Re: Affordances wiki page

Erik,

I agree with you that RDF in itself does not provide affordances, and that
the fact that it uses URIs does not mean that those URIs are links (in the
hypermedia/REST sense).

I think, however, that (RDF + some built-in knowledge about a given
vocabulary) does provide affordances. For example, a client knowing what
foaf:depication means can use it to provide a better representation of the
depicted resource.

The goal of the LDP recommendation is to describe the built-in knowledge
that all LDP-client are expected to have about the ldp: vocabulary. And
this knowledge about the ldp: vocabulary should apply to *any* RDF graph
that the client encounters, regardless of the media-type it got it from
(Turtle, RDF/XML, RDFa...). So I disagree with you that we need a specific
media-type for LDP.

Of course, it would be good to provide the client with a hint of the
vocabularies it can expect to find in some RDF, even *before* parsing it.
This is where I think your profile proposal adds some value, as something
*orthogonal* to the media-type.

  pa


On Mon, Mar 4, 2013 at 9:50 AM, Wilde, Erik <Erik.Wilde@emc.com> wrote:

> hello john.
>
> On 2013-03-03 18:41 , "John Arwe" <johnarwe@us.ibm.com> wrote:
> >Erik, your HTML example strengthens the suspicion that had been growing
> >in me about your initial response (paraphrased playback) "the rows on
> >that page are not affordances", i.e. about how you were using the word.
> >As you're
> > using it, affordances are at a higher level of abstraction and what the
> >wiki page lists (or did, last I looked - on a plane now so unable to
> >check) are "just" spec options - things overtly relegated to
> >implementation choice.  Those would have an n:m relation
> > with affordances, by your definition.  Getting closer?
>
> do you have any idea where the http://www.w3.org/wiki/RdfAffordances page
> originates? i would argue that it contains some really misguided ideas,
> such as looking at the URIs in RDF as links. this mixes RDF's data model
> (which happens to be URI-based) with an entirely different issue, which is
> the question of how to represent hypermedia affordances (now i am using
> the term as i am used to it from the hypermedia/REST community), and once
> you start doing that, i don't think there's any way to get out of this
> initial conflation of concepts.
>
> for me, affordances are the critical parts of hypermedia formats that
> guide clients through the media type, allowing them choices of
> navigational paths while they are traversing the interlinked set of
> resources exposed as hypermedia. RDF doesn't have anything to contribute
> here as it doesn't have links. so affordances (again, in my view of the
> term) would be the kinds of things a hypermedia format such as LDP would
> add, saying "when you find this link in a representation, then you can
> follow it, and you have to interact in the following way when you follow
> it, and then you can expect the following thing to happen."
>
> cheers,
>
> dret.
>
>
>