And since there is no property to indicate which
entity is the primary one I actually can completely understand they try to
resolve it like this. And frankly, I'm confused as well.



On Thu, Apr 17, 2014 at 7:51 PM, Jason Douglas <jasondouglas@google.com>wrote:

> It is legal for there to be multiple top-level entities.  That description
> of WebPage is not meant to imply anything about the relationship of those
> top-level objects... all that is saying is that if a relation is declared
> without an explicit subject, then the subject will be assumed to be the
> current WebPage.
>
> That said, we probably do need a mechanism for indicating the "primary
> entity" of a webpage when there is one.  Current clients make up their own
> heuristics for this, but I think it would be better to have an explicit way
> of stating that.
>
> -jason
>
>
> On Thu Apr 17 2014 at 10:41:47 AM, Jarno van Driel <jarno@quantumspork.nl>
> wrote:
>
>> I'm trying to understand semantic mechanisms better but am a bit confused
>> about schema.org/WebPage and I'd like to know how it works.
>>
>> Now it could well be I understand certain terminologies wrong, so please
>> bare with me and be so nice to correct me when needed.
>>
>> 1] The description of http://schema.org/WebPage says:
>> "Every web page is implicitly assumed to be declared to be of type
>> WebPage, so the various properties about that webpage, such as breadcrumb
>> may be used. We recommend explicit declaration if these properties are
>> specified, but if they are found outside of an itemscope, they will be
>> assumed to be about the page."
>>
>> code example:
>> <body itemscope itemtype="http://schema.org/WebPage">
>>   <!-- Content -->
>> </body>
>>
>> Now if the WebPage is the only entity is it then considered to be the
>> 'Subject', the 'Object' or both?
>>
>> 2] If the WebPage contains an entity, let's say a Product, without
>> specifying a property on the Product and I check this with Google's SDTT, I
>> see 2 'root' entities, since there is no property to chain the two
>> together. Yet I get the impression the Product gets treated as the
>> 'Object', since it's the Product that gets used for Rich snippet
>> extraction, and that therefore the WebPage is the 'Subject' :
>>
>> code example:
>> <body itemscope itemtype="http://schema.org/WebPage">
>>   <span itemprop="name">Page title</span>
>>
>>   <div itemscope itemtype="http://schema.org/Product">
>>     <span itemprop="name">Product name</span>
>>     <!-- Product properties -->
>>   </div>
>> </body>
>>
>> Now since "Every web page is implicitly assumed to be declared to be of
>> type WebPage" I was wondering if there also is a property that is
>> 'implicitly assumed to be declared' (something like @contains) on the first
>> entity that comes after it, like Product in this case, which indicates that
>> the Product is the 'Object'?
>>
>> And if not, than how does a parser 'know' which of the entities is the
>> 'Subject' and which is the 'Object', shouldn't there be a predicate for
>> this?
>>
>> 3] When a WebPage contains a bunch of 'root' entities, how does a parser
>> make sense of this, does the DOM have anything to do with this?
>>
>> <body itemscope itemtype="http://schema.org/WebPage">
>>   <span itemprop="name">Page title</span>
>>
>>   <div itemscope itemtype="http://schema.org/Product">
>>     <span itemprop="name">Product 1 name</span>
>>     <!-- Product properties -->
>>   </div>
>>
>>   <div itemscope itemtype="http://schema.org/Product">
>>     <span itemprop="name">Product 2 name</span>
>>     <!-- Product properties -->
>>   </div>
>>
>>   <div itemscope itemtype="http://schema.org/LocalBusiness">
>>     <span itemprop="name">Business name</span>
>>     <!-- Product properties -->
>>   </div>
>> </body>
>>
>> Now the above could be full of misunderstandings because I lack in
>> theoretical knowledge still, but that's exactly the thing I'm hoping to
>> change. Who can enlighten me?
>>
>>
>>
>>
>>
>>
Received on Thursday, 17 April 2014 18:16:11 UTC

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