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

[Martin Björklund <[e-mail]>]

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
> >> _______________________________________________
> >> yang-doctors mailing list
> >> [e-mail]
> >> https://www.ietf.org/mailman/listinfo/yang-doctors
> 
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