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Subject: RE: [xdi] on global cross references and the link contract use case


I forgot, in the message below, to include the “note” I mentioned when I said, “See note below”.

 

The note was about the next message I’m about to send on the Use-Mention Distinction. See that email for more.

 

=Drummond

 


From: Drummond Reed [mailto:drummond.reed@cordance.net]
Sent: Wednesday, November 26, 2008 4:11 PM
To: 'Chasen, Les'; jbradley@mac.com
Cc: giovanni.bartolomeo@uniroma2.it; xdi@lists.oasis-open.org
Subject: RE: [xdi] on global cross references and the link contract use case

 

What the @cordance authority service does when given the subsegments…

 

            =drummond

            *(=drummond)

 

…is up to the @cordance authority server. I agree that @cordance authority server could decide to consult another authority server in its response, but it still controls the response it its own context no matter where it gets the XRD or what it puts in it. For example, it could:

 

1) Have a policy that both of the subsegments above are synonyms in its context and that they return the same XRD.

2) Have a policy, as Les suggests, that *(=drummond) will return the XRD (or selected SEPs from XRD) from the = registry. (See note below.)

3) Have any other policy that applies to global subsegments and/or local cross-references.

 

IMHO the authority of an authority server is sacrosant. It can apply any policy it wants to produce the next XRD. What matters is that:

 

A) Parsing of the next subsegment to be resolved is always 100% unambiguous for a resolver.

B) The resolver always hands the authority server EXACTLY the next subsegment to be resolved (or all remaining subsegments to be resolved in lookahead resolution).

C) The authority server return a valid XRD (or an XRDS in the case of lookahead resolution).

 

=Drummond

 


From: Chasen, Les [mailto:les.chasen@neustar.biz]
Sent: Wednesday, November 26, 2008 10:03 AM
To: jbradley@mac.com
Cc: giovanni.bartolomeo@uniroma2.it; xdi@lists.oasis-open.org
Subject: Re: [xdi] on global cross references and the link contract use case

 

I need to stick with simple examples and in this case there is only one authority, @cordance, in question. under the current proposal @cordance is asked for both =drummond and *(=drummond) and it returns its own xrd if one exists within @cordance. We have never discussed whether @cordance may go to the = authorty server for drummond when it is contained within *(=drummond). I think that maybe interesting behavior.

--------------------------
http://xri.net/=les.chasen


From: John Bradley
To: Chasen, Les
Cc: giovanni.bartolomeo@uniroma2.it ; xdi@lists.oasis-open.org
<xdi@lists.oasis-open.org>Sent: Wed Nov 26 12:44:00 2008
Subject: Re: [xdi] on global cross references and the link contract use case

Les,

 

I started off with that position.   I now think they are separate queries to the next authority server.

 

I think that the parenthesized statement may contain multiple subsegments is the important thing.  

Once we have a way to encapsulate multiple subsegments to be handed to an authority server it is hard to stop someone from only putting in a single subsegment. in the cross ref.

 

I think the simple principle is that things in parenthesis are opaque to the resolver and handed to the next authority server and things not in parenthesis are resolved left to right one subsegment at a time.

 

I also don't think that in ether case @cordance is being asked anything about the global =drummond if one exists.

 

In the first case the authority server for @cordance is being asked for a XRD for the subsegment =drummond the = is treated as part of the subsegment itself

In the second  case the authority server for @cordance is being asked for a XRD for the subsegment  *(=drummond) 

 

I think the latter could be taken that the authority server may look someplace else to get the XRD for the cross reference.

I think in the former case =drummond is a subsegment in its authority server.

 

The question is if it is just a regular subsegment is using = as a separator going to confuse people.

 

=drummond is just a regular subsegment with some inference by Cordance that its =drummond has something to do with the global =drummond though XRI makes no such claim other things using XRI like XDI may.

 

 

John B.

 

 

On 26-Nov-08, at 9:23 AM, Chasen, Les wrote:

 

Let's not complicate this with +phone. My question is does @cordance return a different xrd for =drummond and *(=drummond)? This proposal says yes. I disagree with this behavior. I think @cordance is being asked for its representation of =drummond in both cases.


