Re: [netmod] Long trees RE: Next steps for draft-ietf-netmod-rfc8407bis

[Kent Watsen <[e-mail]>]

It seems that there are two camps:

	1) those that want the tree-diagrams to be as DRY as possible
	2) those that want the tree-diagrams to be as WET as possible

		DRY = Don't Repeat Yourself
		WET = Write Every Time

Tooling can help both cases.

For (1), the tree-diagrams are unexpanded, but surrounding text should point to where each used-grouping is defined.   The better tooling-assisted approach, is for the used groupings *inside the tree-diagram” to become hyperlinks (only possible in supporting formats).   Extending this idea further, hyperlinks could be provided for typedefs and identities too.

For (2), for plain-text and PDF formats, a link to where the image can be accessed would be nice.  For the HTML format, inlining the complete (unfolded) tree-diagram with horizontal-scrolling would be ideal.

Kent


> On Mar 5, 2024, at 3:01 AM, [e-mail] wrote:
> 
> Hi Italo,
>  
> Thanks for sharing your thoughts.
>  
> Please see inline.
>  
> Cheers,
> Med
>  
> De : Italo Busi <[e-mail] <mailto:[e-mail]>>
> Envoyé : lundi 4 mars 2024 19:38
> À : Qin Wu <[e-mail] <mailto:[e-mail]>>; Mahesh Jethanandani <[e-mail] <mailto:[e-mail]>>; BOUCADAIR Mohamed INNOV/NET <[e-mail] <mailto:[e-mail]>>
> Cc : [e-mail] <mailto:[e-mail]>
> Objet : RE: [netmod] Long trees RE: Next steps for draft-ietf-netmod-rfc8407bis
>  
> Hi Med,
>  
> In my personal experience, I have found the YANG tree included in the IETF RFCs/I-Ds useful only when they are complete, even if they are too long
> [Med] I agree that having readily available full trees is useful, however the question is whether it should be embedded in the RFC text or would having stable links to access such trees be much more convenient? Note also that when the tree is too long, there are better places to display them for better user experience (control views, etc.), which we don’t have with the txt version.
>  
> In RFC8795 you can find an example of a too-long YANG tree which I am using quite often
>  
> [Med] If the Datatracker includes a link to the tree or 8795 includes a stable pointer to the full tree without the editing limitations of IETF docs, the experience would be the same, if not better. No?
>  
>  
> I have found YANG trees with unexpanded grouping almost impossible to use. In draft-ietf-teas-yang-te you can find an example of a YANG tree with unexpanded grouping which I am not using at all. In this case, I refer to the YANG catalog to get the complete tree
>  
> [Med] ACK.
>  
> I have also found the YANG tree pieces almost useless (even if much better than the YANG trees with unexpanded grouping) without some overview.
>  
> [Med] Not having an overview to describe the overall structure and help readers navigate among all the various levels is a bug of these specs, IMO. The narrative part of the spec is supposed to help readers digest the structure and zoom in/out when diving into specifics. I think that we need collectively to better explain the rationale of a module design and articulating the various parts of a module. The use of subtrees for too long trees is a means to help structure the description sections.
>  
> RFC8348 is an example of YANG tree pieces which I am using very rarely. In most of the cases, I refer to the YANG catalog to get the complete tree
> [Med] ACK.
>  
> I am wondering whether the issue of YANG tree too-long could be resolved by updating the IETF tooling. For example, I have noted that the html-ized version of the I-Ds is now working well with artwork exceeding the 72 characters limit …
>  
> Maybe the html or html-ized version of the I-D/RFC might include the jstree pyang output instead of the tree pyang output
>  
> [Med] Fully agree that tooling is the way to go here. Having a stable pointer to the tree (including displaying it from the Datatracker metadata) would achieve that objective.
>  
> Back to the txt version, here is an updated version of the reco (for further discussion):
>  
> ==
> NEW:
>    YANG tree diagrams provide a concise representation of a YANG module
>    and SHOULD be included to help readers understand YANG module
>    structure.  If the complete tree diagram for a module becomes long
>    (more than 2 pages, typically), the diagram SHOULD be split into
>    several smaller diagrams (a.k.a subtrees).  For the reader's
>    convenience, a subtree should fit within a page.  If the complete
>    tree diagram is too long (more than 5 pages, typically) even with
>    groupings unexpanded (Section 2.2 of [RFC8340]), the authors SHOULD
>    NOT include it in the document.  A stable pointer to retrieve the
>    full tree MAY be included.
>  
>    The document SHOULD include the following note if the full tree is
>    not included:
>  
>       -- If no stable pointer to retrieve the tree is included
>  
>       The full tree diagram of the module can be generated using,
>       e.g., the "pyang" tool. That tree is not included here because
