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Re: URI fragments

From: Paolo Ciccarese <paolo.ciccarese@gmail.com>
Date: Thu, 4 Oct 2012 09:12:21 -0400
Message-ID: <CAFPX2kBH-4_2zVJKJnu7yK83s6n0cxT8d5ocGTOHKAuQAoP0WQ@mail.gmail.com>
To: Nick White <nick.white@durham.ac.uk>
Cc: public-openannotation@w3.org
Hi Nick,
the idea is that you can use the fragments URIs but not directly as they
are.

Given the current structure of the OA model we *recommend* to split source
and fragment for the reasons that are listed in the specs. In other words,
if you use a fragment URI directly that might work for you but we wanted to
make clear that, within this model, that would create problems in using
other features, querying, sharing and recording additional provenance info.

As for http://www.ietf.org/rfc/rfc2119.txt The adjective "RECOMMENDED",
mean that there may exist valid reasons in particular circumstances to
ignore a particular item, but the full implications must be understood and
carefully weighed before choosing a different course.

Therefore if you have
http://www.example.com/example.ogv#t=10,20
we recommend to brake it down:

<SpTarget1> a oa:SpecificResource ;
    oa:hasSelector <Selector1> ;
    oa:hasSource <http://www.example.com/example.ogv> .

  <Selector1> a oa:FragmentSelector ;
    rdf:value "t=10,20" .

And the Fragment URI may be reconstructed by concatenating the oa:hasSource
resource's URI, plus a '#', plus the value of the Fragment Selector. As OA
model is a format for exchange, the application consuming the annotation
dat is supposed to perform the operation when necessary.

Of course, I agree the above set of triples does not look as compact as
http://www.example.com/example.ogv#t=10,20 is. But in general terms, we
know that approach causes side effects.

Hope this helps,
Paolo



On Thu, Oct 4, 2012 at 7:00 AM, Nick White <nick.white@durham.ac.uk> wrote:

> Hi,
>
> I am very interested in the work OpenAnnotation is doing. It looks
> like it could be very useful indeed.
>
> In reading the spec, section 5.2.1 "Fragment Selector"
> <http://www.openannotation.org/spec/core/#SelectorFragment>, it
> recommends against using fragment URIs to identify segments.
>
> I don't really understand the rationale for this. The language
> used in the spec is not easy for me to follow. Please could somebody
> clarify the reasons for me?
>
> It seems to me (in my ignorance, no doubt) that standard URI
> fragment selectors are an obvious and good choice. I was planning to
> use RFC5147 to refer to sections of text, which is a nice, simple
> way of doing so. It's basic, but fine for my needs, and being human-
> readable and easily usable in other contexts has its advantages.
>
> Thanks for any guidance, and I look forward to exploring
> OpenAnnotation more.
>
> Nick White
>
>
>


-- 
Dr. Paolo Ciccarese
http://www.paolociccarese.info/
Biomedical Informatics Research & Development
Instructor of Neurology at Harvard Medical School
Assistant in Neuroscience at Mass General Hospital
+1-857-366-1524 (mobile)   +1-617-768-8744 (office)

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Received on Thursday, 4 October 2012 13:12:50 GMT

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