Re: How RFC 5988 Link Relation fits Linked Data?

On Tue, Nov 4, 2014 at 9:15 PM, Markus Lanthaler <markus.lanthaler@gmx.net>
wrote:

> Hi Pavlik,
>
> On 1 Nov 2014 at 19:19, ☮ elf Pavlik ☮ wrote:
> > I would like to ask for help with clarifying use of RFC 5988 Link
> > Relation in context of Linked Data.
>

In my reading, what RFC 5988 describes is are very similar to RDF triples,
with the following translation table:
- context IRI -> subject
- link relation -> predicate
- target IRI -> object

Some adjustments are necessary with target attributes (especially anchor
and rev), but by and large, this works well enough.

>
> > In Activity Streams 2.0, which very recently became WPWD, we currently
> find:
> >
> > * as:Link - Describes a link to a separate resource.
> >
> http://www.w3.org/TR/2014/WD-activitystreams-vocabulary-20141023/#dfn-l
> >   ink * as:rel - The RFC 5988 Link Relation associated with a Link.
> >
> http://www.w3.org/TR/2014/WD-activitystreams-vocabulary-20141023/#dfn-r
> >   el
> > With some examples of their use available in:
> > http://www.w3.org/TR/2014/WD-activitystreams-core-20141023/#link
>
> This is similar to a reified statement. The advantage of such a model is
> that you can describe the link itself. The downside is that it introduces
> an intermediary node that kind of "obfuscates" the direct relationship
> between two resources which may add complexity.
>

I'm not sure I agree with this reading of Activity Streams 2.0. Despite
their name, Link values are not, IMHO, reified links, but rather represent
the target object of the link. Consider for example:

     {
       "objectType": "application",
       "id": "http://example.org/application/123",
       "displayName": "My Application",
       "image": {
         "url": "http://example.org/application/123.png",
         "rel": "http://example.org/ns#screenshot",
         "mediaType": "image/png",
         "height": 640,
         "width": 480
       }
     }

the inner object represents the image, with mediaType, height and width
being properties of that image ;
the rel attribute is very special in this respect, as it is *not* an
attribute of the image, but rather an alternative predicate (more specific
than as:image) pointing from the outer object to the inner object.

NB: This feature of the AS syntax is, IMO, what makes it diverge most from
JSON-LD.

 best


> HTH,
> Markus
>
>
> --
> Markus Lanthaler
> @markuslanthaler
>
>
>
>
>