Re: Selectors as URIs?

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)

which identifies a position within a paragraph within a chapter of the book inside an EPUB package. It uses the epubcfi[1] specification of IDPF, which specifies an EPUB specific fragment ID.

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. 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.

Cheers

Ivan

(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