Re: Question on qualified linking between two resources

I personally don't like the predicate-as-tag approach, as the predicate
does not individually tag both bodies. It seems strange to say
edm:similarTo is somehow about item/1

I would avoid trig:Graph as technology specific and not well used.  In
JSON-LD, there's the @graph construct that it would conflict with.

As per my message in the thread above, my approach would be to serialize
the statement to a body rather than including it as an extension point in
the annotation.  That way you create a future proof pattern (as you could
change what goes in the body to include more triples, or a different
syntax, or something other than RDF entirely) that a regular annotation
client can see and ignore, without requiring an additional context to add
the edm namespace.  Though you would need to include @prefix in the turtle.

HTH,

Rob


On Mon, Feb 8, 2016 at 5:53 AM, Hugo Manguinhas <
Hugo.Manguinhas@europeana.eu> wrote:

> Hi all,
>
> I am reviving this thread as I am still not completely confident with the
> proposal…
>
> .. .what do you think of the whole proposal?
> ... will it be alright to have as targets the two objects and the
> body(ies) conveying the relation (whether as a semantic tag, as an RDF
> statement or even as a text informally explaining the relation)?
>
> @Rob, all, what is you take on trig:Graph for the RDF statement? do you
> feel that it is necessary so that the "suggested" statement (relation)
> remains semantically decoupled from the Annotation, or do you feel that it
> should be part of it, like in your example/suggestion...
> ... btw, the issue that I see with the example below is the body is
> referencing the Resource and not the statement, so even if a trig:Graph is
> not used, the body would still need to be an rdf:Statement.
>
> I really appreciate all your feedback!
>
> Kind regards,
> Hugo
>
> ________________________________________
> From: Hugo Manguinhas
> Sent: 22 January 2016 13:41
> To: Ivan Herman; Robert Sanderson; Jacco van Osenbruggen
> Cc: W3C Public Annotation List; public-openannotation
> Subject: RE: Question on qualified linking between two resources
>
> Hi Rob, Jacco, Ivan, and all,
>
> Thank you all for your help!
>
> I must say I like @Jacco’s point on having a property (oa:hasPredicate or
> even rdf:property) to state the type of relation specially if this would
> allow client applications to search using it as a search criteria...
> however, I agree with Rob that it would better fit the web annotation
> principles to model it somehow within the body as it is where all
> information that the user wishes to convey about the target(s) is placed.
>
> about Rob’s first suggestion, I believe that pattern seems sufficient
> (@Rob, should the body btw be a trig:Graph as defined in OA?), however, I
> am concerned that non-RDF engines will not easily consume such data... and
> also it will require some effort to support a search scenario using both
> the predicate and the actual “domain” of the statement. Regarding the one
> that uses the turtle representation, It would again create an overhead for
> machines to interpret the data and it would make it even more difficult to
> search. I saw in Rob’s suggestion (last email) that the domain and range of
> the statement are both referred as targets which I found really interesting
> as it makes complete sense from the conceptual point of view and from a
> search perspective it allows for client applications to pull in and display
> annotations for both forward and backward links... great!
>
> … so first, i would propose to expand Rob’s first suggestion (without
> “@graph”) to add another target:
> {
>   "motivation": "linking",
>   "body": {
>     "@id": "http://data.europeana.eu/item/1",
>     "edm:isSimilarTo" : "http://data.europeana.eu/item/2"
>   },
>   "target": [ "http://data.europeana.eu/item/1", "
> http://data.europeana.eu/item/2" ]
> }
>
> … if it is relevant to promote the property and make it more explicit and
> thus easily searchable, I would propose to add an additional body with the
> property as a tag... allowing for basic client applications to process the
> data without understanding the RDF semantics:
> {
>   "motivation": "linking",
>   "body": [
>     {
>       "@id": "http://data.europeana.eu/item/1",
>       "edm:isSimilarTo" : "http://data.europeana.eu/item/2"
>     },
>     {
>       "@type": "SpecificResource",
>       "source": "http://www.europeana.eu/schemas/edm/isSimilarTo",
>       "role": "tagging"
>    }
>   ],
>   "target": [ "http://data.europeana.eu/item/1", "
> http://data.europeana.eu/item/2" ]
> }
>
> This last proposal would also allow to add yet another body with a
> possible comment from the user, expressing in a human readable form the
> relation between the two items.
>
> Would both proposals be alright? what do you think?
>
> Finally, one last question for @Rob, is it really important to state the
> bodies within a oa:Choice? couldn’t they just coexist together as separate
> bodies? or is it assumed that they would be interpret as a whole?
>
> Thanks again for all your comments and looking forward for your feedback!
>
> Best regards,
> Hugo
>
> ________________________________________
> From: Ivan Herman [ivan@w3.org]
> Sent: 20 January 2016 09:08
> To: Robert Sanderson; Jacco van Osenbruggen; Hugo Manguinhas
> Cc: W3C Public Annotation List; public-openannotation
> Subject: Re: Question on qualified linking between two resources
>
> Beyond the arguments Rob expressed below (which I agree with)... Jacco,
> you said:
>
> "specific triple is missing while it should be there (e.g. <
> data.europeana.eu/item/1> edm:isSimilarTo <data.europeana.eu/item/2>.)"
>
