[OpenID] host-meta and "acct:"

[Will Norris]

So we have two competing ideas about what it means for an XRD to not  
identify the resource it is about.  James suggests that it is whatever  
resource points to the XRD and claims that the XRD is its descriptor.

James.H.Manger at team.telstra.com> wrote:

> <XRD xmlns=…><Link><Rel>author</Rel><URI>http:// 
> jim.footyfanatics.fans/#me
> </URI></Link></XRD>
>
> There is no <Subject> element. This is metadata for any resource  
> that says
> this is its metadata, ie any resource with a “describedby” link  
> pointing
> here. There is no URI for that collections of resources that could  
> be put in
> <Subject>.


Alternately, Santosh suggests that it is the XRD resource itself.

On Nov 5, 2009, at 7:43 AM, Santosh Rajan wrote:

> All the three XRD's you mentioned are also "Resources", and they  
> also have
> <Subjects> that happen to be the very URI's that you use to address  
> them.
> eg,
> <Subject>http://mywebsite/jim.footy.xrd</Subject>


The correct answer is that the subject is undefined.  So both of the  
above answers are wrong, but they both COULD be right.  There are only  
two defined ways today for an XRD to identify the resource(s) it is  
describing.  Those are the <Subject> element defined in the XRD spec,  
and whatever element Host Meta ends up defining.  Aside from those  
two, nothing more has been defined.  There is no implicit subject  
according to the XRD spec.

If an application or protocol wants to define some other mechanism to  
identify the resource an XRD is about in the absence of a <Subject>  
element, they are free to do so.  In fact, they are encouraged to so.   
We left it undefined intentionally because there is no one right  
answer... it depends on your application, your security and trust  
requirements, and any number of other factors.

-will