Hi Joey,
Your proposal looks fine to me, since it doesn't change the semantics of the
data model. Note that https://tools.ietf.org/html/rfc7950#section-11 says:
o Any set of data definition nodes may be replaced with another set
of syntactically and semantically equivalent nodes. For example,
a set of leafs may be replaced by a "uses" statement of a grouping
with the same leafs.
Kent
--
Hello,
Does anyone have thoughts on this?
Regards,
Joey
-----Original Message-----
From: JOEY BOYD
Sent: Wednesday, September 27, 2017 9:06 AM
To: 'netmod@ietf.org'
Subject: Backward Compatibility Question
Hi all,
Suppose I had a published YANG model with the following leaf.
leaf thing1 {
type uint8;
description
"Thing 1.";
}
Later, I realize that I wish I had modeled this in a choice as I now have a
mutually exclusive option to 'thing1' which I want to add to the model.
leaf thing2 {
type empty;
description
"Thing 2.";
}
This is a very simplified example but should be sufficient to demonstrate the
problem.
If I look at the XML representation of 'thing1', it looks like this.
<thing1>123</thing1>
If I were to move 'thing1' into a choice with a single case, it would look like
this.
choice things {
case thing1 {
leaf thing1 {
type uint8;
description
"Thing 1.";
}
}
}
Looking to the XML representation, it looks the same as before.
<thing1>123</thing1>
To me, this means that taking a single node or set of nodes and moving them
under a case within a new choice statement is a backward compatible change.
This assumes, of course, any mandatory or default behavior is preserved. I now
can add 'thing2' to the existing model as an option to 'thing1'.
choice things {
case thing1 {
leaf thing1 {
type uint8;
description
"Thing 1.";
}
}
case thing2 {
leaf thing2 {
type empty;
description
"Thing 2.";
}
}
}
Do you agree with this analysis or am I missing something?
Best regards,
Joey
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