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Re: RDF 1.1 Lite Issue # 2: property vs rel

From: Guha <guha@google.com>
Date: Sat, 22 Oct 2011 14:36:34 -0700
Message-ID: <CAPAGhv8NBZ41j1pEEx4zW+eaXMtD3ACzkkbOn9mMR_v-VS_wzw@mail.gmail.com>
To: Manu Sporny <msporny@digitalbazaar.com>
Cc: public-vocabs@w3.org
On Sat, Oct 22, 2011 at 1:49 PM, Manu Sporny <msporny@digitalbazaar.com>wrote:

> On 10/22/2011 01:38 PM, Guha wrote:
>> Google announced supported RDFa in 2009. One of the startling
>> discoveries we made was that the error rate (i.e., webmasters marking
>> up their pages to say X when the really meant to say Y) was about 3
>> times as much as it was for other formats (which include
>> microformats, sitemaps, Google shopping feeds, etc.). The error rate
>>  is/was so bad that we had resort to highly non-scalable techniques
>> like having humans look at the markup on each site to make sure it
>> said what the page said. More than 40% of the errors had to do with
>> the confusion between rel and property.
> That is startling. Could you please publish the data and analysis
> publicly so that those on this list may look at it and analyze it? We have
> a couple of approaches that we've discussed over the past 6+ years that
> could be applied if we knew exactly /how/ people were getting the markup
> wrong.

We will look into sharing what we can. We have on a number of occasions
shared aggregate data. It is not clear we are in a position to share
detailed information about other people's websites. You are of course
welcome to do the analysis yourself.

> I will also note that this particular data was never brought to the
> attention of the RDFa Working Group. When did you know about these
> errors? Why did you not share the data when you came across it? I ask
> because it would've impacted the design of RDFa 1.1 if you had shared
> this data with us at the time.

Manu, I think you are missing something here. We have communicated this
information, many times, in one-one meetings with Ben Adida and others as
we were working on developing microdata. At the end of the day, it was
negligence on the part of the folks designing RDFa 1.1 to not actively seek
input from some biggest consumers of RDFa.

>  It is important to note that this data is from a very large sample
>> (10s of millions of pages) taken from Schema.org's target audience:
>> webmasters of sites that are by and large not about technical stuff.
> A list of URLs would be great along with a technical analysis of all of
> those URLs. Specifically, the following data would be very helpful:

Google DOES NOT provide lists of URLs to anyone. You are welcome to go
crawl the web.

> * How frequent was the use of @rel vs. the use of @property?

> * When @rel was used, was it used in chaining or was it used to
>  simply refer to an external resource?

We don't recommend chaining. Almost no one producing markup with rich
snippets uses external resources.

> * In the Microformats and Creative Commons cases
>  (rel="license", rel="tag", etc.) did people get @rel wrong?

You should ask them.

> * How frequently does @rel and @property exist on the same element?

In the vocabulary we specified, never.

> * How frequently is @property used when @rel should have been used
>  instead?

Don't have the numbers, but it was pretty random. You have to understand
that at anything more than a few percent error rate, the data becomes
largely unusable in scale.

> * How frequently is @rel used when @property should have been used
>  instead?

I will look into doing this analysis, but am not sure when we will be able
to get around to this.

> Answering these questions will help us understand how the spec should
> change.
>  We really don't want to get into whether there is a distinction
>> between rel and property at a theoretical level.
> Who is "we" in this case? The RDFa WG does not want to get into a
> theoretical debate either. We care about authors easily generating good,
> valid data.

We = Google, Schema.org.

>  But the bottom line remains that as long as
>> the error rate in RDFa usage does not go down dramatically, it is not
>> a viable option for us.
> Who is "us" in this case?

Us = Google, Schema.org

>  The current proposal takes a step in the
>> right direction, but several big issues, like the removal of the
>> distinction between rel and property still need to be addressed.
> Could you please detail every one of those "big issues"?
> We are doing it. Jason brought up the other issue.

> -- manu
> --
> Manu Sporny (skype: msporny, twitter: manusporny)
> Founder/CEO - Digital Bazaar, Inc.
> blog: Standardizing Payment Links - Why Online Tipping has Failed
> http://manu.sporny.org/2011/**payment-links/<http://manu.sporny.org/2011/payment-links/>
Received on Saturday, 22 October 2011 21:37:02 UTC

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