Re: [netmod] Reminder: WGLC - draft-ietf-netmod-yang-tree-diagrams

Robert Wilton <> Mon, 15 January 2018 15:07 UTC

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To: Martin Bjorklund <>
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From: Robert Wilton <>
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Date: Mon, 15 Jan 2018 15:07:22 +0000
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Subject: Re: [netmod] Reminder: WGLC - draft-ietf-netmod-yang-tree-diagrams
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Hi Martin,

All OK with me except where I have further comments/questions inline below:

On 15/01/2018 14:39, Martin Bjorklund wrote:
> Hi,
> Thanks for the review!  Comments inline.
> Robert Wilton <> wrote:
>> Hi Lou, Martin
>> I've done a quick review of draft -04.
>> It looks well written to me.
>> I have a spotted a few minor nits/questions.
>> Section 1:
>> (i) "Such diagrams are commonly used to provided " => "Such diagrams
>> are used to provide"?
> Ok.
>> (ii) "This document provides the syntax used in YANG Tree Diagrams."
>> => "This document describes the syntax used in YANG Tree Diagrams", or
>> if not "describes", perhaps "specifies"?
> I changed to "describes".
>> (iii) "common practice is include" => "common practice is to include"
> Ok.
>> Section 2:
>> (iv) Are the top level data nodes really offset by 4 spaces, or should
>> this be 2 spaces?  The example in section 2, and section 4 seem to
>> differ here.  The submodule example in Sec 2.1 looks like it is using
>> 2 spaces.
> It should be 4 spaces.  I fixed the example in 2.1.
Hum, OK.  Is this the right choice?
  - It means that the tree is indented 2 spaces further than everything 
else (e.g. groupings, augments, etc).
  - YANG modules in RFC's already struggle with line length anyway, 
hence wouldn't the use of 2 spaces give the model a bit more space.

I also think that it would be good to check the indent of all the tree 
diagram snippets in the doc, it looks like they may be using somewhat 
varying levels of indents (between 2 and 6 spaces).

>> (v) "is prefaces with" => "is prefaced with"
> Ok.
>> (vi) Section 2.2, should there be an example of an unexpanded uses
>> statement?  I was wondering if this section was under specified?
> I have added:
>     For example, the following diagram shows the "tls-transport" grouping
>     from [RFC7407] unexpanded:
>         +--rw tls
>            +---u tls-transport
>     If the grouping is expanded, it could be printed as:
>         +--rw tls
>            +--rw port?                 inet:port-number
>            +--rw client-fingerprint?   x509c2n:tls-fingerprint
>            +--rw server-fingerprint?   x509c2n:tls-fingerprint
>            +--rw server-identity?      snmp:admin-string
Yes, looks good.

>> Section 2.6:
>> (vii) "If the node is augmented into the tree from another module, its
>> name is printed as <prefix>:<name>."  Does there need to be a
>> clarification that the prefix name used is the one used by the
>> module's import statement?  Or does it use the prefix statement from
>> the imported modules instead (I know that these should normally be the
>> same, but this is not guaranteed).
> Since this is used when a node is augmented *into* the main tree, it
> can't be the prefix in import, since the augmenting module is not
> imported from the augmented module.  I did:
But the YANG module must import the module that it is augmenting. If a 
local import prefix is used in the actual YANG module then it would be 
slightly harder to relate the tree output back to local import prefixes 
used in the YANG module.

> OLD:
>        If the node is augmented into the tree from another module,
>        its name is printed as <prefix>:<name>.
> NEW:
>        If the node is augmented into the tree from another module,
>        its name is printed as <prefix>:<name>, where <prefix> is the
>        prefix defined in the module where the node is defined.
This is OK with me, but there is still a potential for a prefix 
namespace clash (since prefixes are not guaranteed to be unique).

An alternative solution would be for the YANG tree diagram to list (at 
the beginning or the end of the diagram) the mappings from prefix -> 
module name used.  This has the bonus that it also explicitly lists the 
YANG modules that are being augmented, but conversely, this might end up 
just adding unnecessary noise to a diagram that should be short and 
simple ...

A second alternative would be to add some vague text to state that the 
prefix to module mapping should be explicitly listed in any cases where 
the prefix name alone is not obvious.


>> Section 3.2.
>> (viii) It would be slightly easier to read if there wasn't a linebreak
>> between "--" and "tree-print-groupings", not sure if that is feasible
>> to force this.
> I don't think I can enforce this, but I'll look into it.  If nothing
> else, the RFC editor will fix this.
> /martin
>> Thanks,
>> Rob
>> On 10/01/2018 16:16, joel jaeggli wrote:
>>> Just a reminder given the date that this was posted. This last call is
>>> expected to complete Monday 1/15/18.
>>> Thanks
>>> joel
>>> On 1/1/18 2:01 PM, joel jaeggli wrote:
>>>> Greetings,
>>>> We hope  the new year is a time to make great progess on outstanding
>>>> documents before preparation for the  London IETF begins in earnest.
>>>> This starts a two-week working group last call on:
>>>>    YANG Tree Diagrams
>>>> draft-ietf-netmod-yang-tree-diagrams
>>>> Please send email to the list indicating your support or concerns.
>>>> We are particularly interested in statements of the form:
>>>>     * I have reviewed this draft and found no issues.
>>>>     * I have reviewed this draft and found the following issues: ...
>>>> Thank you,
>>>> NETMOD WG Chairs
>>> _______________________________________________
>>> netmod mailing list
>>> .
> .