Re: DRAFT Montreal minutes - X#NodeArchitecture comments

[Paul Koning <pkoning@xxxxxxxxxxxxxx>]

>>>>> "William" == William Studenmund <wrstuden@xxxxxxxxxxxxxxxxx> writes:

 William> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1

 William> On Aug 17, 2006, at 6:43 AM, Paul Koning wrote:

 >> A good way to fix this is to add two rules:
 >> 
 >> 1. If a key is not understood, it is assumed to be a negotiation
 >> key (and a NotUnderstood reply must be sent).  2. If a declarative
 >> key is sent, and a reply is received from the other end with that
 >> key and a value of NotUnderstood, this is a protocol violation
 >> only if the key is required to be implemented.  If it was not
 >> required (i.e., X# keys) then a NotUnderstood reply must be
 >> silently ignored.

 William> I like the proposed fix. The two comments I have are:

 William> 1) While X# keys are not required to be understood, any
 William> future "normal" keys we define will also fall into this
 William> category for existing devices.

True.  So replace "i.e." by "e.g.".

 William> 2) I note that a device may chose to pretend it doesn't
 William> understand a key that isn't mandatory, even though it really
 William> does. For X#NodeArchitecture, a device may answer with
 William> differing levels of detail. The lowest level may well be to
 William> pretend that the key's not understood. In such a case, the
 William> device MUST fully pretend it doesn't understand, and as per
 William> rule (1) above, it MUST not offer the key and MUST respond
 William> with "NotUnderstood."

 William> Note: this is a different behavior from understanding
 William> X#NodeArchitecture and choosing not to declare a value to
 William> the other side.

I'm not sure whether that is a distinction without a difference.  Does
it matter whether you can do that?  Do we need any extra text to make
it legal to do that?  I don't think so; if a key is optional then not
implementing it is allowed.  "Not implementing" may be a runtime
choice, not just a design-time choice.

If we do need that text for X#NodeArchitecture, it belongs in the
spec for that key, it isn't part of the 3720 fix.

     paul


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