Subject: [netmod] default terminology

From: Martin Bjorklund <[email-masked]>
Date: Wed, 26 Aug 2009 21:30:38 +0200 (CEST)

Hi,

I think some of the confusion in the recent discussions comes from
inconsistent terminolgy.

When we say 'server assigned', or 'assigned-by system', it refers to
data that is present in the config, just like normal, client created
data ('assigned-by user' if you will).  Since this data is part of the
data store, it is not hidden, it is not phantom nodes, and it is
reported in a normal get-config, regardless of the value of any
with-defaults parameters.

Then we have 'default data'.  I like to view this as the value that is
operationally used if the node is not present in the data store.  YANG
supports one kind of default data only - static defaults, i.e. a
static value, guaranteed to be the same in all implementations,
specified in the data model.  One can imagine dynamic default values,
and I think this is what Andy calls 'hidden' or 'phantom'.

/martin

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From: Phil Shafer <[email-masked]>
Date: Wed, 26 Aug 2009 15:44:59 -0400

Martin Bjorklund writes:
>One can imagine dynamic default values,

I _think_ (but could easily be wrong) that Andy's hangup
was the definition he had in the with-defaults draft,
which said only _client_ supplied data values were
returned with the "explicit" behaviour:

   o  Explicitly set default data: Data that is explicitly set by the
      NETCONF client to its default value.  Some servers MAY treat
      explicitly set default data as simple default data, as they may
      not be able to differentiate between them.

Since configuration data is set from a number of sources (including
snmp, cli users, and "assigned-by system" data), the first paragraph
here needs to be broadened to include data set by any source.
(Default values in a YANG module would not constitute such a source.)

I'm hoping that was the origin of the confusion, and that we can
resolve this issue and move forward.

Thanks,
 Phil

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From: WashamFan <[email-masked]>
Date: Thu, 27 Aug 2009 14:11:40 +0800

Hi,

----- Original Message -----
From: Martin Bjorklund <[email-masked]>
Date: Thursday, August 27, 2009 3:31 am
Subject: [netmod] default terminology
To: [email-masked]

>  and I think this is what Andy calls 'hidden' or 'phantom'.

IMO, dynamic defaults should be treated as 'a-by system' or anything
else and should be presented explicitly in the config. It makes little sense
letting clients to deduce what the exact default is in different cases.

washam