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RE: Re: Intermediary Discussion

From: Williams, Stuart <skw@hplb.hpl.hp.com>
Date: Wed, 7 Feb 2001 17:42:18 -0000
Message-ID: <5E13A1874524D411A876006008CD059F1921C1@0-mail-1.hpl.hp.com>
To: "'Martin Gudgin'" <marting@develop.com>
Cc: XML Protocol Comments <xml-dist-app@w3.org>
Hi Martin,

Looks like we're getting there. I do have a minor glitch which is the use of
the terms "XP Sender" and "XP Receiver" in the definition. We have a bunch
of terms that need to be 'cast' together. I've been having problems with
some of the glossary terms in trying to use them consistently within the
abstract model, in particular what is implied by fig 4 in the requiremenst
document and the narrative text definitions for the terms: "XP Sender", "XP
Receiver" and "XP Processor" (see [6]).

Basically, I like the flavor of where this is getting, and from a loose
terminology point-of-view, but I am concerned that we have a bunch of
related terms where tweaks in definition might have knock on effects.

Regards

Stuart

[6] http://lists.w3.org/Archives/Public/xml-dist-app/2001Feb/0004.html


> -----Original Message-----
> From: Martin Gudgin [mailto:marting@develop.com]
> Sent: 06 February 2001 22:17
> To: XML Protocol Comments
> Subject: INT: Re: Intermediary Discussion
> 
> 
> OK, there has been *some* discussion of this topic [1-2]. The 
> Abstract Model
> Group have also been thinking about intermediaries[4-5]. Mark 
> Nottingham has
> posted a document discussing intermediaries[3].
> 
> After reading these posts I think we are still some way from 
> consensus on
> *exactly* what an XP intermediary is but we do seem to have 
> broad agreement
> that;
> 
> 1.    XP Intermediaries sit between the sender of a request 
> and the ultimate
> recipient of that request.
> 
> 2.    XP Intermediaries perform some processing of the 
> request message.
> 
> 3.    Exactly what processing occurs at an intermediary is defined by
> extension blocks.
> 
> 4.    There needs to be a way of addressing intermediaries 
> from within an XP
> message.
> 
> 5.    There may be multiple intermediaries between the sender and the
> receiver.
> 
> 
> Open questions/issues...
> 
> Do XP Intermediaries also sit between the sender of the 
> response and the
> ultimate receiver of that response? And hence also process 
> the response
> message assuming one exists.
> 
> If the answer to the above question is 'Yes' is the set of 
> intermediaries
> the same for both the request and response message?
> 
> If a given intermediary is the 'target' for more than one 
> extension block in
> an XP message does a processing order need to be defined and 
> is so how do we
> define it?
> 
> In terms of addressing intermediaries it's my feeling that we need to
> address ( ahem ) the following cases;
> 
>       a) absolute addressing ( must go to machine A )
>       b) by group ( must go to one of machine X, Y or Z )
>       c) by class ( must go to a machine running Windinux )
> 
> 
> So, coming to the purpose of this discussion which was to 
> provide a new
> definition for XP intermediary here are few possibilities;
> 
> 1.    Taken from Hugo's mail ( thanks Hugo! )
> 
>   An XML Protocol intermediary is an application which processes a
>   defined set of blocks in an XML Protocol message along an XML
>   Protocol message path. It acts both as an XML Protocol receiver and
>   an XML Protocol sender in order to forward the XML Protocol message
>   towards the ultimate XML Protocol destination.
> 
> 2.    Slight amendment to the above to add notion of addressability
> 
>   An XML Protocol intermediary is an application, addressable from
>   within an XML Protocol message, which processes a defined set of
>   blocks in an XML Protocol message along an XML Protocol 
> message path.
>   It acts both as an XML Protocol receiver and an XML Protocol sender
>   in order to forward the XML Protocol message towards the ultimate
>   XML Protocol destination.
> 
> 
> 3.   Slight amendent to 3 to make the possibility of multiple 
> intermediaries
> more explicit
> 
>   An XML Protocol intermediary is an application, addressable from
>   within an XML Protocol message, which processes a defined set of
>   blocks in an XML Protocol message along an XML Protocol 
> message path.
>   It acts both as an XML Protocol receiver and an XML Protocol sender
>   in order to forward the XML Protocol message to the next recipient
>   in the message path which may be another XML Protocol intermediary
>   or the ultimate XML Protocol destination.
> 
> 
> Thoughts, comments, flames etc. all welcome...
> 
> Gudge
> 
> [1] http://lists.w3.org/Archives/Public/xml-dist-app/2001Feb/0006.html
> [2] http://lists.w3.org/Archives/Public/xml-dist-app/2001Feb/0011.html
> [3] http://lists.w3.org/Archives/Public/xml-dist-app/2001Feb/0026.html
> [4] http://lists.w3.org/Archives/Public/xml-dist-app/2001Feb/0021.html
> [5] http://lists.w3.org/Archives/Public/xml-dist-app/2001Feb/0023.html
> 
> 
> 
Received on Wednesday, 7 February 2001 12:42:33 GMT

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