Re: [Gen-art] Gen-ART review of draft-ietf-dime-app-design-guide-19

[Martin Thomson <[e-mail]>]

I just read through the diff of -24.  I'm assuming that my feedback
was lost somewhere.

On 14 September 2013 09:41, Jouni Korhonen <[e-mail]> wrote:
> Martin,
>
> Thanks for the detailed review. I'll let the authors respond to these if they
> have further questions or clarifications to ask.
>
> - Jouni
>
>
>
> On Sep 14, 2013, at 3:13 AM, Martin Thomson <[e-mail]> wrote:
>
>> I am the assigned Gen-ART reviewer for this draft. For background on
>> Gen-ART, please see the FAQ at
>>
>> <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
>>
>> Please resolve these comments along with any other Last Call comments
>> you may receive.
>>
>> Document: draft-ietf-dime-app-design-guide-19
>> Reviewer: Martin Thomson
>> Review Date: 2013-09-13
>> IETF LC End Date: unknown, early review
>> IESG Telechat date: (if known)
>>
>> Summary: This document is ready, with some minor issues and nits.
>>
>> Minor issues:
>> I would find it a lot easier to read this document if it did as the
>> goals state (the first objective from the introduction) and clarify
>> what the extensibility rules in Diameter say with respect to each of
>> the described extensions.  It's not easy to glean this information
>> from RFC 6733, which makes reviewing this a little tricky.
>>
>> For instance, Section 4.1 doesn't really say what the expectations are
>> with respect to implementations that receive unknown or unsupported
>> commands.  I think that I could guess, but I'd rather not.  (I just
>> read the relevant parts of 6733, and it turns out that my guess was
>> wrong.)
>>
>> The same applies to Section 4.2, presumably through applying the same
>> principles.  The question here is: what would be the expected behavior
>> if a node was operating on the new application definition and that
>> node received a deleted command?  (The old implementation presumably
>> has no problem with the absence of the command if it's being removed.)
>>
>> The same applies to Section 5.
>>
>> Sections 4.4.2 and particularly 5.6 lead me to infer that the
>> extensibility for enumerated types is fundamentally broken, so maybe
>> those properties need to be expanded upon a little here too.
>>
>> The placement of the guidance in Section 5.6 seems fairly important
>> for Section 4, lest that important information be lost to someone just
>> looking to tweak a command.
>>
>> Section 4.3.1, perhaps add to the M-bit criteria: Would the presence
>> or value of the AVP alter the interpretation of the command (or any
>> other AVP) in any way?  (nit: s/AVPs/AVP on second bullet here.)
>>
>> I didn't find the list in  Section 6 particularly compelling.  It
>> seemed a little like motherhood statements.  The description of what
>> it was this was talking about: good; the description of how these
>> "often" (always?) manifest is also useful.  I wonder though whether
>> it's safe to generalize when you only see generic protocols extensions
>> as optional AVPs.  Perhaps you need to refocus on exactly that, and
>> leave the other forms of extension to speculation.
>>
>> Nits/editorial comments:
>> The last paragraph of Section 3 is confusing to me.  Firstly, the
>> subject of the reminder is missing from the first sentence.  I think
>> that the intent of that sentence is to say that extending by adding
>> applications or commands is to be avoided, but then subsequent
>> sentences make it clear that doing so is easy.  The last sentence
>> seems to be talking about something else entirely, which is the value
>> that IANA registries provide.  I am going to have to suggest that this
>> be reworded entirely.
>>
>> In Section 4.1, I'd like to see the note turned into real text.  The
>> size and complexity of an application seems to be a fairly significant
>> factor in determining whether a new application imports commands, or
>> whether separate applications are defined.
>>
>> I read the first bullet in Section 4.3.2 as a sentence, several times,
>> before realizing that it's a title.  Please reconsider the formatting
>> of this list.  At a very minimum, remove the period.
>>
>> --Martin
>>
>> p.s., I'm on vacation starting approximately ...now, since I'm out of
>> time for this review... so apologies for any slow responses to the
>> review.
>