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RE: Rethinking @src in the context of chaining rules

From: Hausenblas, Michael <michael.hausenblas@joanneum.at>
Date: Wed, 9 Jan 2008 12:10:47 +0100
Message-ID: <768DACDC356ED04EA1F1130F97D298520144A47D@RZJC2EX.jr1.local>
To: "Ivan Herman" <ivan@w3.org>
Cc: "RDFa" <public-rdf-in-xhtml-tf@w3.org>, "Manu Sporny" <msporny@digitalbazaar.com>


Ivan,

>(B.t.w.: shouldn't all these cases end up in the test series? I think 
>they should, because they reveal exactly those edge cases that might 
>shake an implementation.)

Sure. Thanks for pointing that out!
I'll add them to the Test Suite after our tomorrow's discussion ...

Cheers,
	Michael

----------------------------------------------------------
 Michael Hausenblas, MSc.
 Institute of Information Systems & Information Management
 JOANNEUM RESEARCH Forschungsgesellschaft mbH
  
 http://www.joanneum.at/iis/
----------------------------------------------------------
 

>-----Original Message-----
>From: public-rdf-in-xhtml-tf-request@w3.org 
>[mailto:public-rdf-in-xhtml-tf-request@w3.org] On Behalf Of Ivan Herman
>Sent: Wednesday, January 09, 2008 11:26 AM
>To: Manu Sporny
>Cc: RDFa
>Subject: Re: Rethinking @src in the context of chaining rules
>
>Hi Manu
>
>Yet another Manu test series:-) Thanks for these!
>
>(B.t.w.: shouldn't all these cases end up in the test series? I think 
>they should, because they reveal exactly those edge cases that might 
>shake an implementation.)
>
>Manu Sporny wrote:
>> Mark Birbeck wrote:
>> 
>> That assumes that the 'current item' is something other than 
>the image,
>> and is defined elsewhere, like so:
>> 
>> ------------------------ BIM Approach -------------------------------
>
>:-) I like the name:-)
>
>> <span about="#current-item" rel="foaf:img">
>>    ...
>>    <img src="current-item.jpg" />
>>    ...
>> </span>
>> ------------------------ Mark Approach 
>-------------------------------
>> <span about="#current-item">
>>    ...
>>    <img rel="foaf:img" src="current-item.jpg" />
>>    ...
>> </span>
>> ----------
>> <#current-item> foaf:img <current-item.jpg> .
>> 
>-----------------------------------------------------------------------
>> 
>
>To be precise: as far as I can see the first would work with Mark's 
>approach, too.
>
>
>> If an image is floating on a page, by itself, then we can't 
>link it like
>> we did above:
>> 
>> ------------------------ BIM Approach -------------------------------
>> <img src="current-item.jpg" rev="foaf:img" resource="#current-item"/>
>> ------------------------ Mark Approach 
>-------------------------------
>> <img about="#current-item" rel="foaf:img" src="current-item.jpg" />
>> ----------
>> <#current-item> foaf:img <current-item.jpg> .
>> 
>-----------------------------------------------------------------------
>> 
>
>That is correct.
>
>> or you could do like it like this (Note how nice Mark's markup looks,
>> the BIM markup looks wierd):
>> 
>> ------------------------ BIM Approach -------------------------------
>> <span about="#current-item">
>>    <span property="dc:title">A Picture of Me</span>
>>    <span property="dc:name">Me</span>
>>    <img src="current-item.jpg" rev="foaf:img" 
>resource="#current-item"/>
>> </span>
>> ------------------------ Mark Approach 
>-------------------------------
>> <span about="#current-item">
>>    <span property="dc:title">A Picture of Me</span>
>>    <span property="dc:name">Me</span>
>>    <img rel="foaf:img" src="current-item.jpg" />
>> </span>
>> ----------
>> <#current-item> dc:title "A Picture of Me" .
>> <#current-item> dc:name "Me" .
>> <#current-item> foaf:img <current-item.jpg> .
>> 
>-----------------------------------------------------------------------
>> 
>
>It is correct and I _do_ agree that the BIM approach looks a 
>bit weird. 
>Having said that (and I said that before): for _any_ RDFa 
>constructions 
