[OpenID] Summarizing my grouse with XRD

[John Kemp]

John Bradley wrote:
> It means that some protocol that is using XRD is defining the subject 
> via some external mechanism.

So the XRD spec. is a template spec. meant to be simply incorporated by 
reference into other specs. I guess?

> 
> In the HTTP protocol case there may be an implicit subject based on the 
> identifier that is being resolved.

As mentioned earlier, if the _subject_ of the XRD is identified 
(implicitly) by the same URI used to retrieve the XRD itself, then that 
seems rather circular.

> 
> All normal http caching would apply in the http: case.

Sure, I'm not quibbling with caching...

> 
> In the IMI/SAML case we have discussed pushing a XRD as a assertion/claim.
> 
> In that case the subject may be the same as the saml:NameID in the 
> containing saml:Assertion.
> 
> It could perhaps be argued that putting a xrd:Subject and signature 
> inside a signed saml:Asertion is un-neccicary.
> 
> Suffice to say it is up to the protocol using XRD to decide what to make 
> of a XRD without a xrd:Subject.

OK, I think I've understood ;)

Cheers,

- johnk

> 
> John B.
> 
> On 2009-10-21, at 3:09 PM, John Kemp wrote:
> 
>> John Bradley wrote:
>>> Yes a XRD can be used for identity.  In that case it should be a 
>>> signed XRD (with Subject)
>>> However a XRD can be used to describe any resource (URI).
>>
>> What does it mean then (in XRD terms) if an XRD doesn't identify the 
>> resource it describes (ie. it doesn't have a subject)?
>>
>> - johnk
>