Re: [xri] Backtracking

["Chasen, Les" <les.chasen@neustar.biz>]

Title: Re: [xri] Backtracking

I am not sure when this change came about.  REFs should only be followed in the search of a service whether at the xrd level or service level.

Drummond, in one of you last emails you indicate that a ref and a redirect at the xrd level have the same behavior in that it is followed without inspection of the local SEPs.  This is fine for redirect but not ref.  Ref should only be followed if the service being sought is not found.

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


----- Original Message -----
From: John Bradley <jbradley@mac.com>
To: OASIS XRI TC <xri@lists.oasis-open.org>
Cc: Kermit Snelson <ksnelson@subjectivity.com>; Tan, William
Sent: Thu Oct 25 20:38:42 2007
Subject: [xri] Backtracking

Reading the spec 11.5 and looking at the flowcharts we now have 
backtracking for refs at the XRD level.

For these XRD level refs we iterate through refs and redirects in 
priority order.

My question is what causes backtracking.  As we have not moved to SEP 
selection at his point, is success just returning the XRD?

I see and completely agree on backtracking if the XRD is not returned.

However the spec now indicates that we move to SEP selection once the 
XRD is returned and if the SEP is not found we backtrack to the next 
ref in authority  resolution.

Before we added refs to SEPs this perhaps made more sense.

I prefer the notion of doing this with SEP refs:

1. authority resolution and finding the XRD,
2. Service Selection,
3. Iterating through authority resolution and SEP selection for each 
ref in priority order.

If we backtrack from SEP selection into authority resolution I think 
it increases implementation complexity.

So we can leave the current behavior and backtrack if no SEP is 
found,  or change it to only backtrack if no XRD is found.

I am happy with the backtracking on the SEP refs I think that makes 
sense.

I will contribute a clarification for 11.5 depending on what behavior 
people want.

I particularly would like Kermit and Wil's opinions.

I can live with it ether way as long as its unambiguous.