Re: [xri] Re: questions about LRDD / OpenID

[Will Norris <will@willnorris.com>]

hmm, looks like I was a bit off with my answers... sorry about that.


On Mar 23, 2009, at 11:09 AM, Eran Hammer-Lahav wrote:
>
> On 3/23/09 8:44 AM, "Markus Sabadello" <markus.sabadello@xdi.org>  
> wrote:
>
>> 1. When performing LRDD on Joe's OpenID http://example.com/joe, you  
>> say that
>> in step 3 the relying party gets the /host-meta file and looks for  
>> the
>> "Link-Pattern" entry. My question is, shouldn't it also look for a  
>> "Link"
>> entry?
>
> Not when performing LRDD. The /host-meta Link record is currently  
> specified
> to apply to all resources under the same authority (wording I plan to
> change), but such records are not used in LRDD. The short answer is  
> that
> there are many other methods we could have included but decided to  
> limit the
> list to three specific methods.
>
> The long answer is how that it creates a complicated flow where it  
> is now
> clear which records to use.
>
> OpenID may choose to use /host-meta Link for performing a site-wide
> discovery that is not for a specific URI. But that is not part of  
> LRDD.

Given than several large providers are doing OP-driven identifier  
selection (Yahoo and Google immediately come to mind), are you  
expecting that this will be a likely possibility?


>> 3. It seems that XRD is now very similar to the various Link  
>> mechanisms. My
>> question is, in your OpenID example, could the same goals be  
>> achieved without
>> using XRD at all? E.g. when performing LRDD on Joe's OpenID
>> http://example.com/joe, instead of discovering an XRD via  
>> describedby links,
>> couldn't you also directly discover the OpenID provider:
>
> While they are semantically identical, an application using XRD over  
> LRDD
> will only look for application records in the XRD and not in other  
> links.
> This is mostly for interoperability which is the main reason for all  
> this
> work.
>
> Think about it this way, the same way LRDD is making some restrictive
> choices about which links to use, applications using XRD are  
> applying the
> same pattern by limiting where their application-specific meta is  
> located.

This assumes the application is using XRD+LRDD exclusively.  OpenID is  
already using its own fall-back mechanism today in additional to Yadis/ 
XRDS, in the form of the <link> HTML elements.  I understand it will  
be up to the OpenID community to define how any new discovery spec  
works, but what are you expecting?  Do you foresee them keeping the  
<link> HTML elements?  If so, isn't it likely that we could expect to  
see use of the Link HTTP header as well?

-will