>       it is too long (Section 3.4 of [RFCXXXX]). Instead, subtrees
>       are provided for the reader's convenience.
>  
>       -- If a stable pointer to retrieve the tree is included
>  
>       The full tree diagram of the module can be retrieved at
>       <stable_url_ref>. That tree is not included here because it is too
>       long (Section 3.4 of [RFCXXXX]). Instead, subtrees are provided
>       for the reader's convenience.
>  
>    These guidelines take precedence over the generic guidance in
>    Section 3 of [RFC8340].
> ==
>  
> My 2 cents
>  
> Italo
>  
> From: Qin Wu <[e-mail] <mailto:[e-mail]>>
> Sent: giovedì 29 febbraio 2024 02:51
> To: Mahesh Jethanandani <[e-mail] <mailto:[e-mail]>>; [e-mail] <mailto:[e-mail]>
> Cc: [e-mail] <mailto:[e-mail]>
> Subject: Re: [netmod] Long trees RE: Next steps for draft-ietf-netmod-rfc8407bis
>  
> +1,  a few thoughts to share.
>  
> I know this is tricky question related to tooling or artifact generation and representation.
> I am wondering whether we can make YANG tree diagram in a "collapsed" state where all the Leaf nodes and only leaf nodes are hidden from view until its parent node is expanded, which can improve readability of the tree diagram,
> In many cases can greatly reduce the size of YANG tree diagram, make it fit into one page.
>  
> Moving compete tree diagram or artifacts is another option we can pursue. Also generating YANG tree along with YANG file inhttps://github.com/YangModels/yang/tree/main/standard/ietf
> Is another option we can take a look at.
>  
> -Qin
> 发件人: netmod [mailto:[e-mail]] 代表 Mahesh Jethanandani
> 发送时间: 2024年2月29日 7:02
> 收件人: [e-mail] <mailto:[e-mail]>
> 抄送: [e-mail] <mailto:[e-mail]>
> 主题: Re: [netmod] Long trees RE: Next steps for draft-ietf-netmod-rfc8407bis
>  
> I would agree with Andy that it is not clear how long is “too long”. 
>  
> BGP YANG model, which is perhaps one of the biggest models at 150 pages long, has multiple tree diagrams none of which are more than one page long.
>  
> If the complete tree diagram is too long, could it moved to the Appendix, instead of banishing it from the document completely? Sorry Jan, but I hope no one is cutting down trees to read the entire tree diagram. Sometimes, albeit rarely, it is helpful to have the complete tree diagram handy to reference where a particular node is in the tree.
>  
> Cheers.
>  
> 
> On Feb 28, 2024, at 8:29 AM, [e-mail] <mailto:[e-mail]> wrote:
>  
> Hi Jan,
>  
> Thanks for the comments.
>  
> Here is a first attempt to address the long trees point while taking into account expanded/unexpanded uses:
>  
> NEW:
>    YANG tree diagrams provide a concise representation of a YANG module
>    and SHOULD be included to help readers understand YANG module
>    structure.  If the complete tree diagram for a module becomes too
>    long, the diagram SHOULD be split into several smaller diagrams.  If
>    the complete tree diagram is too long even with groupings unexpanded
>    (Section 2.2 of [RFC8340]), authors SHOULD NOT include it in the
>    document.
>  
>    These guidelines take precedence over the generic guidance in
>    Section 3 of [RFC8340].
>  
> For convenience a diff for the proposed change can be seenhttps://author-tools.ietf.org/api/iddiff?url_1=https://boucadair.github.io/rfc8407bis/draft-ietf-netmod-rfc8407bis.txt&url_2=https://boucadair.github.io/rfc8407bis/long-trees/draft-ietf-netmod-rfc8407bis.txt
>  
> Cheers,
> Med
>  
> De : Jan Lindblad <[e-mail] <mailto:[e-mail]>> 
> Envoyé : mercredi 28 février 2024 15:21
> À : BOUCADAIR Mohamed INNOV/NET <[e-mail] <mailto:[e-mail]>>
> Cc : [e-mail] <mailto:[e-mail]>
> Objet : Re: [netmod] Next steps for draft-ietf-netmod-rfc8407bis
>  
> Med, author team,
>  
> Thank you for taking the time to get this work done, and well done! This is one of those fundamental bricks that saves time and improves quality for the entire YANG community.
>  
> I read the -09 version and like what I see. I have a couple of minor suggestions you might consider.
>  
> + In section 3.4 about tree diagrams, the section text is already advocating intermixing smaller tree snippets with explanations (which is great), but I wish we could say that 
> tree diagrams of entire modules SHOULD NOT be included. Just a waste of forest and attention span, imho.
>  
> + In section 4.2 about choice of prefixes, it is said that "Prefix values SHOULD be short but are also likely to be unique." I used to say the same thing. In recent years, however, I have started to stress the importance of uniqueness much more. I'd say something like "Prefix values SHOULD be selected carefully to be unique, and ideally not too long." The reason for my change is I have met several engineers who have been deeply confused (to the point of costing real money) when the same prefix has shown up in multiple places. It's just an unnecessary part of the learning curve associated with YANG.
>  
