Re: Major overhaul of the RDFa primer

On Sep 9, 2011, at 18:33 , Stéphane Corlosquet wrote:

> Hi Ivan,
> 
> Great work. Minor comments below.
> 
> 
> 
> On Fri, Sep 9, 2011 at 11:03 AM, Ivan Herman <ivan@w3.org> wrote:
> Guys,
> 
> based on the comments of the other day, I have made a pretty major overhaul of the RDFa 1.1 primer, see
> 
> http://www.w3.org/2010/02/rdfa/sources/rdfa-primer/
> 
> The goal, if you remember, was to put the vocab feature to the fore, and push the prefix possibilities a little bit into the background. That is essentially what I did; however, this created a cascade of changes, it was not only a simple reshuffling of the paragraphs. Indeed, the previous version of the Primer was based on the Open Graph Protocol of Facebook. Of course, it would have been possible to turn that around with vocab but, as we know, Facebook only recognizes the prefixed version, ie, og:title and friends. I think it would be really bad to use this example with vocab, knowing that nobody would ever use that in practice because that is not what Facebook recognizes. This meant that I had to redo all the examples, and I used, primarily, the Dublin Core properties as a primary vocabulary. I also added a separate section on multiple vocabularies, where I introduce prefixes; to make that part of the message even stronger, I also added some SIOC terms to the example (ie, to have an example using many different vocabularies).
> 
> That's good, I think it illustrates well when prefixes are required (and when vocab alone is enough). Note that the first OGP example with full URIs is not something that will be parsed ok by Facebook afaik. Maybe you could swap og and dc in this particular example, so full URIs are never used for OGP (use full URIs for dc instead)?
>  

In this sense that would not work either, because they only understand prefixes and the first example uses vocab only...


> 
> As an independent issue, I have also added a separate section on the usage of @resource. The recent discussion around @itemref, and the examples given by Stéphane and Lin Clark on how @itemref is used in the Drupal+microdata version and, more importantly, how the very same example can be encoded in RDFa using @resource and @about shows that the @resource-@about pattern is very important in practice. Ie, having a separate section on that is really good, so I added one.
> 
> As I said, this meant a major reshuffle of sections, change of examples, diagrams, etc. In other words, all kinds of error prone operations. I would really appreciate if some of you guys read the text and listed the bugs, misspellings, etc, that are undoubtedly there...
> 
> *If* we have lists in RDFa, I think a separate section on them (in the advanced features) would be worth adding. There is nothing at the moment on datatypes; I am not sure it is really necessary but maybe it is... Other than that, I feel that the primer is in a pretty good shape (modulo the problems you guys may still find).
> 
> 
> s/licencing/licensing


Oops... Done

> 
> [[[
> A Blank Node: blank nodes are not identified by URL. Instead, many of them have an RDFa typeof attribute that identifies the type of data they represent. This approach—providing no name but adding a type—is particularly useful when listing a number of items on a page that have no permanent URL, e.g., calendar events, authors on an article, friends on a social networfk, etc. 
> ]]]
> 
> s/networfk/network

Oops again

> 
> I read this as an encouragement to using blank nodes. I think we should encourage the use of identifiers and only encourage blank nodes when appropriate. Earlier in the document, some advantages are given for using URIs as opposed to ambiguous tokens like 'title' or 'created'. I think the primer should follow this for data items too. Social networks is a good example where using or reusing URIs for people is good and prevents ambiguity (many social networds provide URIs for profiles, even if not all of them are typed foaf:Person). Or did you purposely leave out the @about to avoid opening the foaf:Person/foaf:Document can of worm, in other words to avoid people from asserting that homepages are foaf:Person's?

There is that. There is also the issue about typeof defined in a way that it *does* generate those blank nodes and, because it is one of the features that often bites when using RDFa, it is important to node it there.

Nevertheless: what I did was to remove that 'particularly useful' bit from the comment. I have also added an extra paragraph on the fact that real URIs should be the preferred practice. Does this sound better?


> 
> [[[
> Figure 9: Structrure of Alice’s Site:
> ]]]
> s/Structrure/Structure


And oops again...


> 
> Steph.
> 


Thanks a lot Stéphane!

Ivan

----
Ivan Herman, W3C Semantic Web Activity Lead
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Received on Friday, 9 September 2011 17:06:26 UTC