>there will be use cases where, well, RDFa will look weird (witness the 
>problems raised by DanBri in another thread). We cannot win 
>all battles:-)
>
>> The important one, though, is how we apply rdf:type using 
>@instanceof:
>> 
>
>Yeah, that is the one that started a whole thread of discussions...
>
>> ------------------------ BIM Approach -------------------------------
>> <span about="#current-item">
>>    <span property="dc:title">A Picture of Me</span>
>>    <span property="dc:name">Me</span>
>>    <img src="current-item.jpg" instanceof="foaf:Image" rev="foaf:img"
>>         resource="#current-item"/>
>> </span>
>> ------------------------ Mark Approach 
>-------------------------------
>> <span about="#current-item">
>>    <span property="dc:title">A Picture of Me</span>
>>    <span property="dc:name">Me</span>
>>    <img rel="foaf:img" instanceof="foaf:Image" 
>src="current-item.jpg" />
>> </span>
>> ----------
>> <#current-item> dc:title "A Picture of Me" .
>> <#current-item> dc:name "Me" .
>> <#current-item> foaf:img <current-item.jpg> .
>> <current-item.jpg> rdf:type foaf:Image .
>> 
>-----------------------------------------------------------------------
>> 
>
>Well... I believe that is not the case in Mark's approach. 
>There are two 
>cases: either we look at
>
>http://www.w3.org/MarkUp/2008/ED-rdfa-syntax-20080103/
>
>as it stands now, or include a change I actually proposed in
>
>http://www.w3.org/mid/477E148C.3090009@w3.org
>
>Let us analyse them separately.
>
>1. In the _current_, documented approach the [new subject] in 
><img> will 
>be set to a new BNode by virtue of @instanceof, which has a higher 
>priority than @src. Ie, we would get a
>
>[] a foaf:Image;
>    foaf:img <current-item.jpg> .
>
>2. However, I think Mark also agreed with my analysis that @src should 
>move up the hierarchy. So look at
>
>http://www.w3.org/MarkUp/2008/ED-rdfa-syntax-20080103/
>
>with the difference that in step 2/3 @src handling must appear right 
>after @about. That  means that [new subject] will be set to 
><current-item.jpg>. That will then be used for typing, ie, we will 
>indeed get
>
><current-item.jpg> a foaf:Image .
>
>However,  because @src is also kept to play a similar role to 
>@resource/@href (in step 5 of the processing rules), @src is also used 
>to establish the value of [current object resource], we will also get 
>the weird triple:
>
><current-item.jpg> foaf:img <current-item.jpg>.
>
>Unless I misread the syntax document, that case is definitely 
>problematic...
>
>A way to amend that in Mark's model would be the extra rule somewhere 
>which says that if @resource, @href, or @src is used to set 
>the value of 
>[new subject] then it must be taken of the equation. But, well, what 
>this would mean is that <img> will end up with a hanging rel, namely
>
><current-item.jpg> foaf:img ??? .
>
>but this hanging rel will be never resolved, because <img> 
>does not have 
>any children.
>
>Indeed, the BIM version, though a bit weird due to the presence of 
>@resource, works, because @src is taken out of the process in setting 
>the [current object resource] (not in the current syntax 
>document but, I 
>believe, the way it should be in the BIM model).
>
>Ivan
>
>P.S. (I _hate_ to say that, but this was always my use case on 
>introducing @trel and @trev instead of a single @instanceof:-(. It is 
>indeed the presence and the behaviour of @instanceof that messes up 
>things here. However, the current BIM model with the @src behaviour 
>seems to be a fair compromise after all...)
>
>> Does that seem to be everybody's understanding of the differences
>> between BIM/Mark with regards to @src?
>> 
>> -- manu
>> 
>
>-- 
>
>Ivan Herman, W3C Semantic Web Activity Lead
>Home: http://www.w3.org/People/Ivan/
>PGP Key: http://www.ivan-herman.net/pgpkey.html
>FOAF: http://www.ivan-herman.net/foaf.rdf
>
Received on Wednesday, 9 January 2008 11:11:18 GMT

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