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Re: [cuss] "isdn-uui" versus "isdn-network"

"Vijay K. Gurbani" <vkg@bell-labs.com> Thu, 21 November 2013 17:25 UTC

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Date: Thu, 21 Nov 2013 11:25:24 -0600
From: "Vijay K. Gurbani" <vkg@bell-labs.com>
Organization: Bell Laboratories, Alcatel-Lucent
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To: Andrew Allen <aallen@blackberry.com>, "bruno.chatras@orange.com" <bruno.chatras@orange.com>, "cuss@ietf.org" <cuss@ietf.org>
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Subject: Re: [cuss] "isdn-uui" versus "isdn-network"
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[As individual, of course.]

On 11/21/2013 09:31 AM, Andrew Allen wrote:
>
> I have some sympathy for Bruno's position. He is merely asking to
> align with the principle of "Be strict in what you send, but generous
> in what you receive".

I must say that I disagree.  I suspect that Postel's Law was not
designed to allow multiple tokens to represent the same semantic.
Plus, implementing Postel's Law to the n-th degree leads to brittle
parsers and easy to attack systems.

There is a school of thought that parsers for large and complex
grammars like SIP should be designed using a language-theoretic
approach since these grammars produce essentially a complex
language.  Such complex grammars are PSPACE-complete, making it
daunting to come up with a bullet-proof parser if we keep on
adding multiple ways to represent similar concepts.

But regardless, I don't mean to hammer on this.  If folks feel that
we need to grandfather "isdn-network", that is fine with me.

Thanks,

- vijay
-- 
Vijay K. Gurbani, Bell Laboratories, Alcatel-Lucent
1960 Lucent Lane, Rm. 9C-533, Naperville, Illinois 60563 (USA)
Email: vkg@{bell-labs.com,acm.org} / vijay.gurbani@alcatel-lucent.com
Web: http://ect.bell-labs.com/who/vkg/  | Calendar: http://goo.gl/x3Ogq

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