> In fact, I have started to recommend people to set the prefix to equal the module name. This also solves another problem, which is that the "prefixes" you see in RESTCONF are module names, and the confusion of what to use where is sometimes suffocating. I understand if many think I'm going overboard here, but when we pretend that modules don't have prefixes, only module names, there is a lot less friction in learning the ropes.
>  
> + In section 4.6.2 regarding useless (in YANG Context) functions in the XPath function library, it is said that the "YANG compiler" should return false, etc. Better wording might be that the XPath execution environment (or something) should return false, etc. The YANG compiler is not even running when the calls to those functions are happening.
>  
> + In section 4.11.5 regarding booleans, it is said that booleans can take values true and false. This is true in mathematics :-) but in YANG a boolean leaf can additionally take the "value" of "not set". Actually, "not set" is a possibility for leafs in general, unless it is declared mandatory true, or has a default. In my experience, one of the most common YANG modeling issues is when people model a leaf foo, which isn't mandatory, has no default and the description statement does not say what happens if the leaf is not set. In many cases, there is a sort of natural meaning, but with booleans leafs in particular, the absence of the leaf is typically highly ambiguous. I think this hole merits a recommendation clause in the I-D.
>  
> Best Regards,
> /jan
>  
>  
>  
> 
> On 28 Feb 2024, at 10:51, [e-mail] <mailto:[e-mail]> wrote:
>  
> Hi all, 
> 
> I think that this version is ready for the WGLC.
> 
> The document fully covers the items promised when requesting adoption [1]. As listed in the ACK section, we also solicited and integrated feedback from many yangdoctors, solicited SAAG WG to review the security text, etc. Refer to 1.1 for a comprehensive list of the changes.
> 
> Cheers,
> Med
> 
> [1] Slide#7 of https://datatracker.ietf.org/meeting/117/materials/slides-117-netmod-7-guidelines-for-authors-and-reviewers-of-documents-containing-yang-data-models-00 
> 
> 
> -----Message d'origine-----
> De : I-D-Announce <[e-mail] <mailto:[e-mail]>> De la part de
> [e-mail] <mailto:[e-mail]>
> Envoyé : mercredi 28 février 2024 10:01
> À : [e-mail] <mailto:[e-mail]>
> Cc : [e-mail] <mailto:[e-mail]>
> Objet : I-D Action: draft-ietf-netmod-rfc8407bis-09.txt
> 
> Internet-Draft draft-ietf-netmod-rfc8407bis-09.txt is now available.
> It is a work item of the Network Modeling (NETMOD) WG of the IETF.
> 
>   Title:   Guidelines for Authors and Reviewers of Documents
> Containing YANG Data Models
>   Authors: Andy Bierman
>            Mohamed Boucadair
>            Qin Wu
>   Name:    draft-ietf-netmod-rfc8407bis-09.txt
>   Pages:   84
>   Dates:   2024-02-28
> 
> Abstract:
> 
>   This memo provides guidelines for authors and reviewers of
>   specifications containing YANG modules, including IANA-maintained
>   modules.  Recommendations and procedures are defined, which are
>   intended to increase interoperability and usability of Network
>   Configuration Protocol (NETCONF) and RESTCONF protocol
>   implementations that utilize YANG modules.  This document obsoletes
>   RFC 8407.
> 
>   Also, this document updates RFC 8126 by providing additional
>   guidelines for writing the IANA considerations for RFCs that
> specify
>   IANA-maintained modules.
> 
> The IETF datatracker status page for this Internet-Draft is:
> https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdata <https://data/>
> tracker.ietf.org <http://tracker.ietf.org/>%2Fdoc%2Fdraft-ietf-netmod-
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> 30c943a5a4c608dc383bce6b%7C90c7a20af34b40bfbc48b9253b6f5d20%7C0%7C0%7C
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> P9v5QurysF69syyEyba9yYss7xd7K5E2FE%3D&reserved=0
> 
> There is also an HTML version available at:
> https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww <https://www/>.
> ietf.org <http://ietf.org/>%2Farchive%2Fid%2Fdraft-ietf-netmod-rfc8407bis-
> 09.html&data=05%7C02%7Cmohamed.boucadair%40orange.com <http://40orange.com/>%7C5167223130c943
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> 
> A diff from the previous version is available at:
> https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fauth <https://auth/>
> or-tools.ietf.org <http://or-tools.ietf.org/>%2Fiddiff%3Furl2%3Ddraft-ietf-netmod-rfc8407bis-
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> JBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=zo%2FrtFJrYJkJXOceIpzR
> mlGAQF2c8m9Z%2F0vShl5o8gQ%3D&reserved=0
> 
> Internet-Drafts are also available by rsync at:
> rsync.ietf.org <http://rsync.ietf.org/>::internet-drafts
> 
> 
> 
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>  
> 
> Mahesh Jethanandani
> [e-mail] <mailto:[e-mail]>
>  
>  
>  
>  
> 
>  
> ____________________________________________________________________________________________________________
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