W3C home > Mailing lists > Public > public-vocabs@w3.org > January 2013

Re: Should we adopt SKOS?

From: Martin Hepp <martin.hepp@ebusiness-unibw.org>
Date: Sat, 12 Jan 2013 10:00:20 +0100
Cc: Mike Bergman <mike@mkbergman.com>, Richard Wallis <richard.wallis@oclc.org>
Message-Id: <7E54FCE9-839F-413D-AAD7-BEBBD78B60E0@ebusiness-unibw.org>
To: "public-vocabs@w3.org Org" <public-vocabs@w3.org>
Dear all:

A few points from my perspective:

1. I agree that the process employed for the integration of the LRMI and GoodRelations can only work for a very small set of additional vocabularies. This is not a role model for arbitrary extensions, as Mike correctly states.
Already now, it is very difficult to track all potential clashes and conceptual misfits between schema.org and extension proposals from different communities, and that challenge will grow.

In the case of GoodRelations, the integration worked pretty well because
- the number of people involved was very small and
- GoodRelations and schema.org are both inspired by compatible basic conceptual distinctions.

Still, I can say that the integration of these few (ca. 28) additional types was very difficult, for lack of tooling and sheer complexity of the task, and it took us 13 months to get it done. It was like writing business software in Assembler language. However, we had the advantage of being outside any constraints from more formal standardization bodies; decisions we thought were reasonable could just be made in a "benevolent dictator style". In an open forum, the whole integration process would never have worked.

As a magic limit, I think that schema.org should never ever grow beyond 500 types.

2. We need a clear, shared agreement on what schema.org is and isn't. IMO, we should regard it as the central registry of types and properties that *typical Web masters* are encouraged to expose to *mainstream consumers* of such data, in Microdata or RDFa syntax. That is also in line with the self-characterization on the schema.org site.

All the other opportunities and challenges towards a Web of Linked Data should, IMHO, be dealt with *outside of schema.org*. We *may* need to enhance the extension mechanisms of schema.org for that, but I actually think that the current components like
- the additionalType property, 
- the external enumerations proposal,
- the schema.org extension mechanism for subtypes, and
- the generic extension mechanisms provided by RDFa 

already allow for most of what is needed.

The best that the Semantic Web community can hope for is that "leading edge" (BBC, BestBuy, NYT, Volkswagen, ...) sites will employ recipes that 

- combine schema.org in RDFa with additional data expressed in additional vocabularies, and that 
- in a way that validates for the search engines and provides and exposes additional data for future Semantic Web applications.

My current fear, however, is that people in the Semantic Web / Linked Data community hope they can use schema.org to push the whole vision or their personal work ("If I can get my XYZ ontology into schema.org, then the Semantic Web for the ABC domain will become a reality") into the wild. But that is bogus, since you try to fool Web masters to adopt something with the Google/Bing/Yahoo/Yandex SEO bait while pursuing a different agenda; and that will not work for long.

The research communities should be fair to acknowledge that schema.org was necessary because they failed to provide a basic set of type and property definitions for the most relevant domains in more than a decade.

3. Defining and defending consensus regarding the scope of schema.org will also help shield this forum from becoming a platform for wild discussions on semantics, the universe, and everything related to humans, aliens, and computers.

For foundational discussions on ontologies, the ontolog forum is the best choice. For Semantic Web and Linked Data topics, the respective W3C mailing lists are appropriate.

This list should, IMHO, really just be about 

a) concrete extensions of schema.org for certain domains or usage ("we need an additional property for type XYZ for the following reasons") and
b) issues with the current extension mechanisms or concrete proposals on how to enhance them, 

but again this only within the scope of "schema.org as the central registry of types and properties that typical Web masters are encouraged to expose to mainstream consumers of such data".



On Jan 11, 2013, at 10:56 AM, Richard Wallis wrote:

> Hi Mike,
> I think 1) is more pragmatic than you describe.  
> The core motivation for many is to have a way to describe their ‘things’ on the web using vocabulary types and properties that ‘the search engines’ will commit over time to recognising.  They want their things to be discoverable.  Using, or linking to resources described using, types & properties not recognised by the search engines will have little or no benefit towards that end.
> So starting with the Schema vocabulary ‘as it is’ trying to describe resources (sufficiently to aid their discovery), as we are in the bibliographic domain, it is clear there are a few gaps.  Some of those gaps are roughly equivalent to existent vocabularies, such as GoodRelations in ecommerce and in this case SKOS.  Hence the recommendation to adopt those vocabularies wholesale as needed.
> This does raise the issue of keeping in step with those vocabularies as they evolve.  I suspect that would be very difficult to do in a satisfactory way.  I believe the best we could do is to adopt (copy) the vocabulary at a moment in time into Schema and follow the extension proposal process for any changes – that is the only way the Schema backers could be expected to add them to the set that they will commit to recognising over time.
> Unfortunately this is where your attractive proposal for external namespace recognition would be difficult to implement/support – the only way to be sure that the search engines will commit to recognise something is that it is in the Schema namespace.
> Having said all that, I do recognise that a spin off benefit of the Schema initiative is the creation of a broadly recognised general purpose vocabulary for describing most things.  Will this be good enough or detailed enough for most domains to describe their resources for their own internal purposes – probably not. It never will be for the Library domain!
> As you will probably agree, Schema should not be viewed as the potential vocabulary to rule them all.  It is however becoming the de facto vocabulary you use to supplement your [domain’s] vocabularies of choice to make them discoverable by others.
> I agree with your concerns in 2) - we should not lose sight of the broad general purpose of the initiative and the goal of delivering something simple to help people mark up their data so the search engines can discover them.
> ~Richard.
> On 11/01/2013 04:50, "Mike Bergman" <mike@mkbergman.com> wrote:
>> Hi All,
>> I have a recommendation on the SKOS issue, if you will bear with me, but
>> the length of this inherited thread and its esoterica, I think, affirm
>> two observations:
>> 1) since the Good Relations adoption, there is a desire (precedent) to
>> want to find additional vocabularies that can be sanctioned by
>> schema.org's market position
>> 2) schema.org risks becoming the new forum for all sorts of semantic
>> folly and discussion.
>> I think both of these are a mistake.
>> As for 1), I can appreciate that Martin has worked the system well
>> enough to get his vocabulary accepted. It is a good vocabulary, and
>> Martin is a diligent advocate. But, frankly, I don't think this is a
>> model we want to see perpetuated. There are multiple realms that
>> conceivably deal with important dimensions of the "schema" scope; do we
>> seriously think it is the role of this forum to find those encompassing
>> descriptions?
>> Vocabulary acceptance is ultimately, I think, a market position, and not
>> any role or responsibility of schema.org.
>> The *sponsors* of schema.org, however, do have what amounts to much
>> market clout. If they like something, they will adopt it; if not, they
>> won't. The choices they make as players in making schema.org stuff
>> prominent or not will (in part) determine their own market performance.
>> I accept this, and whatever this forum does, it has no ultimate bearing
>> on these sponsors' market decisions. This forum is not the W3C (and even
>> the W3C making such determinations has little bearing on this market).
>> I also firmly believe that vocabulary extensions from concepts to
>> products to whatever should be accommodated for within a schema.org
>> framework. My issue is solely whether any single extension warrants
>> sanction. Extension mechanisms, yes; specific vocabularies, no.
>> As for 2), I think that is just a natural outcome of looking to
>> schema.org as some kind of "answer" to what used to be known as the
>> "chicken-and-egg dilemma" for the semantic Web. The best thing about
>> schema.org is that it is a pragmatic forum to discuss prominent types of
>> things and their attributes.
>> My advice is to try to keep schema.org as a relatively pure location for
>> important value:pair discussions. We'll get to the big stuff -- and
>> perhaps even schema.org will be in part one vehicle for doing so --
>> by-and-by, but this is a forum for *market importance* not theory.
>> As for the SKOS stuff, we (Structured Dynamics) use it much. But the
>> premise of the adoption into schema.org fits into that same
>> dysfunctionality I noted above: trying to make schema.org an umbrella
>> for sanctioned subsidiary vocabularies. I believe this to be a Bad Idea.
>> My simple suggestion is to move "about" to become a property of Thing
>> and not CreativeWorks (which, after reflection, is a placement that is
>> silly). Then, with an extension mechanism that recognizes an external
>> namespace (say, gr: or umbel: or dc:) enable that (or perhaps, many
>> other schema: properties) to extend the umbrella.
>> As for SKOS, I think it is generally orthogonal to a schema.org
>> specification. Like any vocabulary on the Web, map to the concepts that
>> make sense for you. If "about" with namespace recognition were added to
>> schema.org, there would be no further questions about what to do with
>> SKOS or any other Web vocabulary.
>>         schema.org != semantic web
>> Thanks, Mike
>> --
>> __________________________________________
>> Michael K. Bergman
>> CEO  Structured Dynamics LLC
>> 319.621.5225
>> skype:michaelkbergman
>> http://structureddynamics.com
>> http://mkbergman.com
>> http://www.linkedin.com/in/mkbergman
>> __________________________________________

martin hepp
e-business & web science research group
universitaet der bundeswehr muenchen

e-mail:  hepp@ebusiness-unibw.org
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         http://www.heppnetz.de/ (personal)
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Received on Saturday, 12 January 2013 09:00:48 UTC

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