Subject: [netmod] review of draft-ietf-netmod-yang-tree-diagrams-02

From: Juergen Schoenwaelder <[email-masked]>
Date: Sun, 29 Oct 2017 19:50:57 +0100

Hi,

I have reviewed draft-ietf-netmod-yang-tree-diagrams-02 and here are
my comments (in document order).

- I am not sure this is correct:

  YANG Tree Diagrams were first published in [RFC7223].  Such diagrams

  I think NACM (RFC 6536) already has a tree diagram. This makes for a
  difference of ~2 years. Note sure this matter much however.

- Do we have to speak more specifically about 'schema tree diagrams'?
  Note that there can be many more 'tree' diagrams, like instance tree
  diagrams, identity derivation diagrams, type derivation diagrams,
  import relationship diagrams, ... and perhaps it makes sense to
  allow for other diagrams to be defined over time.

- Should we use 'sibling nodes' instead of 'peer nodes'? I think
  the term 'sibling' is used in RFC 7950.

- Are the empty lines mandatory or can empty lines added as one sees
  fit? In particular, is there an empty line after the module: line?
  Is there an empty line before each section of different top-level
  symbols? Does the order of top-level symbols matter? Do we really
  want to specify these details? Well, for indentation, things are
  pretty specific so I wonder what the general strategy is here.

- There was already some discussion about having a way to not always
  expand groupings by showing uses nodes. I think this makes sense in
  certain situations (possible <flags> '-u').

- What are 'data modules'? This term does not appear in schema mount
  I think. Perhaps you wanted YANG modules instead?

- s/realted/related/

- I think Section 4.1 is not about representing _instance_ data
  trees. It is describing how a schema mounted schema looks like - and
  I think this is OK. I think this document should not specify
  instance tree formats. So change the title of section 4.1 or simply
  delete the subsection title entirely.

- If a schema mount point is used for a readonly mount, then I
  understand that only the toplevel changes to ro. Is this useful or
  potentially misleading? Was the alternative considered to change all
  nodes recursively to ro? I assume they are all effectively ro in
  this case.

- If the WG wants to include tree diagram usage guidelines in this
  document, then I think we should (if we still manage) take tree
  diagram related text out of 6087bis before it is cast into
  stone. Changes to 6087bis would be:

  - Change the subsubstitle "2.5.1.  YANG Tree Diagrams" to "2.6.
    YANG Tree Diagrams" (since the definition is in an external
    document, I think this should not be nested in 2.5 anymore).

  - Remove section 3.4.

  - Remove this from section 8 (which is not quite correct anymore
    anyway since the definition moved to a separate document).

       o  Added YANG tree diagram definition and guideline

  Since two are bug fixes anyway (I think), I think it makes sense to
  get 6087bis fixed so that the tree diagram usage text is in one
  place.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>

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From: Martin Bjorklund <[email-masked]>
Date: Mon, 30 Oct 2017 15:36:56 +0100 (CET)

Hi,

Thank you for this review!  Comments inline.

>   difference of ~2 years. Note sure this matter much however.

I'll fix this.

>   allow for other diagrams to be defined over time.

I agree that there can be different types of tree.  I have to think
about this and discuss with my co-author.

>   the term 'sibling' is used in RFC 7950.

Yes.

>   pretty specific so I wonder what the general strategy is here.

For indentation, spaces a specified b/c they matter (ok, we *could*
specify some more flexible indentation rules).  Blank line do not
matter.  Do you think we should say something about this?

>   certain situations (possible <flags> '-u').

Ok, I also think we should add something like this.

>   I think. Perhaps you wanted YANG modules instead?

Yes.

> - s/realted/related/

Fixed.

>   delete the subsection title entirely.

I agree.  How about "Representation of Mounted Data Trees"?

>   nodes recursively to ro? I assume they are all effectively ro in

Hmm, I'll check w/ my co-author.  I think it should be changed
recursively.

>   get 6087bis fixed so that the tree diagram usage text is in one

I have no strong opinion, but I think I prefer to have the guidelines
for tree diagrams in the tree diagram draft.  Maybe 6087 can point to
this document.

/martin

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From: Lou Berger <[email-masked]>
Date: Mon, 30 Oct 2017 10:50:11 -0400

Hi,

See below.

> about this and discuss with my co-author.

We can discuss off line then get back to the wg- we can try to cover this 
in our ietf100 slot.

>>   the term 'sibling' is used in RFC 7950.
Wfm.

> Ok, I also think we should add something like this.

No objections.

>>   I think. Perhaps you wanted YANG modules instead?
Thanks.

> I agree.  How about "Representation of Mounted Data Trees"?

Wfm.

> Hmm, I'll check w/ my co-author.  I think it should be changed

I think this is a good improvement.

> for tree diagrams in the tree diagram draft.  Maybe 6087 can point to

I agree.

Thanks,
Lou
Co-author
>
> /martin
>
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> https://www.ietf.org/mailman/listinfo/netmod
>

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From: Juergen Schoenwaelder <[email-masked]>
Date: Mon, 30 Oct 2017 16:05:56 +0100

> matter.  Do you think we should say something about this?

I would hope that nobody ever comes up with the idea of writing
programs to parse tree diagrams, hence I am fine with a rather liberal
definition (and I also do not care about the exact number of spaces
but I if it helps to describe the indentation rules then OK).

> I agree.  How about "Representation of Mounted Data Trees"?

Isn't is a mounted schema tree?

> for tree diagrams in the tree diagram draft.  Maybe 6087 can point to

RFC 6087bis would still point to the tree diagram if you apply the
edits above but it would no do anything more than that.

/js

---

From: Martin Bjorklund <[email-masked]>
Date: Mon, 30 Oct 2017 16:09:29 +0100 (CET)

> Isn't is a mounted schema tree?

Whoops, yes:   "Representation of Mounted Schema Trees".

> edits above but it would no do anything more than that.

Ok.

/martin