> Why "should be there"? The annotation vocabulary is not meant to cover all
> possible relationships among resources. If an (RDF aware) application wants
> to use and add such a triple the overall information set in its own
> namespace then it can do it without further ado. This can be done in
> Turtle; but for an RDF aware application the JSON encoding is in fact
> JSON-LD, ie, nothing else than RDF, ie, such triple can be added, too. I am
> not sure why such facilities should be built into the core beyond what RDF
> can already do. I guess I am missing something. Alternatively, defining a
> separate motivation that can be used for the Annotation as a whole seems to
> be perfectly adequate, too (sure, the client of the annotation would have
> to have its own logic to deduce that extra triple in that case).
>
> As Rob said, a general solution would probably require the use of named
> graphs (I do not even want to mention that stuff whose name begins with
> 'rei…'). If you are an RDF aware application then you can do that, using
> either the built-in facilities of JSON-LD, or TriX instead of Turtle. But I
> do not think this should be added to the WA model, it would utterly
> complicate things.
>
> Ivan
>
> P.S. See also my comment on another issue[1], more exactly paragraph
> starting by "The underlying issue…". This is highly relevant for this
> question, too.
>
>
> [1]
> https://github.com/w3c/web-annotation/issues/137#issuecomment-172872489
>
>
>
> > On 18 Jan 2016, at 20:32, Robert Sanderson <azaroth42@gmail.com> wrote:
> >
> >
> > The other option is to put it in the body... consider the following:
> >
> > Alice wants to say that the two resources she can see on screen (item/1,
> and item/2) are similar to each other.  She types into her client "These
> two items are very similar to each other".
> >
> > In shorthand:
> > {
> >   "body": {"text": "These two items are very similar to each other"},
> >   "target": ["item/1", "item/2"]
> > }
> >
> > Beatrice wants to say the same thing, but in a machine readable way as
> well as human readable.  She knows RDF and creates the appropriate triple.
> >
> > {
> >   "body": {
> >     "type": "Choice",
> >     "items": [
> >        {
> >           "text": "These two items are very similar to each other",
> >           "language": "en",
> >           "format": "text/plain"
> >        },
> >        {
> >           "text": "item/1 edm:similarTo item/2 .",
> >           "format": "text/turtle"
> >        }
> >     ]
> >   },
> >   "target": ["item/1", "item/2"]
> > }
> >
> > The pushback against adding the link to the predicate is for the
> following reasons:
> >
> >   *  We don't want to reinvent Named Graphs, RDF reification, or even
> just RDF triples.  And adding an explicit predicate to use between them is
> very close to that.  (Arguably it /is/ that)
> >
> >   *  When there isn't exactly one body and exactly one target, things
> get very confusing. Do all of the bodies have the same relationship to all
> of the targets? What if there's no body, then there's no subject?
> >
> >   * It's a specific technology choice to use RDF. It should also be open
> to assertions in other languages, if we're going to tackle it, and thus the
> body option above.
> >
> >   * There are already ways to do it, just that they're not pretty:
> >      1.  Add the triple into the graph (need a @context, gets lost in
> the mix)
> >      2.  Create new, explicit motivations (creates a complete parallel
> universe)
> >      3.  Add/Use a body with the full triple/graph/data  (needs to be
> parsed separately, repeats information)
> >
> >
> > Rob
> >
> >
> > On Mon, Jan 18, 2016 at 9:38 AM, Jacco van Ossenbruggen <
> Jacco.van.Ossenbruggen@cwi.nl> wrote:
> >
> > > On 18 Jan 2016, at 17:19, Robert Sanderson <azaroth42@gmail.com>
> wrote:
> > >
> > > There isn't a specific slot in the model for putting a predicate that
> should be associated between body and target resources.
> >
> > We’ve had this discussion year ago on the OA list, so I’m not going to
> repeat why I think the model deserves to have such a specific slot (e.g
> oa:hasPredicate or something similar to support existing applications that
> want to upgrade there triples that have been added using an annotation
> process to comply to our model).
> >
> > But I still think Hugo’s problem will be a frequent scenario: say Alice
> is a user familiar with RDF, and she knows that a specific triple is
> missing while it should be there (e.g. <data.europeana.eu/item/1>
> edm:isSimilarTo  <data.europeana.eu/item/2>.)
> > She sees an annotation API that allows adding annotations to body<
> data.europeana.eu/item/1>
> > She then quickly looks up in the model’s spec on how to express that
> single triple using the annotation model. It initially looks simple:
> subject is the body, object is the target, but … how to do the predicate?
> looking further ...
> > ... surprise, surprise, she cannot find it in the spec (so Alice thinks
> she has to be missing something very basic)
> >
> > So if adding the predicate slot to the model is not an option, I think
> we should at least help users facing this scenario by giving them some
> clear guidelines early in the specs on how to express annotations that have
> the same or similar intended semantics as a single simple RDF triple.
> >
> > Cheers, Jacco
> >
> >
> >
> >
> >
> >
> >
> > --
> > Rob Sanderson
> > Information Standards Advocate
> > Digital Library Systems and Services
> > Stanford, CA 94305
>
>
> ----
> Ivan Herman, W3C
> Digital Publishing Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> ORCID ID: http://orcid.org/0000-0003-0782-2704
>
>
>
>


-- 
Rob Sanderson
Information Standards Advocate
Digital Library Systems and Services
Stanford, CA 94305