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Re: Re: Intermediary Discussion

From: Marwan Sabbouh <ms@mitre.org>
Date: Wed, 7 Feb 2001 09:30:29 -0500
Message-ID: <00e101c09112$85397cf0$533e5381@mitre990iru6mg>
To: "Martin Gudgin" <marting@develop.com>, "XML Protocol Comments" <xml-dist-app@w3.org>
> 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.

The answer for this one should be no. In my mind, any request can traverse a
different set of intermediaries than the response.

in [1], I tried to present a summary of Soap's notion of intermediary.

[1]-http://lists.w3.org/Archives/Member/w3c-xml-protocol-wg/2001Feb/0004.htm
l



Message-ID: <00cb01c08c59$6f397b70$533e5381@mitre990iru6mg>
From: "Marwan Sabbouh" <ms@mitre.org>
To: "Martin Gudgin" <marting@develop.com>, "XML Protocol WG"
<w3c-xml-protocol-wg@w3.org>
Date: Thu, 1 Feb 2001 09:15:30 -0500
Subject: Re: Intermediary Discussion

Martin

Thanks for sending out the e-mail. Although, we may not need to define (1)
and (2), we could still learn from them as they make good examples of
intermediaries. the definition we have in the glossary is vague at best and
needs to be changed.



Some questions I have on intermediaries are:

how do we distinguish between an intermediary and an ultimate destination?

InSOAP the target URI for the ultimate destination is pushed down to the
protocol binding. (See issue RPC 1 of XP mappings to soap). Whereas the
target URI for an intermediary is specified in the envelope header.

Does an intermediary access the body of XP message?

In soap, the body element is intended for the final destination. Whereas
intermediaries act on the header element.



Finally, would it be useful for an intermediary to insert a header that
could be intended for the sender o of the message, as opposed to the
recipient of the message or the next hop?





----- Original Message -----
From: "Martin Gudgin" <marting@develop.com>
To: "XML Protocol Comments" <xml-dist-app@w3.org>
Sent: Tuesday, February 06, 2001 5:16 PM
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 09:19:31 GMT

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