Re: [YANG] default values

On Thu, Jan 17, 2008 at 04:01:50PM +0100, Ladislav Lhotka wrote:

> At the start of a NETCONF session, the values in the
> running/startup/whatever configuration may be different even if the
> server's factory defaults follow the standards. The client can't IMO
> safely avoid checking or setting all variables in server's
> configuration.

Sure. But when I create something new without specifying all defaults,
do I know what I get? In SNMP, you don't. In YANG, you do.

> > 
> > The alternative would be to have a mechanism allowing implementations
> > to post the defaults they are going to use rather than hard wiring
> > defaults in the specification. So a vendor can augment a standard with
> > the defaults that the vendor's implementation is using. This surely
> > adds some complexity. An even further reaching mechanism would be to
> > make the defaults being used by an implementation itself writable,
> > e.g. by introducing a template mechanism which adds defaults for stuff
> > not defined explicitely by a NETCONF client.
> > 
> > Our goal was to start with something simple, allowing us to add more
> > powerful mechanism via extensions over time once we see that they are
> > really needed (that is there is enough uptake of NETCONF / YANG).
> 
> I think this applies to the default statement, too. I am arguing it's
> not needed for NETCONF operation and may complicate things.

So if I understand right, your proposal is to remove the default
statement, not to change its semantics, correct?

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1, 28759 Bremen, Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>

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