--------------------------
http://xri.net/=les.chasen

 


From: John Bradley
To: Chasen, Les
Cc: giovanni.bartolomeo@uniroma2.it <giovanni.bartolomeo@uniroma2.it>; xdi@lists.oasis-open.org
<xdi@lists.oasis-open.org>Sent: Wed Nov 26 12:11:59 2008
Subject: Re: [xdi] on global cross references and the link contract use case

 

From a XRI resolution perspective I see a difference in what @cordance's authority server is asked for.

 

@cordance=drummond                                  , @cordance is asked for the XRD for =drummond

@cordance=drummond+phone           , @cordance is asked for the XRD for =drummond , @cordance=drummond is asked for the XRD for +phone

@cordance*(=drummond)                  , @cordance is asked for the XRD for *(=drummond)

@cordance*(=drummond+phone)      , @cordance is asked for the XRD for *(=drummond+phone)

 

Parenthesis in the first segment tell the resolver to treat the contents as an opaque string and pass it to the next authority server.

 

The resolver Parenthesis in the path are not significant to the resolver they would be matched during service selection as they are now.

 

One thing we did start talking about at the F2F is what the syntax to indicate special processing on a cross reference.

 

An example:

 

Is $XRD a node that has as its authority service one that performs XRD resolution on the next subsegment.

 

So is a $ word in XRI resolution a node that points to a specialized authority service?

 

Certainly a resolver has the option of shortcutting resolution through querying the $XRD authority server if it understands the $XRD word.

 

Under Drummond's proposal we do have to have a theory about what + and $ in the first subsegment resolve to.

 

John B.

 

 

On 26-Nov-08, at 6:51 AM, Chasen, Les wrote:

 

Hi Giovanni -

A cross reference is putting the thing cross referenced inside the context of the xri that contained the cross reference. Terminology in this proposal has been changing but the thing that hasn't is that in both cases the outer authority is returning its xrd for the reference. That is, in the example below, cordance is returning its xrd for =drummond.

@cordance=drummond
@cordance*(=drummond)

So we only support the 'inside' (or better stated container) concept. Now it may be interesting to consider a resolution process which rather than asking @cordance for =drummond we ask = for drummond. Today that does not exist.

Have a happy thanksgiving.

Thanks

Les

--------------------------
http://xri.net/=les.chasen

 


From: Giovanni Bartolomeo
To: Chasen, Les
Cc: XDI
Sent: Wed Nov 26 09:35:43 2008
Subject: RE: [xdi] on global cross references and the link contract use case

 

Hello Les,

First, thank you for having read the contribution! Unfortunately I'm probably not the best person which can answer your question, as I'm not an expert of XRI2.0. I limited to develop my contribution in the scope of the current proposal ( http://wiki.oasis-open.org/xri/XriThree/GcsDelimiter), which, I personally support for one specific reason: http://lists.oasis-open.org/archives/xri/200811/msg00043.html.

I think Drummond's reply http://lists.oasis-open.org/archives/xdi/200811/msg00031.html is a good technical explanation of this, expecially the last statement: in an ordered set, you are not referencing across contexts. The context is the ordered set itself. For example, in $sig$d, the context for $d is $sig. Which I understand as follow: put an object inside a context is not exactly the same as referencing it from that context).

The core of this issue - that's my guess and not a technical explanation -  is probably that XRI2.0 did not consider the need to "put an instance of an object inside a context", but just to "cross reference" it. That is instead a fundamental capability for XDI (and for any human or machine understandable language).

I'll be happy to answer any further questions you might have on the contents of the contribution itself.

Kind Regards,
Giovanni

At 13.36 25/11/2008, Chasen, Les wrote:

Hi Giovanni.  I had a chance to read this.  While I like what you guys
are doing with link contracts I fail to understand why all of these
examples do not work with XRI 2.0 style cross references. 

> -----Original Message-----
> From: Giovanni Bartolomeo [ mailto:giovanni.bartolomeo@uniroma2.it]
> Sent: Wednesday, November 19, 2008 12:02 PM
> To: XDI
> Subject: [xdi] on global cross references and the link contract use
> case
>
> Hello,
>
> some weeks ago I mentioned that I was playing a bit with the
> semantics of link contracts. Better to say, with the global cross
> references applied to the link contract use case. After the issue of
> XDI RDF model v.11, I put my thoughts in a document which you can find
> below.
> Maybe just semantic nuances, but your comments will be welcome.
>
> Thanks,
> Giovanni

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