Re: LDPR binaries in spec

Hi Henry,

On Dec 19, 2012, at 05:45, Henry Story <henry.story@bblfish.net> wrote:

> There are a few paragraphs in the current spec ( http://www.w3.org/2012/ldp/hg/ldp.html ) 
> which seem to need a bit of clarification, relating to ISSUE-15 probably. I am just noting
> it here, as I am thinking about this right now, and noticed these.
> It is also related to use cases 4.8 and 4.8.1 of the UCR
> http://www.w3.org/2012/ldp/hg/ldp-ucr.html#uc-manage_media_resources
> 
> 
> Definition:
> [[
> Linked Data Platform Resource (LDPR)
> HTTP resource that conforms to the simple lifecycle patterns and conventions in this document.
> ]]
> 
> So presumably resources that can be created in a collection and that get deleted 
> when a collection gets deleted. If we add images to a collection, are they then LDPRs?


I think the intent is for LDPRs to be RDF resources and non-LDPRs to be supporting binaries, such as images.  I agree the spec text needs to change to make that obvious.

I suggest changing the spec text to support the notion that both LDPRs and non-LDPRs may be created in a collection and deleted when a collection gets deleted.


> 
> [[
> 4.1.3 LDPR servers may host a mixture of LDPRs and non-LDPRs. For example, it is common for LDPR servers to need to host binary or text resources that do not have useful RDF representations.
> ]]
> 
> This seems to suggest that LDPRs cannot be binaries.
> 
> [[
> 4.2.2 LDPR servers must provide an text/turtle representation of the requested LDPR.
> ]]
> 
> If one were to create a picture, would this say that one MUST return turtle for it by default?
> That would not be completely silly it could be a representation of the picture that said
> something like:
> 
> ------------------------------
> @prefix iana: <http://www.iana.org/assignments/relation/> .
> @prefifx foaf <http://xmlns.com/foaf/0.1/> .
> @prefix awol: <http://bblfish.net/work/atom-owl/2006-06-06/#> .
> 
>  <> a foaf:Picture;
>    foaf:depicts joe, jack, jane;
>    iana:alternate <image.jpg>, <image.gif> .
> 
>  <image.jpg> awol:type "image/jpeg" .
>  <image.gif> awol:type "image/gif" .
> --------------------------------


FWIW, Callimachus allows DESCRIBE operations on resources, including images, that act like this.


> 
> But that still leaves the question what happens if one GETs <image.jpg> 
> without an image/* mime type. Does one get a redirect to the previous
> metadata file served as Turtle? Or does the server just return the image?


I hope the default behavior for non-LDPRs is to return their default Content-Type.


Regards,
Dave
--
http://about.me/david_wood


> 
> And if one deletes the collection, does <image.jpg> not also get deleted?
> 
> Henry
> 
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>