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RE: Role of intermediary

From: Paul Denning <pauld@mitre.org>
Date: Fri, 26 Jan 2001 11:35:11 -0500
Message-Id: <>
To: Steve Vinoski <vinoski@iona.com>, "Williams, Stuart" <skw@hplb.hpl.hp.com>
Cc: "'xml-dist-app@w3.org'" <xml-dist-app@w3.org>
At 10:56 AM 2001-01-26, Steve Vinoski wrote:

>I strongly agree with Stuart's direction here. Marc Shapiro wrote a 
>seminal paper regarding this "intermediary chaining" approach to 
>distributed computing a number of years ago. You can find it here: 
>One of the draft scenarios, DS6, talks specifically about encryption. Note 
>that in an intermediary chaining model, encryption is essentially just 
>another quality of service provided by the binding -- the chain of 
>intermediaries -- logically connecting the sender to the receiver. 
>Encryption, compression, transportation, marshaling, and even 
>receiver-side dispatching all act as intermediaries in the chain. This 
>model is extremely flexible and upgradable, and yet when implemented 
>correctly it works very efficiently in practice.

DS810 [1] is about QoS.

Maybe its a subtle distinction, but Steve mentions QoS "provided by the 
binding".  I envision an XP Module (above the XP core) also involved with 
QoS, which may influence the selection or behavior of bindings (below the 
XP core).

Also, I advocated separate DS's for with and without Intermediaries [2].  I 
was thinking here in terms of using the usage scenarios as test cases 
during development of an XP implementation.  I would not want to test 
without Intermediaries and try to claim it would also work with 
Intermediaries (without testing it).

[1] http://lists.w3.org/Archives/Public/xml-dist-app/2001Jan/0100.html
[2] http://lists.w3.org/Archives/Public/xml-dist-app/2000Dec/0235.html

Received on Friday, 26 January 2001 11:41:41 UTC

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