Re: [netmod] Fwd: New Version Notification for draft-lengyel-netmod-yang-instance-data-01.txt

Robert Wilton <> Wed, 13 June 2018 14:40 UTC

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To: Balazs Lengyel <>, "" <>
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From: Robert Wilton <>
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Date: Wed, 13 Jun 2018 15:40:31 +0100
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Subject: Re: [netmod] Fwd: New Version Notification for draft-lengyel-netmod-yang-instance-data-01.txt
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I would support this draft (if/when a call for adoption is made).

A few comments from a quick review :

1) I think that it would be useful to allow a file to contain multiple 
"instance data sets".  I could easily imagine that multiple different 
blocks of instance data may need to be provided and allowing these to be 
carried within a single file seems helpful.

2) I wonder whether these instance-data blocks could be used to hold 
examples in drafts/RFCs.  It would be nice if the examples could be 
automatically extracted and validated.  Possibly this draft could help 
with this, although I appreciate it is not its main focus.

3) Possibly a comment should be made about whitespace, although I think 
that it is fairly obvious how whitespace would be handled, i.e. as 
defined by the encoding.

4) "YANG instance data files SHOULD be used to provide design time 
information about server capabilities." sounds quite strong. I think 
that this should either be a MAY, or the sentence should be predicated.  
E.g . "If the server provides design time information about server 
capabilities then YANG instance data files SHOULD be used to allow them 
to be easily read and consumed by clients"

5) I'm wondering whether there needs to be some sort of identifier about 
what type data is held.  E.g. does it represent data that can be 
consumed as part of one of the configuration datastores, or does it 
represent the equivalent of operational state, or is it data for an RPC, 

6) If this data is to be stored in a file, should it state that it must 
be stored as UTF-8 character encoding?

7) It might want to include a semantic version number for an 
instance-data-set, depending on whether the YANG versioning discussions 
ends up.


On 13/06/2018 15:06, Balazs Lengyel wrote:
> Hello,
> I submitted a new version of the yang-instance-data draft updated with 
> comments from the last IETF and others. I would like to get this 
> adopted as a workgroup item. Please review it and if you like it 
> please indicate that you support it as a workgroup item.
> Changes:
>    o  Redefined using yang-data-ext
>    o  Moved meta data into ordinary leafs/leaf-lists
>    o  Corrections, clarifications
> regards Balazs
> -------- Forwarded Message --------
> Subject: 	New Version Notification for 
> draft-lengyel-netmod-yang-instance-data-01.txt
> Date: 	Wed, 13 Jun 2018 06:47:16 -0700
> From:
> To: 	Benoit Claise <>om>, Balazs Lengyel 
> <>
> A new version of I-D, draft-lengyel-netmod-yang-instance-data-01.txt
> has been successfully submitted by Balazs Lengyel and posted to the
> IETF repository.
> Name:		draft-lengyel-netmod-yang-instance-data
> Revision:	01
> Title:		YANG Instance Data Files and their use for Documenting Server Capabilities
> Document date:	2018-06-13
> Group:		Individual Submission
> Pages:		10
> URL:
> Status:
> Htmlized:
> Htmlized:
> Diff:
> Abstract:
>     This document specifies a standard file format for YANG instance
>     data, that is data that could be stored in a datastore and whose
>     syntax and semantics is defined by YANG models.  Instance data files
>     can be used to provide information that is defined in design time.
>     There is a need to document Server capabilities (which are often
>     specified in design time), which should be done using instance data
>     files.
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at
> The IETF Secretariat
> -- 
> Balazs Lengyel                       Ericsson Hungary Ltd.
> Senior Specialist
> Mobile: +36-70-330-7909      
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