Hi Martin, 2009/6/29 Martin Hepp (UniBW) <[email protected]>: > Hi Tom: > >>Amen. Thank you for writing this. I completely agree. RDFa has some >>great use cases but (like any technology) has its limitations. Let's >>not oversell it. > > We seem to agree on the observation, but not on the conclusion. What I want > and suggest is using RDFa also for exchanging a bit more complex RDF models > / data by simply using a lot of div / span or whatever elements that > represent the RDF part in the SAME document BUT NOT too closely linked with > the presentation level. > > <body> > <h1>This is the car I want to sell</h1> > Actually, a pretty cool car, for only $1.000. Offer valid through July 31, > 2009 > > <span> > ... my whole RDF in RDFa > </span> > <body> > > The advantage of that would be that > > - you just have to maintain ONE file, > - data and metadata are close by, so the likelihood of being up to date > increases, and > - at the same time, the code does not get too messy. > - Also - no problems setting up the server (*). > - Easy to create on-line tools that generate RDFa snippets for simple > pasting. > - Yahoo and Google will most likely honor RDFa meta-data only. > > Also note that often the literal values will be in content attributes > anyway, because the string for the presentation is not suitable as meta-data > content anyway (e.g. dates, country codes,...) > > I think the approach sketched above would be a cheap and useful way of > publishing RDF meta-data. It could work with CMS / blogging software etc. > Imaging if we were able to allow eBay sellers to put GoodRelations meta-data > directly into the open XHTML part of their product description. > > The main problem with my proposal is that there is the risk that Google > considers this "cloaking" and may remove respective resources from their > index (Mark raised that issue). If that risk was confirmed, we would really > have a problem. Imagine me selling Semantic Web markup as a step beyond SEO > ... and the first consequence of following my advice is being removed from > the Google index. > > A second problem is that if the document contains nodes that have no > counterpart on the presentation level (e.g. intermediate nodes for holding > n-ary relations), then they will also not be dereferencable. The same holds > for URIs or nodes that are outside the scope of the actual RDFa / XHTML > document - I see no simple way of serving neither XHTML nor RDF content for > those.
These are exactly the reasons why I emphasise the limitations and ask that we don't oversell the capabilities of any technology, RDFa included. Tom.
