Re: Selectors as URIs?

On Mon, Apr 13, 2015 at 10:07 AM, Ivan Herman <ivan@w3.org> wrote:

> Hm. The problem is that there is a use case here that we may have to
> accommodate somehow.
> At the moment, if you take an Ebook, and you want to have a URI
> identifying a specific position within a specific chapter of a book, what
> you can use something like:
>
>
> http://www.example.org/book#epubcfi(/6/4[chap01ref]!/4[body01]/10[para05]/3:10)


Sure, because the Epub media type registration defines the meaning of
fragment section of URIs where Epub is a representation that can be
retrieved.
We can't legitimately just add #oa:Selector(...) to the end of the URI
instead.


epubcfi works, and is used, but it has its drawbacks (let me not go into
> all the details). One drawback is that what it offers as anchoring
> possibility though powerful) is way less flexible than the selector model,
> primarily the range selectors. The conceptual model behind those would
> become useful, as an alternative to something like epubcfi, if those
> structures could be used as fragments.


Agreed, and the same applies for every other media type as well.


Maybe we have to restrict its usage and define it only for specific media
> types (text, etc) to avoid the issues in your example on genetic sequences
> or full blown graphics. But believe something like that would be very
> useful and, for some communities, necessary.
>

The point from 3986 (and related) is that we _cannot_ define it for
specific media types unless we control them.  It's summarized in the first
bullet in the annotation spec I linked to.
For example, the meaning of a fragment on a plain text document is defined
by 5147: https://tools.ietf.org/html/rfc5147

So we can't just say that people should use #oa:Selector(...) with a plain
text document (or any other format) :(

Rob




> (b.t.w., I am not sure I understand your comment on RFC3986)
> [1] http://www.idpf.org/epub/linking/cfi/epub-cfi.html
>
> > On 13 Apr 2015, at 18:28 , Robert Sanderson <azaroth42@gmail.com> wrote:
> >
> >
> > We discussed fragments in the community group at length.
> >
> > The concerns about the approach are documented here:
> >     http://www.w3.org/TR/annotation-model/#fragment-uris
> >
> > These boil down to the fact that as you get more sophisticated
> selections the URI becomes unbearably long.
> > Consider serializing an entire SVG document into the URI to specify a
> non rectangular area. Or selecting the previous and following 1024 Gs Cs As
> and Ts to select a range of text in a genetic sequence.
> >
> > My personal position is that selectors should not be turned into
> fragments, because (especially) that would break the rules of fragment
> identifiers as laid out in RFC 3986:
> >
> > The semantics of a fragment identifier are defined by the set of
> representations that might result from a retrieval action on the primary
> resource.
> > As further discussed by JeniT here:
> >     http://www.w3.org/TR/fragid-best-practices/
> >
> > Basically, unless there's a new text/HTML RFC that allows us to do it,
> we can't arbitrarily shove the description of the segment into its identity.
> >
> > Rob
> >
> >
> > On Mon, Apr 13, 2015 at 9:10 AM, Ivan Herman <ivan@w3.org> wrote:
> > (Although this may not be immediately relevant to the Working Group
> right now, I think the question *may* become relevant, hence my copy to it…)
> >
> > Rob, Paolo,
> >
> > a question came up at the Digital Publishing IG today. The IG is looking
> at general fragment identifiers for the purpose of identifying portions
> within a digital document (typically EPUB, but also some future versions of
> it). The Selector structure of the OA obviously gives a great model for
> various types of anchors, mainly when combined with other, existing
> fragment id definitions.
> >
> > However, at present, the selectors are defined in terms of RDF
> resources; to take an example from the spec, it says, for example
> >
> > selector": {
> >       "@id": "http://example.org/selector1",
> >       "@type": "oa:DataPositionSelector",
> >       "start": 4096,
> >       "end": 4104
> > }
> >
> > To be usable for a fragment identification, this structure should be
> turned into some sort of a, well, URI fragment. I mean, it is probably
> relatively easy to do this, something like
> >
> >
> http://www.example.org/#selector(type=DataPositionSelector,start=4096,end=4104)
> >
> > would do it but, of course, the ideal would be if that type of fragment
> format would be defined at one place.
> >
> > The question is: has this ever been discussed previously on the OA
> model? If it hasn't been done, should it be done? If it should be done,
> should it be done by this WG, or some other group?
> >
> > Thanks
> >
> > Ivan
> >
> >
> > ----
> > Ivan Herman, W3C
> > Digital Publishing Activity 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
>
>
> ----
> Ivan Herman, W3C
> Digital Publishing Activity 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