Re: [Netconf] In an update, when is a delete a delete?

[Alexander Clemm <[e-mail]>]

Hi Andy,
Below
--- Alex

From: Andy Bierman [mailto:[e-mail]]
Sent: Thursday, May 18, 2017 6:34 PM
To: Alexander Clemm <[e-mail]>
Cc: Kent Watsen <[e-mail]>; Eric Voit (evoit) <[e-mail]>; Netconf <[e-mail]>
Subject: Re: [Netconf] In an update, when is a delete a delete?

……………………
<snip>
I interpret the “modified-in” and “modified-out” suggested by Kent precisely as a distinction between those cases.  “Modified-out” simply means its value changed so it no longer matches the filter (but the object still exists).  Whether we call it modified-in/out or something else is another question.  Of course, the issue is that this means this is a new case that is not covered by the patch syntax, which would require an extension of the encoding.



What breaks if the client just sees data nodes appear or disappear from 1 patch to the next?
Why does the client need to know the data node still exists, but the foo==5 filter changed.
The client decided that only state for foo==5 needs to be watched, so from its POV
the extra metadata should not be needed.


<Alex>
For periodic, this is what happens.
In the case of on-change, we would indicate changes.  If a data node is not included in an update, how would we be able to distinguish between the case of (not included because no change) and (not included because no longer meets the filter)?  We do need to indicate to the subscriber that there has been a change in that the data node no longer meets the criteria.  Presumably we want to distinguish this from the case that the data node ceased to exist.  (Not distinguishing those cases would put us back to alternative #1, which I think the consensus is that we don’t want that)
</ALEX>