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Re: Turtle in HTML question/issue

From: Gavin Carothers <gavin@carothers.name>
Date: Tue, 15 Nov 2011 13:41:54 -0800
Message-ID: <CAPqY83wHDWJKsOAtmvnHn-_L4mthvb56MK9ruvXJnnh0LEnOBg@mail.gmail.com>
To: Ivan Herman <ivan@w3.org>
Cc: "Eric Prud'hommeaux" <eric@w3.org>, Manu Sporny <msporny@digitalbazaar.com>, W3C RDF WG <public-rdf-wg@w3.org>, Jeni Tennison <jeni@jenitennison.com>, Sandro Hawke <sandro@w3.org>
Please note the change in email address gavin@topquadrant.com is no
longer a working group member, gavin@carothers.name is ;)

On Tue, Nov 15, 2011 at 11:19 AM, Ivan Herman <ivan@w3.org> wrote:
>
> On 15 Nov 2011, at 19:36, Gavin Carothers <gavin@topquadrant.com> wrote:
>
> [snip]
>
>>
>>>
>>> However. I wonder whether it makes sense for the surrounding RDFa content to have some effect on the turtle portion. Namely:
>>>
>>> - base setting in HTML (which is also the base for the generated RDF from RDFa) would be a @base for the encoded turtle. AFAIK we discussed that at some point, but I have not found it in [1]
>>
>> There is a need for specific language. But I'm not sure that
>> supporting using the HTML base the best way to go. The UA would need
>> to support <base> @xml:base and the base URI DOM API in order to be
>> compliant with the HTML5 notion of base. And exactly how that
>> interacts with @base would also need to be defined. This would also do
>> some odd things to copy and paste safety.
>>
>>> - maybe more importantly: if RDFa sets a bunch of prefix declarations (and in RDFa there are even some defaults, eg, for rdf or foaf), I wonder whether those prefix declarations should not be valid as @prefix declarations in the embedded turtle. I think that would really be useful for HTML+RDFa authors.
>>
>> Allowing the use of RDFa prefix declarations which can come from
>> xmlns, prefix attributes, and vocab attributes would in my mind
>> needlessly complicate the consumption and authoring of Turtle <script>
>> fragments. Again it would greatly reduce copy and paste safety.
>>
>
> First of all, I would consider only xmlns and prefix or, possibly, prefix only. Not vocab, that does not define a prefix.

Okay time to go deeper into this issue. The prefixes defined in RDFa
are not the same as the prefixes defined in Turtle. RDFa prefixe
resolution uses CURIES and in Turtle PNames. The syntax is not
identical. Clearest case of that is in the Facebook Open graph
vocabularies which use :'s in the local part of the name which is not
allowed in Turtle. I'm not totally opposed to aligning Turtle with
RDFa, but others were as it breaks alignment with SPARQL which isn't a
great idea.

>
> I understand the issue of copy paste. On the other hand, if I author an RDFa file, where I define a load of prefixes, and then I have to repeat the whole thing again is also error prone and certainly a paini the neck. Ie, I am not convinced the balance is again the reusage of prefixes. The same holds for base, referring to the previous issue...

One thing this does to Turtle is create the notion of an initial
prefix map that may exist before parsing starts. This is a reasonably
large change to Turtle. A <script> Turtle document may not be a valid
Turtle document without the HTML it's in, not thrilled by that idea.
This might be simpler to solve with tooling that just reads an HTML
document and outputs the correct @prefix lines.

>
>>> - SVG already has a way to add RDF/XML as metadata, as well as the possibility to add RDFa statements[2]. More interestingly, it also has a script element[3]. I think the Turtle syntax should allow for the same style of turtle embedding for SVG, too.
>>
>> The script element (with the added CDATA directives) would work the
>> same way as it does in XHTML.
>
> Right. What I am saying is that the Turtle document should refer to SVG alongside HTML.

Okay, I'll take a stab at some text to that effect tonight.

>
>
>>
>>>
>>> B.t.w., I think it would be good to publish a Turtle draft soon with those features. This Turtle-in-HTML would be an important addition to the current approaches of embedding RDF data into HTML...
>>>
>>> Thoughts?
>>
>> I would like to publish a new draft before the of the month. Exactly
>> what is included in it should be decided by the RDF WG. (N-Triples?
>> Turtle in HTML? xsd datatypes?)
>>
>
> I think turtle in html is important and good, and I would be in favour keepig in.

So am I :D Just not sure about the rest of it.

>
> Ivan
>
>
>> --Gavin
>>
>>>
>>> Ivan
>>>
>>>
>>> [1] http://dvcs.w3.org/hg/rdf/raw-file/default/rdf-turtle/index.html#in-html
>>> [2] http://www.w3.org/TR/SVG11/metadata.html
>>> [3] http://www.w3.org/TR/SVG11/script.html#ScriptElement
>>>
>>> ----
>>> Ivan Herman, W3C Semantic Web Activity Lead
>>> Home: http://www.w3.org/People/Ivan/
>>> mobile: +31-641044153
>>> FOAF: http://www.ivan-herman.net/foaf.rdf
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>
Received on Tuesday, 15 November 2011 21:42:31 GMT

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