Re: mlw-lt-track-ISSUE-131: URI scheme used in NIF conversion [MLW-LT Standard Draft]

Hi all,

to keep things together for tracker and the planned PR transition 
request I am replying to Phil's
http://lists.w3.org/Archives/Public/public-multilingualweb-lt/2013Aug/0066.html
and Dave's mails
http://lists.w3.org/Archives/Public/public-multilingualweb-lt/2013Aug/0067.html
in this thread.

Phil is saying in above mail
"I like option 1. of registering the char fragment id."
My co-chair response is to this: we need to take into account that the 
process of registering the char fragment id is not clear at all. The 
guidelines that the RDF WG is citing
http://www.w3.org/TR/fragid-best-practices/
are *guidelines* - there is no idendification of clear steps etc., a 
timeline to expect etc. So with our plan to finalize ITS2 this year, I 
would advise against this option if there is no clear and "safe" 
estimation how long this would take.

Dave is saying in his mail

[
If the URL used in the RDF for the NIF string subclass does not actually
need the char 'attributes' because we have nif:beginIndex and
nif:endIndex then is the rest of the URL redundant as we have that
information also (sort-of) explicitly in nif:wasConvertedFrom? If so why
even attempt to encode this information in the URL of the String
instance - could we just use any otherwise meaningful unique identifier
right?

I only ask because that latter option might avoid any further confusion
over the NIF examples in the spec, e.g. the query string option might
still tempt the question of how its used, but there might be other NIF
related implications I'm not aware of.
]

Not a co-chair opinion, but my personal one: indeed, the NIF conversion 
itself and also the testing we use on top of it (validate.jar in github,
https://github.com/finnle/ITS-2.0-Testsuite/tree/master/its2.0/nif-conversion/sparqltests
provided by Sebastian) do not rely on using "char=" as part of the URI - 
and not at all on "#". Here is an example of converting a copy of a 
wikipedia page
http://sasakiatcf.com/felix/diverse/Biology
with this service
https://github.com/fsasaki/its20-extractor/tree/master/wikipedia-extractor
you can transform it to NIF  and have "char" with "#" or anything else, 
see e.g.

http://tinyurl.com/plhk9qz

That kind of prooves that the "#" in the URI is not relevant for the 
conversion at all.

Now, one suggestion behind the RDF WG proposal is probably "make sure 
that each URI resolves to something". With both solutions 1) and 2) we 
can achieve that. But with 2) it is actually up to the implementer what 
the URI resolves to: 2) says "The WG uses a different URI scheme, ", but 
the query part of an URI with parameters "&" can also be generated by 
above service. So if we use the URIs just as identifiers (as Dave 
suggested), without a new URI scheme, we still can reply to the "linked 
data" requirement of allowing to resolve them. It is just up to the 
implementers to realize that resolution.

best,

Felix

Am 28.08.13 18:10, schrieb MultilingualWeb-LT Working Group Issue Tracker:
> mlw-lt-track-ISSUE-131: URI scheme used in NIF conversion [MLW-LT Standard Draft]
>
> http://www.w3.org/International/multilingualweb/lt/track/issues/131
>
> Raised by: Felix Sasaki
> On product: MLW-LT Standard Draft
>
> Copied from
> http://lists.w3.org/Archives/Public/public-multilingualweb-lt/2013Aug/0057.html
>
> Felix,
>
> this is the official review of the RDF WG on the ITS Draft, more exactly the NIF conversion section[1]. The RDF WG discussed the issue and took a resolution on this response[2]
>
> The problem we see in the conversion algorithm is the URI-s that the algorithm generates, namely the URI-s of the form
>
> <http://example.com/exampledoc.html#char=0,29>
> <http://example.com/exampledoc.html#xpath(/html/body[1]/h2[1])>
>
> although it is quite obvious what these are for, we do sense a problem with these nevertheless. Indeed
>
> - RDF Concepts 1.1 Last Call document[3] refers to IRI-s: RFC3987[4]
> - IRI-s map to URI-s: RFC3986[5]
> - What RFC3986 says about fragments is:
>
> [[[
> The fragment's format and resolution is therefore dependent on the media type [RFC2046] of a potentially retrieved representation, even though such a retrieval is only performed if the URI is dereferenced.  If no such representation exists, then the semantics of the fragment are considered unknown and are effectively unconstrained.
> ]]]
>
> Looking at the URI-s above:
>
> - The 'char' fragment id is defined by rfc 5147[6], but is defined for text/plain only. ITS talks about XML and HTML, ie, talks about resources whose media types are definitely _not_ text/plain
> - The 'xpath' fragment id is fine for XML. But it is not defined for text/html
>
> In view of this, we do not feel comfortable with the choice of the mapping; the resulting RDF triples will not be entirely correct because these URI-s are not correct. Additionally, although that is not an RDF requirement per se, the URI-s are not dereferenceable (because they are incorrect) which is also in contradiction with Linked Data Principles which are also prevalent in the community.
>
> We do see two ways around this issue
>
> 1. The WG registers the 'char' fragment id-s (see also [7] for guidelines) through IETF for HTML and XML. (Actually, extending the usage of 'char' to XML/HTML would be generally very useful). Also, the WG registers 'xpath' for HTML (although we realize that this may be difficult because it might not be acceptable for the HTML WG which 'owns' the text/html media type)
>
> 2. The WG uses a different URI scheme, trying to avoid fragment ids. Something like:
>
> http://www.w3.org/its?resource=http://example.com/exampldoc.html&char=0,29
> http://www.w3.org/its?resource=http://example.com/exampldoc.html&xpath=/html/body[1]/h2[1]
>
> where, of course, the www.w3.org/its part can be some other URI and, ideally, would refer to a service returning something feasible and intelligent on the request there.
>
> However. We also recognize that the mapping in the ITS document is _not_ normative. As a consequence, the ITS WG is perfectly in its right to go ahead and not to follow the comments of the RDF Working Group. In other words, the ITS Working Group does not have to ask again for a formal approval of the RDF Working Group on any decision it may take (although I would be interested by the decision:-)
>
> I hope this was helpful to you
>
> Sincerely, in the name of the RDF Working Group
>
> Ivan Herman (staff contact for the RDF WG)
>
> P.S. Note that there are similar efforts elsewhere, like the string-range fragment id[8] or the work IDPF did for ebooks[9], but we recognize none of these offer an alternative.
>
>
> [1] http://www.w3.org/TR/2013/WD-its20-20130820/#conversion-to-nif
> [2] https://www.w3.org/2013/meeting/rdf-wg/2013-08-28#resolution_1
> [3] http://www.w3.org/TR/2013/WD-rdf11-concepts-20130723/
> [4] http://tools.ietf.org/html/rfc3987
> [5] http://tools.ietf.org/html/rfc3986
> [6] http://tools.ietf.org/html/rfc5147
> [7] http://www.w3.org/TR/fragid-best-practices/
>
>
>

Received on Friday, 30 August 2013 17:51:47 UTC