Re: [xri] URIMap element (was: XRD trusted discovery workflow)

My takeaway from the recent URIMap discussion is that there are two "levels" where we need URI mapping.

The first one is at the XRD level (the site-meta level). The use case here is, "I have URI X and I need to find the XRD for it." Finding that XRD can require requesting the site-meta file and then using it's URIMap to find the XRD (I understand site-meta may not be XML so it may not have a URIMap element, but it would be whatever the URI mapping equivalent is).

The second level is following a link from one XRD to a related resource. The use case here is, "I have the XRD for URI X and now I want the URI Z for the resource whose relation is Type Y". Computing URI Z from URI X can require a URIMap.

It seems that for the first level, the URIMap element should be in the /site-meta file (or the XRD that serves that role if we support that option).

I'm a bit confused about our scope here.

First, is a "URIMap" formally declared somewhere (perhaps as part of XRI already, or somewhere else?). The reason I ask is that it seems to be used as something with meaning outside of just being a URITemplate.

Using the "URIMap" in the way you describe it in your "level one" example assumes quite a bit about URI dereferencing -- namely that all URI's should be de-referenced (i.e., turned into a URL) via the process we outline in whatever becomes XDI.

Are we really trying to do that with XDI?

For the second level, the URIMap element should be a child of <Service> (or <Link> if we call it that).

Do I have this right?

=Drummond

From: sappenin@gmail.com [mailto:sappenin@gmail.com] On Behalf Of David Fuelling
Sent: Thursday, December 11, 2008 11:36 AM
To: Dirk Balfanz
Cc: Brian Eaton; xri@lists.oasis-open.org
Subject: Re: [xri] XRD trusted discovery workflow

On Thu, Dec 11, 2008 at 7:10 PM, Dirk Balfanz <balfanz@google.com> wrote:

I do think that something like

<Service>
<Type>uri-to-uri-map</Type>
<URIMap>...</URIMap>
</Service>

doesn't make much sense b/c both the <Type> element _and_ the <URIMap> element say that this is a URI map. We don't need to say it twice.

I disagree. The <Type> describes the service (It's a way to map URI's, e.g.). The URIMap is the way you go about mapping the URI.

If you omit the <Type>, then how does an XRD consumer know that the URIMap is supposed to be used to map URI's to URL, instead of doing something with some other Service-Type, like OpenID.

As an example, these two Services are very different, despite having the same URIMap.

<Service>
<Type>http://xrd.something/GenericURIMap</Type>
<URIMap>http://example.com?uri={uri}</URIMap>
</Service>

and

<Service>
<Type>http://specs.openid.net/auth/2.0</Type>
<URIMap>http://example.com?uri={uri}</URIMap>
</Service>

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