Re: [netmod] instance data new backward compatibility text

Martin Bjorklund <mbj@tail-f.com> Tue, 26 March 2019 10:53 UTC

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Date: Tue, 26 Mar 2019 11:53:03 +0100 (CET)
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To: j.schoenwaelder@jacobs-university.de
Cc: balazs.lengyel@ericsson.com, netmod@ietf.org
From: Martin Bjorklund <mbj@tail-f.com>
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Subject: Re: [netmod] instance data new backward compatibility text
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Hi

I agree with Juergen.  I think section 6 should be removed.  This
document should specify the document format (which it does), but it
shouldn't specify specific rules for the different use cases.


/martin


Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> wrote:
> Your rules are use case specific and I am not convinced they are
> applying to all use cases. It should be a perfectly valid use case to
> store snapshots of <running> in instance data files. Your rules do not
> make sense here and I do not think this is a valid usage of the SHOULD
> mechanism.
> 
> /js
> 
> On Mon, Mar 25, 2019 at 11:01:52PM +0000, Balázs Lengyel wrote:
> >    Hello Jurgen,
> > 
> >    I don't think these rules are Ericsson specific. In some of our most
> >    important use-cases (UC1, UC2, UC6) changing the keys would lead to
> >    problems.
> > 
> >    UC1: If you document server capabilities using ietf-yang-library the name
> >    of the module sets may be/should be meaningful. It might be used by the
> >    NMS to compare the capabilities of different versions of the YANG server;
> >    changing keys without a reason will mislead the NMS into assuming the
> >    server capabilities changed..
> > 
> >    UC2: Preloading default configuration data. E.g. If you change the
> >    identifier of NACM ruleset, then during upgrade it might be loaded again
> >    as the server can not detect, that this is the same ruleset that is
> >    already in the datastore.
> > 
> >    UC6:Â Storing diagnostics data. If you change the keys used in diagnostic
> >    data, comparing values before and after the key change will be difficult.
> > 
> >    And yes as we were using instance data for the last then years, we did
> >    have a lot of problem with people changing the keys without considering
> >    compatibility effects.
> >    I agree that this is not always a problem, so I only used SHOULDÂ (and not
> >    MUST) in the text.
> > 
> >    regards Balazs
> > 
> > 
> >    On 2019. 03. 25. 23:16, Juergen Schoenwaelder wrote:
> > 
> >  On Mon, Mar 25, 2019 at 09:59:43PM +0000, Balázs Lengyel wrote:
> > 
> >  Hello Jurgen,
> > 
> >  You are right that this is important mostly for instance data prepared as a
> >  design/implementation activity; while not relevant for data coming from the
> >  node.
> >  I will add it.
> > 
> >  However in the first case it is vital!
> > 
> >  For config files, and also for file documenting server capabilities we have
> >  had MANY problems with people changing the key values/identities of list
> >  entries.
> >  They think it is a nice idea to provide better, more meaningful key values;
> >  however the NMS designers use these key values to detect changes; also
> >  during an upgrade process if a default configuration file is loaded again
> >  with slightly changed key values, then e.g. access control rules become
> >  duplicated.
> > 
> > 
> >  The conditions under which it is meaningful to change keys and when it
> >  is not appropriate are very application specific.  You may have
> >  specific use cases at Ericsson where you want internal regulations but
> >  I do not think this leads to meaningful rules outside your specific
> >  application scenario.
> > 
> >  /js
> > 
> > 
> >  --
> >  Balazs Lengyel                       Ericsson Hungary Ltd.
> >  Senior Specialist
> >  Mobile: +36-70-330-7909              email: [1]Balazs.Lengyel@ericsson..com
> > 
> > References
> > 
> >    Visible links
> >    1. mailto:Balazs.Lengyel@ericsson.com
> 
> 
> 
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> > netmod@ietf.org
> > https://www.ietf.org/mailman/listinfo/netmod
> 
> 
> -- 
> Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
> Fax:   +49 421 200 3103         <https://www.jacobs-university.de/>
>