Re: representing hypermedia controls in RDF

sigh... copying to the list this time.

On Fri, Nov 22, 2013 at 1:10 PM, mike amundsen <mamund@yahoo.com> wrote:

> yep. In past writing/speaking I've drawn a line from James Gibson through
> Donald Norman and up to Roy Fielding[1]
>
>
> [1] http://amundsen.com/blog/archives/1109
>
> mamund
> +1.859.757.1449
> skype: mca.amundsen
> http://amundsen.com/blog/
> http://twitter.com/mamund
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> http://www.linkedin.com/in/mamund
>
>
> On Fri, Nov 22, 2013 at 12:40 PM, Pat Hayes <phayes@ihmc.us> wrote:
>
>>
>> On Nov 22, 2013, at 9:42 AM, mike amundsen <mamund@yahoo.com> wrote:
>>
>> > <snip>
>> > A browser for example doesn't render the string
>> http://example.com/343-224122 as a clickable link unless you mark it up
>> as one using the <a> tag.
>> > </snip>
>> >
>> > Yep, the A element is the thing that _affords_ clicking. it is the A
>> element which is the affordance.
>>
>> Just out of interest, as you using "affordance" in the same sense that it
>> is used in ecological pyschology? (
>> http://en.wikipedia.org/wiki/Affordance)
>>
>> Pat Hayes
>>
>> >
>> > Affordances don't just supply addresses, they supply information about
>> what you can _do_ with that address (navigate, transclude, send arguments,
>> write data, remove data, etc.). The appearance of a URL alone provides very
>> little affordance.
>> >
>> > For example:
>> > - http://example.com/xxxxx
>> > - http://example.com/yyyyy
>> > one of the two URLs points to a blog page to which the user can
>> navigate, the other points to a logo which should be displayed inline.
>> which is which?
>> >
>> > Now this:
>> > - <a href="...">blog</a>
>> > - <img href="..."  />
>> > one of the two URLs points to a blog page, the other points to a logo.
>> which is which?
>> >
>> > Note it is not the URL that provides the information (which is for
>> navigation, which is for transclusion), but the element in which the URL
>> appears. The element is the affordance. These are HTML affordances. There
>> are a couple more hypermedia affordances in HTML. Other message models
>> (media types) contain their own affordances.
>> >
>> > It is the appearance of affordances within the response representation
>> that is a key characteristic of hypermedia messages.
>> >
>> >
>> >
>> > mamund
>> > +1.859.757.1449
>> > skype: mca.amundsen
>> > http://amundsen.com/blog/
>> > http://twitter.com/mamund
>> > https://github.com/mamund
>> > http://www.linkedin.com/in/mamund
>> >
>> >
>> > On Fri, Nov 22, 2013 at 10:13 AM, Markus Lanthaler <
>> markus.lanthaler@gmx.net> wrote:
>> > Hi Martynas,
>> >
>> > On Friday, November 22, 2013 3:12 PM, Martynas Jusevičius wrote:
>> > > Markus,
>> > >
>> > > in the Linked Data context, what is the difference between
>> > > "identifier" and "hyperlink"? Last time I checked, URIs were opaque
>> > > and there was no such distinction.
>> >
>> > These things quickly turn into philosophical discussions but simply
>> speaking
>> > the difference lies in the expectations of a client. In XML for example,
>> > namespaces are just identifiers. There's no expectation that you can go
>> and
>> > dereference that namespace identifier (even though in most cases they
>> use
>> > HTTP URIs). The same is true about RDF. All URIs are just identifiers.
>> From
>> > an RDF point of view, there's no difference between isbn:343-224122 and
>> > http://example.com/343-224122. As you say, they are opaque.
>> >
>> > But if you build applications, it is important to distinguish between
>> > identifiers and hyperlinks. A browser for example doesn't render the
>> string
>> > http://example.com/343-224122 as a clickable link unless you mark it
>> up as
>> > one using the <a> tag.
>> >
>> > Linked Data advocates that all URIs are dereferenceable. But that's
>> > communicated out of band. Apart from JSON-LD, which states that URIs
>> SHOULD
>> > be dereferenceable, no other RDF media type makes such a statement.
>> Thus you
>> > need to use constructs such as hydra:Link and hydra:Resource to make the
>> > distinction explicit.
>> >
>> > Hope this helps. If not, let me know.
>> >
>> >
>> > --
>> > Markus Lanthaler
>> > @markuslanthaler
>> >
>> >
>> >
>>
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