Re: [netmod] Please clarify implementation about ‘when’

[Andy Bierman <[e-mail]>]

On Mon, Sep 9, 2019 at 7:10 PM Fengchong (frank) <[e-mail]>
wrote:

> Hi andy,
>
>
>
> You only talk about the constraints on rpc operation’s parameter?
>
>
>
> Do you have any opinion about my question?
>

8.3.1 does not apply to leaf 'b'.
The RPC parameter is called 'config'.
It has no when-stmts to evaluate.
Rob is correct.
His example shows what 8.3.1 would cover.

Andy



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> *发件人:* Andy Bierman [mailto:[e-mail]]
> *发送时间:* 2019年9月10日 1:14
> *收件人:* Rob Wilton (rwilton) <[e-mail]>
> *抄送:* Fengchong (frank) <[e-mail]>; [e-mail];
> Yangang <[e-mail]>
> *主题:* Re: [netmod] Please clarify implementation about ‘when’
>
>
>
> Hi,
>
>
>
> None of the operations that accept or return datastore contents expose the
> datastore objects
>
> in the RPC parameters.  They are always anyxml or anydata. This means that
>
> there are no descendant data nodes defined at all according to the RPC
> operation
>
> and therefore the constraints on those nodes do not exist in the RPC
> operation either.
>
>
>
>
>
>
>
> On Mon, Sep 9, 2019 at 6:41 AM Rob Wilton (rwilton) <[e-mail]>
> wrote:
>
> Hi Frank,
>
>
>
> My interpretation of what the expected behaviour is as follows.
>
>
>
> For “scene 1”, the config change is accepted because the result of the
> config datastore after the edit-config has been applied is valid.
>
>
>
> For “scene 2”, the config change is rejected because the result of the
> config datastore after the edit-config has been applied is invalid.
>
>
>
> My interpretation is that the block of text in 8.3.1 payload parsing is
> primary intended to refer to RFC input.  E.g. if the RPC was defined
> something like below, then the ‘when’ rule in 8.3.1 would enforce that a
> zip-code can only be provided if the country is the USA.
>
>
>
>        rpc rock-the-house {
>
>          input {
>
>            leaf country {
>
>              type string;
>
>            }
>
>            leaf zip-code {
>
>              when “../country = ‘usa’”;
>
>              type string;
>
>            }
>
>          }
>
>        }
>
>
>
> Thanks,
>
> Rob
>
>
>
>
>
>
>
> *From:* netmod <[e-mail]> *On Behalf Of *Fengchong (frank)
> *Sent:* 06 September 2019 08:19
> *To:* [e-mail]
> *Cc:* Yangang <[e-mail]>
> *Subject:* [netmod] Please clarify implementation about ‘when’
>
>
>
> Hi all,
>
>
>
> In RFC7950 secton 8, several description about when：
> In section 8.2 <https://tools.ietf.org/html/rfc7950#section-8.2>.
> Configuration Data Modifications
>
>    o  If a request modifies a configuration data node such that any
>
>       node's "when" expression becomes false, then the node in the data
>
>       tree with the "when" expression is deleted by the server.
> In 8.3.1 <https://tools.ietf.org/html/rfc7950#section-8.3.1>.  Payload
> Parsing
>
>    o  If data for a node tagged with "when" is present and the "when"
>
>       condition evaluates to "false", the server MUST reply with an
>
>       "unknown-element" <error-tag> in the <rpc-error>.
>
> In 8.3.2 <https://tools.ietf.org/html/rfc7950#section-8.3.2>.  NETCONF
> <edit-config> Processing
>
> Modification requests for nodes tagged with "when", and the "when"
>
>       condition evaluates to "false".  In this case, the server MUST
>
>       reply with an "unknown-element" <error-tag> in the <rpc-error>.
>
>
>
> YANG module：
>
> module foo {
>
>    namespace “http://foo.com”;
>
>    prefix “foo”;
>
> Leaf a {…}
>
> Leaf b {
>
>   When “a = 10”;
>
> }
>
> }
> Scene 1:
>
> The first edit-config request:
>
> <edit-config>
>
>    <target>
>
>       <candidate/>
>
>    </target>
>
>    <config>
>
>       <a xmlns= “http://foo.com”>3</a>
>
>    </config>
>
> </edit-config>
>
> This request will set a = 3.
>
>
>
> The second request:
>
> <edit-config>
>
>    <target>
>
>       <candidate/>
>
>    </target>
>
>    <config>
>
>       <a xmlns= “http://foo.com”>10</a>
>
>       <b xmlns= “http://foo.com”>5</b>
>
>    </config>
>
> </edit-config>
>
>
>
> According 8.3.1, in rpc payload parsing phase, the a’s value in candidate
> datastore is 3,so leaf b’s when condition is evaluated to false, server
> will report ‘unknown-element’ error.
>
> Is it expected by user?
> Scene 2:
>
> The first edit-config request:
>
> <edit-config>
>
>    <target>
>
>       <candidate/>
>
>    </target>
>
>    <config>
>
>       <a xmlns= “http://foo.com”>10</a>
>
>    </config>
>
> </edit-config>
>
> This request will set a = 10.
>
>
>
> The second request:
>
> <edit-config>
>
>    <target>
>
>       <candidate/>
>
>    </target>
>
>    <config>
>
>       <a xmlns= “http://foo.com”>3</a>
>
>       <b xmlns= “http://foo.com”>5</b>
>
>    </config>
>
> </edit-config>
>
> According 8.3.1, in rpc payload parsing phase, the a’s value in candidate
> datastore is 10, so leaf b’s when condition is evaluated to true, server
> will accept this request in payload parsing phase.
>
>
>
> In edit-config request processing phase, if leaf a’s modification is
> processed firstly, the a’s value will be changed to 3, so the b’s when
> condition will be false, when server process b’s modification, b will be
> treated as unknown-element, the edit-config request will fail.
>
> If leaf b’s modification is processed firstly, server will accept this
> modification ,because b’s when condition is true, and when server process
> a’s modification , this modification will be accepted, and b’s when
> condition will be evaluated to false, leaf b will be deleted automatically,
> the edit-config request will be OK.
>
>
>
> How server should process this situation?
>
>
>
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