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Re: Abstract Model contribution for Intermediairies (repost)

From: Yuhichi Nakamura <NAKAMURY@jp.ibm.com>
Date: Wed, 14 Mar 2001 15:48:44 +0900
To: "Jean-Jacques Moreau" <moreau@crf.canon.fr>
Cc: "'xml-dist-app@w3.org'" <xml-dist-app@w3.org>
Message-ID: <OF23390D68.C8FDCD7B-ON49256A0F.0024A4B7@LocalDomain>

Hello Jean-Jacques,
Good job!  I have some questions.
For 5, assume that a sender sends a request via gateway.  Others should
know the gateway address, but do not have to know the
address of the sender application.  Even in that case, the sender address
MUST be recorded in the path record?
For 6, this is very good restriction from implementation point of view.
However, a response is replied directly from an ultimate
receiver to the initial sender, according to "XML Abstract Processing
Model" document.  Any idea?
Is there consensus how to address intermediaries (and handlers in the
abstract model document)?
Best regards,

Yuhichi Nakamura
IBM Research, Tokyo Research Laboratory
Tel: +81-46-215-4668
FAX: +81-46-273-7428

From: "Jean-Jacques Moreau" <moreau@crf.canon.fr>@w3.org on 2001/03/14

Please respond to "Jean-Jacques Moreau" <moreau@crf.canon.fr>

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      Ibbotson/UK/IBM@IBMGB, "Krishna Sankar (E-mail)" <ksankar@cisco.com>,
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Subject:  Abstract Model contribution for Intermediairies (repost)


Following Mark Jones' example, and building on the Intermediaries
discussion, Mark Nottingham's paper, and your own text, I would like
to offer the following text as a starting point for a section on
Intermediaries in the Abstract Model.

Feedback is welcomed.


PS. I have tried to keep the model simple, so my apologies in advance
if you do not recognize your favorite feature.

                    Abstract Models for Intermediaries

             Jean-Jacques Moreau, Canon Research Centre France

          W3C XML Protocol Working Group, Abstract Model subgroup

An Abstract Model for Intermediaries


   An XML Protocol message may be delivered through zero or more
   The XML Protocol message specifies a set of intermediaries to visit, and
   the order in which they will be visited. The list of intermediaries, as
   specified by the sender, is called the initial path.
   An XML Protocol intermediary may modify the path before forwarding the
   message to the next intermediary in the chain, and hence possibly change
   this next intermediary. This permits to cater for cases where the full
   path is not known in advance, for example where there exists a proxy or
   caching server along the way.
   An intermediary may only add to the path. More precisely, it may only
   add one or more nodes to visit before the original next hop.
   An intermediary must record its identity/address within the message,
   before forwarding it to the next intermediary in the path. This permits
   to record the actual route followed by the message.
   An XML Protocol response follows the same path as the corresponding
   request, but in reverse order.
   The recorded route is used to compute the reverse path.
   When a fault occurs at an intermediary, further message forwarding is
   cancelled, and the fault is delivered as a response through the reverse
Received on Wednesday, 14 March 2001 01:49:20 UTC

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