[OpenID] Comment on new Draft host-meta
Santosh Rajan
santrajan at gmail.com
Sun Oct 25 04:20:09 UTC 2009
Hey Peter,
Nice to see you back :-)
I can understand your point. I don't have a problem with host-meta having a
"Scope". My problem is that it can't replace the Subject.
I am convinced that any spec that allows an XRD without a Subject, has a
hole in it, big enough to sail an aircraft carrier through.
The reason why the host-meta does not have a Subject, is not so much because
conceptually it does not have one. On the other hand it is because no one
has come up with an agreeable Subject for everyone. The best one I have seen
so far is
<Subject>dns:example.com</Subject>
I don't see a problem in adding the above Subject to the host-meta XRD. Now
if you "really" need a <Scope> over and above the <Subject>, I am Ok with
that. Even though I believe a judicious use of a Subject and Aliases will
obviate the need for a Scope.
On Sun, Oct 25, 2009 at 8:58 AM, Peter Williams <home_pw at msn.com> wrote:
>
> Santosh:
>
> Take the first example:-
>
> <?xml version='1.0' encoding='UTF-8'?>
> <XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'
> xmlns:host-meta='http://host-meta.net/ns/1.0'>
>
> <host-meta:Scope scheme='http' authority='example.com' />
> <host-meta:Scope scheme='http' authority='www.example.com' />
>
> <Link>
> <Title xml:lang='en-us'>Site License Policy</Title>
> <Rel>license</Rel>
> <URI>http://example.com/license</URI>
> </Link>
> <Link>
> <Title xml:lang='en-us'>Resource Descriptor</Title>
> <Rel>describedby</Rel>
> <URITemplate>http://meta.example.com?uri={uri}</URITemplate>
> </Link>
> </XRD>
>
>
> If I use my old-for-new interpretation (which uses what I mostly understood
> from the XRI model in its era):-
>
> This XRD has no XRD.subject. This means there is no named
> XRI-style-authority bound to this XRD. Ok. So its an anonymous
> XRI-style-authority. (No big deal in graph theory, where anonymous nodes
> abound.)
>
> But, rather than be bound to any named XRI-style-authority, the XRD does
> have scope - declared using some IETF-defined XRD extension vocabulary for
> scope rules. In my mental model, the scope is a simple identifier class
> pattern - that defines a set of XRI-style-authorities to which this XRD is
> bound. (In graph theory an inverse functional relation for names bound to
> this XRI-style-authority. No big deal.)
>
> >From what I know of the old XRI algebra (and its polyarchical basis),
> several named XRI-style-authorites could always share an actual XRD. So, I
> dont find the notion of scope being used to bind several
> XRI-style-authority
> to 1 XRD particularly strange. Its an applciation of the the whole synonym
> thing - that made XRI so interesting to start with. (again, none of this is
> particular weird in graph theory, where any node can have n self-referring
> arcs with unique names)
>
> So, the XRD attaches to all XRI-style-authorities (x elementOf X) where any
> name/identifer x meets the scope pattern (of which there are 2). The
> identifier form of x is an http URIs (see scope rules), which (as usual)
> have a scheme and URI-authority component (circa 1994). (Nothing hard here,
> but a bit of algebra gives us a formal variable to now play with in other
> formulae.)
>
> in the XRD (now implicitely late-bound to probably multuple
> XRI-style-authorities meeting the scope patterns) there are two SEPs
> (sorry,
> I MUST learn to say "links").
>
> One link has a static URI locating copyright metadata, as declared in its
> relationship field. I can GUESS that host-meta extension defines some
> semantics that declare that the linked metadata (an XRD document, I assume)
> applies to any and all XRI-style-authorities x...matching the scope
> patterns. (Its a guess, but seems reasonable. if its right, that was not
> hard: here is the copyright file that is incorporatde by reference into any
> resource whose uri=x, where x satisfied the scope rules)
>
> Another SEP/link has a URI template. It seems to say: given the uri x
> identifying any 1 of the XRI-style-authority matching the scope patterns,
> additional metadata about that uri x can be found by querying
> http://meta.example.com?uri=x. (Now that all Peter's guess, but none of it
> seems hard or unreasonable. This is the same model as Henry gave about foaf
> metadata describing the URL at which the foaf document bearing the metadata
> can be retrieved.)
>
> Now, I have to say that I found the writing in the internet-draft bizarre,
> unapproachable, aloof and overly pseudo-intellectualized.
>
> The example however speaks for itself and (formal writing issues aside)
> seems obvious and useful.
>
> Now IGNORE my interpretative basis (as its all wrong, apparently).
> Strangely, though, it makes perfect sense - which is far more than RFC's
> written introduction did.
>
>
>
> Santosh Rajan wrote:
> >
> > Quoting from
> >
> > http://www.ietf.org/id/draft-hammer-hostmeta-01.txt
> >
> > "host-meta document SHOULD NOT include the 'Subject' or 'Alias' XRD
> > elements since these elements require a valid URI to identify the
> > resource being described, which is not available for the host-meta
> > scope."
> >
> >
> > Yet you have taken the very same URI's, that should have been in the
> > Subject
> > and Alias fields to begin with, split them into scheme and authority,
> > stuck
> > them into a new "Scope" element and embelished it with a new namespace to
> > give it more legitimacy. Logically i dont see any difference from using
> > the
> > Subject and Alias.
> >
> >
> > "not available for the host-meta scope" is very different from "not
> > available for the host-meta". You cannot justify ignoring the Subject of
> > the
> > XRD, based on its "Scope". The Subject of an XRD is about the XRD itself
> > and
> > not its scope.
> >
> >
> > The host-meta is not some "Thing" that resides in somebody's backyard, so
> > that it cannot have a URI to identify it. As for differentiating the
> > host-meta from the actual URL resource, haven't we already done it with
> > the
> > ".well-known" path? There is no valid justification to ignore the Subject
> > here.
> >
> >
> > As for your use of "authority", i see a couple of problems using it.
> > 1) "authority" has a "userinfo" part that will break your usage of it in
> > this context.
> > 2) URN's do not have a authority part. scheme="acct",
> > authority="yahoo.com"
> > is meaning less.
> >
> > --
> > http://hi.im/santosh
> >
> > _______________________________________________
> > general mailing list
> > general at lists.openid.net
> > http://lists.openid.net/mailman/listinfo/openid-general
> >
> >
> > -----
> >
> > Santosh Rajan
> > http://santrajan.blogspot.com
> >
>
> --
> View this message in context:
> http://www.nabble.com/Comment-on-new-Draft-host-meta-tp26036844p26045022.html
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>
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--
http://hi.im/santosh
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