Re: Returning zero or empty string for unsupported objects

["Randy Presuhn" <randy_presuhn@mindspring.com>]

Hi -

> From: "C. M. Heard" <heard@pobox.com>
> To: "Mreview (E-mail)" <mreview@ops.ietf.org>
> Sent: Thursday, November 06, 2003 5:54 PM
> Subject: Re: Returning zero or empty string for unsupported objects
>

> Greetings,
>
> I think Dave's analysis is right on ... it is not necessarily wrong
> for an object definition to specify that a special value be returned
> to indicate that a function isn't supported.  If we did make such a
> blanket rule I think we'd be guilty of creating an unnecessary rule.
> I say let this remain a design choice.  (Of course, it's always
> fair for a reviewer to ask a designer to consider alternatives ... I
> just don't think this one should be elevated to the status of a
> SHOULD or MUST.)
...

I think the underlying principle is that the agent should not lie.
If the object definition provides a "not supported" value, then
an agent reporting that value isn't lying.  If the object definition
(or underlying data type) does not provide for such a sentinel value,
then instantiating the object will lead management applications to
draw erroneous conclusions.

Randy (who just saw a MIB where the WG wanted interface counters
to count or return constant zero depending on what chip set
was used in the implementation.)