- From: Gregg Kellogg <gregg@greggkellogg.net>
- Date: Fri, 6 Jun 2014 10:22:49 -0700
- To: Markus Lanthaler <markus.lanthaler@gmx.net>
- Cc: public-hydra@w3.org
On Jun 6, 2014, at 9:51 AM, Markus Lanthaler <markus.lanthaler@gmx.net> wrote: > On Friday, June 06, 2014 10:22 AM, Ruben Verborgh wrote: >>> IME, a lot of people (outside the SemWeb community) find traversing > links in >>> the reverse direction "unnatural" and "hacky". >> >> But that's not what it is. >> We can't change the RDF model. > > I agree, nevertheless people get confused about this. Introducing a > mechanism to also support a direct forward link doesn't mean at all that we > are changing RDF. We are just giving more explicit information to the client > (yeah, it is redundant information but it might help some simpler clients). > > Side note: the "rev" attribute to express reverse links has been in HTML > from the very beginning. As it wasn't really used and often lead to errors, > it has been obsoleted in HTML5 [1]. > > >>> it indicates what kind of triples can be found in the collection. >> >> Agree. So a term like "is collection of" could also work? > > Sure, even though I personally don't like this specific term very much: > > /alice/friends isCollectionOf [ > subject /alice > property schema:knows > ] > > This looks a bit weird for me. If just naming things would be easier :-) It doesn't look particularly weird, IMO, but does bind it to collection, where we want to keep it more generic. IMO, hydra:manages is a good term, but we could consider something like hydra:ldFragment, which is really what it is, not that it conveys the specific purpose of the entity. I'd say just keep with hydra:manages. >> Nothing in the term description requires the word "manages". >> >> The case I'm trying to make here is: >> "manages" is a lot vaguer than (for instance) "is a collection of". >> There can be many ways in which one resource manages another, >> hence the thousand different semantics of Manager components in Java. > > Right. So, if we would like to describe that an HTTP LINK operation supports > the creation of certain links, how would we describe that? We would need to > introduce a separate property to do so, right? With "manages" we could > simply say > > xy a Operation > method LINK > manages [ > subject /alice > property schema:knows > ] > expects schema:Person > > It is a tradeoff, do we want to keep the vocabulary small at the cost of > vaguer names or do we prefer to have more explicit names at the cost of a > bigger vocabulary? I generally lean towards the former. > > >>> First of all, it should tell clients why they might or might not be >>> interested in a collection. We might decide to reuse it at a later point > to >>> describe operations in more detail. It could for instance also be used > to >>> indicate that an HTTP Link operation can be used to manage certain >>> subject/property pairs. >> >> But that's not aligned with what you wanted to express above: >> >>> it indicates what kind of triples can be found in the collection. > > Why not? Doesn't the information about "what kind of triples can be found in > the collection" help clients to decide "why they might or might not be > interested in a collection"? > > >> This reinforces my believe we're actually looking for :isCollectionOf >> of something similar. >> It's really those declarative semantics we need here, >> not the operational semantics. > > Does this imply that you would like to have a different property for the > operation I outlined above? > > > Summarized, I think we found a pattern for collections which everyone can > live with. AFAICT, there are three open issues: > > 1) Do we want to introduce something like hasCollection? +1 > 2) Should we rename "manages"? - 0.1 > 3) Should we reuse rdf:subject/predicate/object instead of introducing > hydra:subject/property/object (predicate or property?) -1: a manages block is not a reified statement, and I don't see how this aids the use case. Gregg > Have a nice weekend, > Markus > > > > [1] > http://www.w3.org/TR/2014/CR-html5-20140429/obsolete.html#non-conforming-fea > tures > > > -- > Markus Lanthaler > @markuslanthaler > >
Received on Friday, 6 June 2014 17:23:21 UTC