Re: [netmod] choice/case in tree diagrams

Mahesh Jethanandani <mjethanandani@gmail.com> wrote:
> 
> 
> > On Mar 5, 2018, at 6:27 AM, Martin Bjorklund <mbj@tail-f.com> wrote:
> > 
> > Martin Bjorklund <mbj@tail-f.com <mailto:mbj@tail-f.com>> wrote:
> >> Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> wrote:
> >>> On Mon, Mar 05, 2018 at 02:54:18PM +0100, Martin Bjorklund wrote:
> >>>>> 
> >>>>> So it seems the running code got it right. ;-)
> >>>> 
> >>>> As the author of that code, I think that was purely by accident...
> >>>> 
> >>>> But I'm not convinced it is the correct solution.  We have one example
> >>>> in the other thread where someone was confused by the "rw" flag and
> >>>> thought that it implied that the node would be present in the data
> >>>> tree.
> >>>> 
> >>> 
> >>> So what does rw mean?
> >>> 
> >>> (i)  The schema node has a rw property.
> >>> (ii) The schema node can be instantiated and the instantiated data
> >>> node
> >>>     has a rw property.
> >>> 
> >>> I think it is difficult to have both at the same time. If the tree is
> >>> a representation of schema nodes, then (i) seems to make more
> >>> sense. That said, the explanation in 2.6 is somewhat vague since it
> >>> says 'data' and not 'nodes' (like everywhere else):
> >>> 
> >>> OLD:
> >>> 
> >>>       <flags> is one of:
> >>>         rw  for configuration data
> >>>         ro  for non-configuration data, output parameters to rpcs
> >>>             and actions, and notification parameters
> >>> 
> >>> NEW:
> >>> 
> >>>       <flags> is one of:
> >>>         rw  for configuration data nodes
> >>>         ro  for non-configuration data nodes, output parameters to rpcs
> >>>             and actions, and notification parameters
> >> 
> >> I think this is ok.  But that means that we also have to add:
> >> 
> >>           --  for a choice or case node
> >> 
> >> But in order to be consistent, we should probably have:
> >> 
> >>           --  for a choice, case, input or output node
> > 
> > Whoops, it shouldn't be "--".  Somehow we should say that no flags are
> > used for choice,case,input,output.
> 
> I would agree, as having choice/case statements represented as schema
> nodes is not only confusing in the tree diagram

Well, choice and case *are* schema nodes.  They are printed within
parentheses, which may give you a hint that they are not data nodes
and thus not visible in the payload.

The tree diagram is intended as a compact, easy-to-read representation
of the structure of the YANG module.  They will not contain all
details needed to produce good examples.

/martin

, but also confusing
> when constructing an example. The tree diagram represents it as a
> node, where one would put it in the example, but validation complained
> about it (not being a node).
> 
> > 
> > 
> > /martin
> > 
> > 
> >> 
> >> 
> >> This means that the correct tree syntax for choice and case will be:
> >> 
> >>     +-- (subnet)?
> >>        +-- :(prefix-length)
> >>        |  +--rw prefix-length?   uint8
> >>        +-- :(netmask)
> >>           +--rw netmask?         yang:dotted-quad
> >> 
> >> 
> >> /martin
> >> 
> >> 
> >>> The document (as far as I searched for it) does not clearly say that
> >>> 'node' means 'schema node'. In hindsight, it might have been useful to
> >>> explicitely import terminology from RFC 7950 and to use it carefully
> >>> (RFC 7950 has 'schema node' and 'data node' but here we largely talk
> >>> about 'nodes' - and my assumption is that this means 'schema nodes'.)
> >> 
> >> _______________________________________________
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> >> netmod@ietf.org
> >> https://www.ietf.org/mailman/listinfo/netmod
> >> 
> > 
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> Mahesh Jethanandani
> mjethanandani@gmail.com
> 