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Re: Consumer guidance

From: Jeni Tennison <jeni@jenitennison.com>
Date: Tue, 22 Nov 2011 21:48:28 +0000
Cc: HTML Data Task Force WG <public-html-data-tf@w3.org>
Message-Id: <E902C85D-AF1A-4A42-9886-6D32C53E2DB4@jenitennison.com>
To: Ivan Herman <ivan@w3.org>

On 22 Nov 2011, at 10:05, Ivan Herman wrote:
> I miss some other factors that may have to be listed as part of the publishing/consuming decision.
> - Are you bound to one vocabulary or more. If only one, I guess RDFa/md/mf provide a more or less equal environment in this respect; but if you are bound to several vocabularies (now or in future) within the content, eg, to combined it with Linked Data, RDFa is much more appropriate

Are you talking about for publishing or consuming?

For publishing, the page


talks about the mechanics of using multiple vocabularies. I'm not sure what to add there? Perhaps something more in the part in the page



  If your target consumers will all accept the same syntax, it is usually
  easiest to use that single syntax in your pages. However, microdata does
  not support multiple types for a single entity, so if your target 
  consumers expect different vocabularies to be used for the same entities 
  you may find it easier to mix syntaxes or use RDFa or microformats, which
  do support multiple vocabularies.

Would that address your concern?

On the consuming side, perhaps it's worth adding something like:

  While adopting existing vocabularies is generally a good idea, be aware
  that it can be hard for publishers to use multiple vocabularies to
  describe a single entity, particularly if they use microdata to do so.
  It will generally work best to consume a single base vocabulary on top
  of which you understand additional properties.

I don't know if that's along the lines you were thinking?

> - I am not sure you want to raise the datatype issue, but there are again differences there that may influence the publishing and consuming choices

OK, I think that probably comes under vocabulary design. As far as I can see, the only time the ability to annotate values with datatypes makes a difference is if the type of the value of a property cannot be inferred from the property and the syntax of the value. Personally, I've been convinced that vocabularies in which that's the case are hard to use and likely to lead to bad data.

I think that's a good thing to mention in the vocabulary design page. I'll have a go at some wording...

> - If you rely on javascripting together with the structured data, there are again differences: microformats, as far as I know (may be wrong!) does not have a dedicated API; microdata has that as part of its definition; RDFa has some drafts around but they are not on the same level of maturity as their counterpart in microdata. A somewhat similar issue is the access to the data in json.

Yes. The section on Tooling Considerations at


is meant to cover that, but of course it's hard to give general advice there both because we can't list all available tools and because the tooling landscape changes so rapidly.

But yes, it could do with being less mealy-mouthed. I'd welcome any suggested wording (or just edit the page).


Jeni Tennison
Received on Tuesday, 22 November 2011 21:48:56 UTC

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