> On 19 Oct 2015, at 21:04, Juergen Schoenwaelder 
> <[email protected]> wrote:
> 
> On Sun, Oct 18, 2015 at 08:22:25AM -0700, Andy Bierman wrote:
>> 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.
>> 
> 
> To me, auto-deletion feels fragile.

+1

Lada

> 
> /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/>

--
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C




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