Re: [yang-doctors] question regarding conditional/optional statements

[Martin Bjorklund <[e-mail]>]

Jan Lindblad <[e-mail]> wrote:
> Option 5: Let each implementation return the data it supports without
> any content declaration
> 
> Since this is optional operational data, it's formally up to the
> application to simply return any collected data it has and skip any
> other leafs.

I was just going to suggest this as well.  I think the description
statement can make it clear that if the implementation doesn't have a
value for the counter, the node is not instantiated.  (note that this
is slightly different from saying that the node is not implemented;
the instrumentation code would know the names of all counters, but
not instantiate all of them, rather than just know the names of the
ones it "supports".)


/martin


> Advantage: Dead simple to understand for server and client alike, and
> zero complication on the YANG level. IMO cleaner and clearer than
> options 2, 3, 4. Even if any of the options 2-4 were implemented, the
> client would still have to be prepared to not receive any particular
> leaf since they are all optional. If I implemented the client, I
> probably wouldn't even bother to read that bit mask/whatever.
> 
> Disadvantage: Application developers will have no way of knowing a
> priori which data may arrive from a particular server. If this is
> important, option 1 would clearly be better.