On Sun, Oct 18, 2015 at 7:43 AM, Ladislav Lhotka <[email protected]> wrote:

>
> > On 18 Oct 2015, at 11:52, Juergen Schoenwaelder <
> [email protected]> wrote:
> >
> > On Thu, Oct 15, 2015 at 06:03:57PM +0200, Martin Bjorklund wrote:
> >>
> >> Ok, you're right.  8.2.1 should be kept as it is.  (we may need to
> >> rephrase the intro text in 8.2) But I think Balazs is also right.
> >> Suppose you have:
> >>
> >>  leaf a {
> >>    when "../b = 42";
> >>    type int32;
> >>  }
> >>  leaf b {
> >>    type int32;
> >>  }
> >>
> >> and the db contains b=10.
> >>
> >> Suppose I send an edit-config with a=2.  What is the result?
> >>
> >>  1)  you get an error back
> >>  2)  you get ok; the request to set a to 2 is silently dropped
> >>  3)  something else
> >>
> >
> > Isn't the simplest to always make the changes that were requested in
> > the rpc/action (e.g. edit-config) and then to validate the result and
> > if it fails to validate to return an error? No magic addition or
> > removal of nodes while trying to guess what the client wanted to
> > achieve. I am likely missing details since I never implemented this
>
> That would be the type of behaviour I'd prefer. The auto-deletion feature
> also goes against the principle of least embarrassement - a trivial error
> can inadvertently erase substantial parts of a data tree.
>
>
This goes against the Postel Principle,
You can make your code as fragile as possible if you want.
I have always written servers that try to figure out what the client is
doing.

It seems obvious to me that when-stmt is applied after edits are applied,
just like a choice-stmt.

The server should not be guessing that valid edits from the client
are really programming errors.




> Lada
>

Andy


>
> > but having a processing logic that is simple to understand would be
> > good and I think it is fair to expect that clients send edits that
> > do not require the server to guess what should happen.
> >
> > /js
> >
> > --
> > Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> > Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
> > Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>
> >
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>
> --
> Ladislav Lhotka, CZ.NIC Labs
> PGP Key ID: E74E8C0C
>
>
>
>
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