Re: [yang-doctors] when statement of an optional leaf? Does it make an optional leaf?

[Benoit Claise <[e-mail]>]

Thanks Martin for the clarification.

Regards, B.
> Hi,
>
> Benoit Claise <bclaise=[e-mail]> wrote:
>> Hi Lada,
>>
>> Thanks for the XPath correction.
>> When I apply this change, I still see the maintenance-contact as
>> mandatory.
> maintenance-contact has a "mandatory true" statement.  The "when"
> statement doesn't change that.  Hence it is marked as mandatory in the
> tree diagram.  "when" statements are not visible in tree diagrams.
>
>
> /martin
>
>
>> $ pyang -f tree ietf-service-assurance.yang
>> module: ietf-service-assurance
>>    +--ro assurance-graph-version?       yang:counter32
>>    +--ro assurance-graph-last-change?   yang:date-and-time
>>    +--rw subservices
>>       +--rw subservice* [type id]
>>          +--rw type                                identityref
>>          +--rw id                                  string
>>          +--ro last-change? yang:date-and-time
>>          +--ro label?                              string
>>          +--rw under-maintenance?                  boolean
>>          +--rw maintenance-contact                 string
>>
>> I guess the validation is not clever enough to combine "mandatory
>> true" and Xpath (when "../under-maintenance='true'") from
>> maintenance-contact with the optional under-maintenance leaf ... to
>> conclude that maintenance-contact is actually optional.
>>
>> Regards, Benoit
>>> Hi Benoit,
>>>
>>> "maintenance-contact" may remain mandatory - due to its default value,
>>> "under-maintenace" is always present, as far as XPath evaluation is
>>> concerned.
>>>
>>> But because of this, your when expression probably doesn't have the
>>> effect that you expect: it will always be true. I think it needs to be
>>> changed to
>>>
>>>       when "../under-maintenance = 'true'";
>>>
>>> Lada
>>>
>>> Benoit Claise <bclaise=[e-mail]> writes:
>>>
>>>> YANG doctors,
>>>>
>>>> $ pyang -f tree  ietf-service-assurance.yang
>>>> module: ietf-service-assurance
>>>>      +--ro assurance-graph-version?       yang:counter32
>>>>      +--ro assurance-graph-last-change?   yang:date-and-time
>>>>      +--rw subservices
>>>>         +--rw subservice* [type id]
>>>>            +--rw type                                identityref
>>>>            +--rw id                                  string
>>>>            +--ro last-change?                        yang:date-and-time
>>>>            +--ro label?                              string
>>>>            +--rw under-maintenance?                  boolean
>>>>            +--rw maintenance-contact string
>>>>    <===============================
>>>>            +--rw (parameter)?
>>>>            |  +--:(service-instance-parameter)
>>>>            |     +--rw service-instance-parameter
>>>>            |        +--rw service?         string
>>>>            |        +--rw instance-name?   string
>>>>            +--ro health-score?                       uint8
>>>>            +--rw symptoms
>>>>            |  +--ro symptom* [start-date-time id]
>>>>            |     +--ro id                     string
>>>>            |     +--ro health-score-weight?   uint8
>>>>            |     +--ro label?                 string
>>>>            |     +--ro start-date-time        yang:date-and-time
>>>>            |     +--ro stop-date-time?        yang:date-and-time
>>>>            +--rw dependencies
>>>>               +--rw dependency* [type id]
>>>>                  +--rw type               -> /subservices/subservice/type
>>>>                  +--rw id                 ->
>>>> /subservices/subservice[type=current()/../type]/id
>>>>                  +--rw dependency-type?   identityref
>>>>
>>>> The YANG modules comes from
>>>> https://datatracker.ietf.org/doc/draft-claise-opsawg-service-assurance-yang/
>>>> Have a look at
>>>> https://raw.githubusercontent.com/YangModels/yang/ecb622b214e59c5f6312e915d4d65823a6485852/experimental/ietf-extracted-YANG-modules/[e-mail]
>>>>
>>>> The leafs in question:
>>>>
>>>>              leaf under-maintenance {
>>>>                type boolean;
>>>>                default false;
>>>>                description
>>>>                  "An optional flag indicating whether this particular
>>>>                  subservice is under
>>>>                  maintenance. Under this circumstance, the subservice
>>>>                  symptoms and the
>>>>                  symptoms of its dependencies in the assurance graph should
>>>>                  not be taken
>>>>                  into account. Instead, the subservice should send a 'Under
>>>>                  Maintenance'
>>>>                  single symptom.
>>>>
>>>>                  The operator changing the under-maintenance value must set
>>>>                  the
>>>>                  maintenance-contact variable.
>>>>
>>>>                  When the subservice is not under maintenance any longer, the
>>>>                  under-maintenance flag must return to its default value and
>>>>                  the under-maintenance-owner variable deleted.";
>>>>              }
>>>>              leaf maintenance-contact {
>>>>       when "../under-maintenance";
>>>>                type string;
>>>>                mandatory true;
>>>>                description
>>>>                  "A string used to model an administratively assigned name of
>>>>                  the
>>>>                  resource that changed the under-maintenance value to 'true.
>>>>
>>>>                  It is suggested that this name contain one or more of the
>>>>                  following:
>>>>                  IP address, management station name, network manager's name,
>>>>                  location,
>>>>                  or phone number. In some cases the agent itself will be the
>>>>                  owner of
>>>>                  an entry. In these cases, this string shall be set to a
>>>>                  string
>>>>                  starting with 'monitor'.";
>>>>              }
>>>>
>>>> In case of a leaf (maintenance-contact) with a when statement pointing
>>>> to an optional leaf (under-maintenance), should the leaf
>>>> (maintenance-contact) be marked as optional in the tree output?
>>>>
>>>> Regards, Benoit
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