Re: Proposal to register rel="about"

[Antone Roundy <electriceel@xxxxxxxxx>]

Erling Wegger Linde wrote:
> If you could use <link rel="about" href="htmlrepresentationofissue">
> together with for instance <content type="application/rdf+xml">RDF
> represenation here..</content>

I think that's what link/@rel="alternative" is for.

>>>>> The Atom use cases we refer to use Entries as containers to provide
>>>>> "metadata" about some web resource other than the Entry itself. For
>>>>> example,
>>>>> the GData Entry 
<http://gdata.youtube.com/feeds/api/videos/S_bcAOlK0io >
...
>>>> My impression upon looking at the entry is that you could do this 
instead
>>>> (and add an atom:summary element with textual content):
>>>>
>>>> <content src="http://www.youtube.com/watch?v=S_bcAOlK0io"; />
...
>> What if you use Atom entries as wrappers for other resources?
>> It seems to me that that's exactly what <content src="..." /> is for.
>
> No, I don't agree. What if you haven't got a proper "wrapper resource"
> to refer to, how could you use <content src=".."> then? You couldn't
> do that without creating a new resource right? And what if for
> instance you want to let a client understand that the <summary>
> element of an Atom entry is actually metadata about another resource?

Once again, I think this is exactly what <content src="..." /> is for. 
For an Atom entry to have its own content that ISN'T simply an 
alternative representation of an external resource, and have 
entry/summary be a summary of anything other than entry/content is a 
corruption of Atom.

I'm not sure what you mean by "wrapper resource" -- if you have an 
external resource which is what the entry metadata is about, then that 
external resource is the "content" of the entry.  If the entry contains 
additional content commenting on the external resource, then the entry's 
metadata should be about that additional content (and in THAT case, 
rel="about" might be an appropriate way to link to the external 
resource, but the entry metadata is still about the entry content).

If the external resource is the content of the entry and you point to it 
with content/@src, then the summary is metadata about the external 
resource -- atom:summary is a summary of atom:content, whether the 
content is included inline or not.

>> Allowing a link/@rel value to alter the
>> meaning of core Atom elements would be dangerous, because 
implementations
>> that don't understand the new @rel value (which they're not required 
to do,
>> and we rejected the idea of creating any sort of "mustUnderstand" 
mechanism)
>> would misinterpret the core Atom elements.
>
> Well, I can see your point. But from working with Semantic Web
> technology together with AtomPub I think that adding a
> link@rel="about" to the Atom format could make Atom(Pub) a bigger
> player in the Semantic Web (which I hope is the future).

I understand your point, but I think doing it the way you're wanting to 
would require redefining Atom in a way that's not backwards compatible 
with the existing RFC.

> I'm not sure if this would be such a dangerous addon to Atom as you
> indicate. I can't see why most clients can't keep on doing business as
> usual.

It goes back to this:

> We understand that an RFC that specifies the proposed rel="about"
> relationship would have to express which child elements of atom:entry
> pertain to the resource described by the Entry, and which to the Entry
> itself, whenever a rel="about" is present in an Entry.
...
> (a) /entry/id, /entry/published, /entry/updated, /entry/rights,
> /entry/link@rel="self", /entry/link@rel="license" pertain to the Entry
> (b) all other child elements of /entry that are in the Atom namespace
> pertain to the resource that is the target of the "about" relationship.

Existing implementations expect entry/author, entry/category, 
entry/content, entry/contributor, entry/link (whatever the @rel value 
is), entry/source, entry/summary, and entry/title to be metadata about 
the entry. If the existence of rel="about" changes the interpretation of 
these elements, implementations that aren't aware of rel="about" won't 
interpret them as the publisher intended.

Antone