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Re: Role of intermediary

From: marwan sabbouh <ms@mitre.org>
Date: Thu, 25 Jan 2001 10:55:21 -0500
Message-ID: <3A704C69.EE3C03D@mitre.org>
To: "Williams, Stuart" <skw@hplb.hpl.hp.com>
CC: "'Lerner, Michah, ALSVC'" <michah@att.com>, "'xml-dist-app@w3.org'" <xml-dist-app@w3.org>
Hi Stuart;

I see where you are heading with this.  Am I correct to say that you
view  the intermediary as the processing element that apply some sort of
transformation to that incoming message?  Does the requirement
specification  support this notion?  Please don't get me wrong, I am not
advocating one way or another.  I'm just trying to get the definition
down.

Marwan

"Williams, Stuart" wrote:
> 
> Hi Marwan,
> 
> There is some discussion of whether the header/body distinction is really
> useful [1]. In the context of what I think Michah was raising, I'm not sure
> that the distinction is really useful either.
> 
> You can thing of a chain of processing elements strung out between sender
> and reciever. This chain is segemented into short chunks by the partitioning
> of these elements amongs sender, intermediaties and receiver. Together you
> can think of this chain performing some transformation a message passing
> down the chain. Steering through the chain might be dynamic, it might be
> prescribed in some way by the sender, it might not be the same between
> successive messages sent between the same sender/receiver pair... we have
> settled none of these questions (that I am aware of).
> 
> I think the issue that Michah was drawing our attention to was the
> relationship between the order of elements in the whole chain and the
> transformation applied between sender and receiver. We could reorder
> intermediaries and move segements of the chain around and/or we could alter
> the order of module processing within a single intermediary.
> 
> It would be nice for the transformation to be completely independent of
> order modules are processed in. Everything (at least end-to-end) would be
> nicely orthogonal... it's not clear to me that its possible to do in
> general.
> 
> There is also the question of the partial transformations seen at each
> intermediary... indeed at each processing element in the chain. These
> partial transformations (from receiver to current point in the chain) will
> in general depend on processing order.
> 
> Stuart.
> [1] Thread beginning at:
> http://lists.w3.org/Archives/Public/xml-dist-app/2001Jan/0110.html
> 
> > -----Original Message-----
> > From: marwan sabbouh [mailto:ms@mitre.org]
> > Sent: 25 January 2001 13:57
> > To: Williams, Stuart
> > Cc: 'Lerner, Michah, ALSVC'; 'xml-dist-app@w3.org'
> > Subject: Re: Role of intermediary
> >
> >
> > Michah
> > "In that regard I would expect it to try to take a position
> > with repect
> > to the semantic properties of chains of
> >             intermediaries, where there are questions about
> > whether the
> > relative positioning of XP blocks in messages and the order that
> > messages
> >             (and blocks) are processed at intemediaries semantically
> > significant or not to the overall operation performed by the
> > chain (and
> > to
> >             the partial view of the operation seen by the
> > intermediaries
> > the message passes through)"
> >
> >
> > My understanding is that Intermediaries only process headers
> > and not the
> > body of an XP message.  Right?  Is that what you meant by :
> > "...and the
> > order that messages (and blocks) are processed at intemediaries
> > semantically significant..."?
> >
Received on Thursday, 25 January 2001 10:37:32 GMT

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