Complexity of RDFa

Hi all

 

So following up on a discussion I had with Manu via Twitter I just want to
raise the following couple of points about my opinions on RDFa.

 

My main issue with RDFa is that like RDF/XML it lets you state the same
thing in a lot of different ways.  While this may be somewhat necessary when
the aim is to provide a format that can be embedded inside XHTML and HTML
which themselves have lots of different ways of expressing the same thing I
think it makes it difficult for developers and end users to decide how best
to do something.  Essentially I feel it's over complex in some ways - for
example there are about 7 different ways that the subject of a triple can be
set and the order & priority of these changes if there is an @rev or @rel on
the element.

 

In some respects from a developer standpoint (in terms of parsing) this
complexity is irrelevant, the rules are very clear and you can write a
parser relatively quickly that can extract the RDFa from HTML/XHTML.  But
from a developer standpoint in terms of embedding your RDF as RDFa inside
your markup it's a lot trickier to decide how best to do this because of the
many options on offer.

 

The other issue I raised is that while the RDF model is intended to encode
machine-readable data I'd much prefer to have a concrete syntax that is also
human readable e.g. Turtle.  While I can now after a year or so of staring
at it far too often read RDF/XML reasonably well I have yet to stare at
enough RDFa snippets to be able to do this and my feeling is that this is
far harder to do because you typically have all the extra non-RDFa stuff
associated with normal HTML/XHTML markup.  Manu's response to this is that
any non-trivial RDFa snippet typically does require you to shove it through
a parser to see what you've actually encoded which I fully appreciate and he
made the point that we use already web browsers to double-check JS, HTML,
CSS etc.  Yet if I write any JS, HTML, CSS etc I can easily see the intended
structure and function of the markup/code even if I have to run it through
my web browser to show up any typos, bugs, glitches etc whereas with RDFa I
don't feel I can do this in quite the same way.

 

Perhaps this may just be a case of not having worked with RDFa for long
enough to feel truly comfortable with it - what do other people in the
community think?

 

Rob Vesse

 

PhD Student

IAM Group

Bay 20, Room 4027, Building 32

Electronics & Computer Science

University of Southampton

SO17 1BJ