Hi,
It seems we will not reach full agreement on some of the remaining
issues in 6020bis. Re-opening Y26 is one of them. I don't think this
is a good idea, but I realize that the consensus is to relax the "MUST
NOT augment mandatory nodes" rule.
Here is my proposal for new text. Most of this text is copied from
6087bis, so if we add this to 6020bis, 6087bis should probably be
updated as well.
This new subsection would go into 7.17 The augment Statement.
*** Augmenting Conditionally Mandatory Nodes
If the target node is in another module, then nodes added by the
augmentation MUST NOT be mandatory nodes (see ^terminology^), except
as described below. The reason for this is that clients that do not
know about the augmenting module should contiune to work.
It is possible to add conditional augment statements such that an old
client would not know about the new condition, and would not specify
the new condition. The conditional augment statement can contain
mandatory nodes only if the condition is false unless explicitly
requested by the client.
If the augmentation adds mandatory nodes to a target node in another
module, the augmentation MUST be conditional with a "when" statement.
Care must be taken when defining the "when" expression, so that
clients that do not know about the augmenting module do not break.
**** Usage Example
In the following example, it is OK to augment the "interface" entry
with "mandatory-leaf" because the augmentation depends on support for
"some-new-iftype". The old client does not know about this type so it
would never select this type, and therefore not be adding a mandatory
data node.
module example-augment {
namespace "urn:example:augment";
prefix mymod;
import ietf-interfaces {
prefix if;
}
identity some-new-iftype {
base if:interface-type;
}
augment "/if:interfaces/if:interface" {
when "if:type = 'mymod:some-new-iftype'";
leaf mandatory-leaf {
mandatory true;
type string;
}
}
}
/martin
_______________________________________________
netmod mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/netmod
