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Re: Turtle in HTML question/issue

From: Ivan Herman <ivan@w3.org>
Date: Wed, 16 Nov 2011 09:11:50 +0100
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>
Message-Id: <A7CEC1E0-8CF3-492E-8E33-80620B1024C7@w3.org>
To: Gavin Carothers <gavin@carothers.name>

On Nov 15, 2011, at 22:41 , Gavin Carothers wrote:
[snip]

> 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.
> 

Sigh. You do have good arguments, although at present it is a pain to repeat all the prefix declarations. Ie, there would be no really smooth ways of using both turtle and RDFa in the same page, although I do see very legitimate usage for this (that is why I like it!). It has happened several times to me that the RDF I wanted to generate from an HTML file included a bunch of statements that are really not for display (this does happen with more complex vocabularies) and the current trick is to use a <div style="display:none> for this, and then encode things in a series of <span> which then resembles RDF/XML:-). Adding turtle in HTML is a very elegant way of solving this issue...

Ie: I am torn!

Ivan



>> 
>>>> - 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
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>> 


----
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 Wednesday, 16 November 2011 08:09:25 GMT

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