Re: [netmod] OpsState Direction Impact on Recommended IETF YANG Model Structure

[Robert Wilton <[e-mail]>]

On 15/07/2016 15:16, Acee Lindem (acee) wrote:
>
> On 7/14/16, 4:00 PM, "Kent Watsen" <[e-mail]> wrote:
>
>> [This thread took on a life of its own, so I’m replying to this email
> >from two days ago]
>> I had assumed the plan/recommendation would be:
>>   - for works-in-progress, to evaluate if their models can be improved.
>>   - for existing RFCs, do nothing (though we may want to consider
>> RFC7223).
>>
>> By “if their models can be improved” in the above, I’m implying that
>> having a top-level -state branch may still be the best solution for some
>> models.  It’s up to each model designer to decide the best approach for
>> their models.
>>
>> Makes sense?
> I think the statement “if their models can be improved” leaves too much
> subjectivity in the guideline. Either we are going to avail the revised
> data store model to avoid duplication of YANG schema nodes or we are going
> to leverage the new data stores solely to meet the intended/applied config
> requirement. If it is the latter and a good portion of the network devices
> will not support, then I would agree.
Devices can still leverage the new operational state datastore (and 
hence allow foo and foo-state to be merged) without having to supporting 
an intended/applied configuration split (i.e. they just treat applied = 
intended).

I'm keen to get the models simpler were possible because I think that 
will help with their longevity and ease of use.

