Subject: Re: [netmod] I-D Action: draft-ietf-netmod-rfc6087bis-04.txt

From: Jernej Tuljak <[email-masked]>
Date: Mon, 14 Sep 2015 12:56:48 +0200

Hi,

current text in 6087bis-04 (Section 5.6.4):

    XPath expressions for 'when' statements SHOULD NOT reference the
    context node or any descendant nodes of the context node.  They MAY
    reference descendant nodes if the 'when' statement is contained
    within an 'augment' statement, and the referenced nodes are not
    defined within the 'augment' statement.

This is OK. But the text never mentions an analogous case, which is when 
a when-stmt is defined for a uses-stmt. I think this should be 
corrected. Note that finding the initial context node for the expression 
uses an algorithm that is virtually equal to the 'augment' case (first 
data node ancestor), therefore the first sentence in the above text 
discourages use of 'when' statements within a 'uses' statement, which I 
don't think was the intention.

   grouping special-params {
     leaf param1 {
       type string;
     }
     leaf param2 {
       type string;
     }
   }

   container foo {
     leaf enable-special {
       type boolean;
     }
     uses special-params {
       when "enable-special = 'true'";
     }
   }

In my example the expression references a descendant of the initial 
context node, which should be OK. What would be problematic is 
referencing descendants that are defined in the grouping.

OLD:

    XPath expressions for 'when' statements SHOULD NOT reference the
    context node or any descendant nodes of the context node.  They MAY
    reference descendant nodes if the 'when' statement is contained
    within an 'augment' statement, and the referenced nodes are not
    defined within the 'augment' statement.

NEW:

    XPath expressions for 'when' statements SHOULD NOT reference the
    context node or any descendant nodes of the context node.  They MAY
    reference descendant nodes if the 'when' statement is contained
    within an 'augment' statement, and the referenced nodes are not
    defined within the 'augment' statement. They MAY also reference
    descendant nodes if the 'when' statement is contained within a
    'uses' statement, and the referenced nodes are not defined within
    the 'grouping' statement being referred to by the 'uses' statement.

Or something similar.

Jernej

[email-masked] je 6.7.2015 ob 19:14 napisal:
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>   This draft is a work item of the NETCONF Data Modeling Language Working Group of the IETF.
>
>          Title           : Guidelines for Authors and Reviewers of YANG Data Model Documents
>          Author          : Andy Bierman
> 	Filename        : draft-ietf-netmod-rfc6087bis-04.txt
> 	Pages           : 52
> 	Date            : 2015-07-06
>
> Abstract:
>     This memo provides guidelines for authors and reviewers of Standards
>     Track specifications containing YANG data model modules.  Applicable
>     portions may be used as a basis for reviews of other YANG data model
>     documents.  Recommendations and procedures are defined, which are
>     intended to increase interoperability and usability of Network
>     Configuration Protocol (NETCONF) implementations that utilize YANG
>     data model modules.
>
>
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-ietf-netmod-rfc6087bis/
>
> There's also a htmlized version available at:
> https://tools.ietf.org/html/draft-ietf-netmod-rfc6087bis-04
>
> A diff from the previous version is available at:
> https://www.ietf.org/rfcdiff?url2=draft-ietf-netmod-rfc6087bis-04
>
>
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>
> _______________________________________________
> netmod mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/netmod
>

---

From: Ladislav Lhotka <[email-masked]>
Date: Tue, 15 Sep 2015 10:09:07 +0200

>     the 'grouping' statement being referred to by the 'uses' statement.

+1

Lada

-- 
Ladislav Lhotka, CZ.NIC Labs
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