Thanks,
Rob


>
>
>
>
>> Kent  // as a contributor
>>
>>
>> On 7/12/16, 11:23 AM, "netmod on behalf of Lou Berger"
>> <[e-mail] on behalf of [e-mail]> wrote:
>>
>> Acee,
>>
>>     I personally was assuming we'd follow 3, but I'd like to understand
>> the implication of 2 as I'm not sure I really understand what you're
>> thinking here.  Can you elaborate what you're thinking here?
>>
>> Thanks,
>>
>> Lou
>>
>> On 7/11/2016 12:36 PM, Acee Lindem (acee) wrote:
>>> While there are details to be worked out between the two data stores
>>> models (as indicated below), we now have implicit modeling of applied
>>> configuration. Existing models (both standard and draft) do not take
>>> this
>>> into consideration and, consequently, much of the state that is modeled
>>> explicitly represents the application configuration. For the RFC models,
>>> it probably doesn’t make much sense to redo them (unless they are being
>>> reworked for other reasons). This still leaves the existing WG draft
>>> models for which we have basically 3 options:
>>>
>>>    1. Do nothing - allow them proceed as they are with multiple ways of
>>> representing the applied configuration. This would provide visibility to
>>> the data independent of whether or not the device supported the revised
>>> data-stores supporting implicit retrieval of the applied configuration.
>>>    2. Prune out the redundant data nodes except those required as list
>>> keys, etc, since they can be obtained from the applied state data store.
>>>    3. #2 plus collapse the config (read-write) and  system-state
>>> (read-only) into common containers. No more branching of
>>> <model-name>-config and <model-name>-state at the top level of the
>>> model.
>>>
>>> At I high-level, I feel these are the options. I’m not married to any
>>> one
>>> of these and the worse thing we could do is hold up progression of the
>>> existing YANG model drafts for another couple years while we debate the
>>> best course. Having said that, #3 is compelling since it will yield the
>>> most concise models and colocates the schema data nodes for any managed
>>> object.
>>>
>>> Thanks,
>>> Acee
>>>
>>> On 7/1/16, 12:36 PM, "netmod on behalf of Lou Berger"
>>> <[e-mail] on behalf of [e-mail]> wrote:
>>>
>>>> All,
>>>>
>>>> It's time to make a consensus call on this topic, so that we can all
>>>> move
>>>> on to defining a solution and aligning modules under development. Based
>>>> on the feedback received and the overall discussions on the topic, we
>>>> see
>>>> that there is consensus to follow a datastore based approach to
>>>> supporting operational state, i.e., direction 'B'.
>>>>
>>>> We will be asking the authors of [4] and [5] to review their proposals
>>>> (individual drafts) in Berlin, as well as to highlight differences and
>>>> suggest ways that their work could be consolidated. Of course, others
>>>> may
>>>> also choose to submit their own proposals. Given the importance of this
>>>> work, we will be looking to have active discussion on the topic both in
>>>> Berlin and on the list, with an objective of having a draft ready for
>>>> considerations as a WG document by the November IETF.
>>>>
>>>> We have reviewed this decision with our AD and the NetConf chairs and
>>>> have agreed to begin this work in NetMod. We certainly expect to
>>>> coordinate the work with the NetConf WG and re-home work as/if needed.
>>>>
>>>> Finally, we'd also like to thank all those who have contributed to this
>>>> discussion to date, from problem identification to proposed solutions,
>>>> and we look forward to your continued efforts to publish a standard
>>>> solution.
>>>>
>>>> Lou (and Kent)
>>>>
>>>>
>>>> On 6/7/2016 10:19 AM, Lou Berger wrote:
>>>>> All,
>>>>>
>>>>> We want to provide an update based on the off line discussions
>>>>> related to OpState Solutions that we have been having and solicit
>>>>> input from the WG.
>>>>>
>>>>> All authors of current solution drafts [1,2,3] together with those
>>>>> who helped conduct the solutions analysis* were invited to the these
>>>>> discussions -- with the objective of coming up with a single
>>>>> consolidated proposal to bring to the WG. (I/Lou acted as facilitator
>>>>> as Kent and Juergen were and are involved with the technical details.)
>>>>>
>>>>> The discussions have yielded some results but, unfortunately,
>>>>> not a single consolidated proposal as hoped, but rather two
>>>>> alternate directions -- and clearly we need to choose one:
>>>>>
>>>>>      1) Adopt the conventions for representing state/config
>>>>>         based on Section 6 of [1].
>>>>>
>>>>>         From a model definition perspective, these conventions
>>>>>         impact every model and every model writer.
>>>>>
>>>>>      2) Model OpState using a revised logical datastore definition
>>>>>         as introduced in [4] and also covered in [5]. There is
>>>>>         also a variant of this that we believe doesn't significantly
>>>>>         impact this choice.
>>>>>
>>>>>         With this approach, model definitions need no explicit
>>>>>         changes to support applied configuration.
>>>>>
>>>>> >From a technology/WG standpoint, we believe an approach
>>>>> that doesn't impact every model written (i.e., #2) is superior.
>>>>> The counterpoint to this is that the conventions based
>>>>> approach (i.e., #1) is available today and being followed in
>>>>> OpenConfig defined models.
>>>>>
>>>>> We would like to hear opinions on this from the WG before
>>>>> declaring one of the following as the WG direction:
>>>>>
>>>>>      A) models that wish to support applied configuration MUST
>>>>>         follow conventions based on [1] -- and the WG needs to
>>>>>         formalize these conventions.
>>>>> or
>>>>>      B) no explicit support is required for models to support
>>>>>         applied configuration -- and that the WG needs to
>>>>>         formalize an opstate solution based on the approach
>>>>>         discussed in [4] and [5].
>>>>>
>>>>> We intend to close on this choice before Berlin.
>>>>>
>>>>> Thank you,
>>>>> Lou (and co-chairs)
>>>>>
>>>>> [1] https://tools.ietf.org/html/draft-openconfig-netmod-opstate-01
>>>>> [2] https://tools.ietf.org/html/draft-kwatsen-netmod-opstate-02
>>>>> [3] https://tools.ietf.org/html/draft-wilton-netmod-opstate-yang-02
>>>>> [4]
>>>>> https://tools.ietf.org/html/draft-schoenw-netmod-revised-datastores-00
>>>>> [5]
>>>>> https://tools.ietf.org/html/draft-wilton-netmod-refined-datastores-00
>>>>> * - Chris H. and Acee L.
>>>>>
>>>>>
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>>>>>
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