Hi Alex,
On 31/10/2017 17:36, Alexander Clemm wrote:
Hi Rob,
A few comments, inline
--- Alex
*From:*netmod [mailto:[email protected]] *On Behalf Of *Robert
Wilton
*Sent:* Tuesday, October 31, 2017 7:14 AM
*To:* Martin Bjorklund <[email protected]>; [email protected];
[email protected]; Randy Presuhn <[email protected]>
*Subject:* Re: [netmod] Action and RPC statements
Hi,
Here is another attempt for proposed text for Actions/RPC statements
in NMDA.
<new>
6.2 Invocation of RPC Operations
This section updates section 7.14 of RFC 7950.
RPCs MAY be defined as affecting the contents of a specific datastore,
any configuration datastore (e.g., <edit-config>), or any datastore
(e.g., <get-data>). The RPC definition specifies how the RPC input
data is interpreted by the server.
<ALEX> why “e.g., <get-data>”? Does <get-data> affect the contents of
the datastore – I thought it just gets data, hence this example is not
ideal.
There is also no mention about the source of the “in” parameters. It
probably makes sense to mention that explicitly.
Perhaps something along the lines of “RPCs MAY be defined as
_/relating/_ to the contents of a specific datastore…. Input data
resolves to <operational>, as does output data, as do RPC side
effects“. Then below
“RPCs definitions that do not explicitly state an affected
datastore(s) _/refer_to/_ the general operational state of the server.”
Yes, that makes sense.
One other comment, it would be good to also indicate that when an RPC
leads to modification of data nodes, what the “origin” of those
modifications is.
That is an interesting question.
To describe this as a concrete example, if you have a single config true
YANG list for dynamic/configuration subscriptions then a subscription
can be created either via configuration or as an RPC operation.
I would probably classify this as "learned", and I think that we could
extend the definition of the "learned" origin to cover this case.
Thanks,
Rob
</ALEX>
RPCs definitions that do not explicitly state an affected
datastore(s) modify the general operational state of the server.
Hence, if any RPC input data relates to data node instances then
those would generally resolve to data node instances in the
<operational> data tree.
6.3 Invocation of Actions
This section updates section 7.15 of RFC 7950.
In YANG data models, the "action" statement may appear under "config
true" and "config false" schema nodes. While instances of both
schema nodes may appear in <operational>, instances of "config true"
schema nodes may also appear in other datastores.
Actions are always invoked on a data node instance that exist in the
<operational> data tree. The behavior defined by an action statement
is generally expected to affect the operational state of the server
rather than directly modifying the contents of any configuration
datastore.
</new>
On a related note, I also want to confirm that it is right that RPC
input data is always checked against operational:
Section 6.1. of the NMDA draft states:
o If the XPath expression is defined in a substatement to an "input"
statement in an "rpc" or "action" statement, the accessible tree
is the RPC or action operation instance and all operational state
in the server. The root node has top-level data nodes in all
modules as children. Additionally, for an RPC, the root node also
has the node representing the RPC operation being defined as a
child. The node representing the operation being defined has the
operation's input parameters as children.
Is <operational> always the right datastore to evaluate RPC
input/output data relative to? For most RPCs this seems to be the
right choice by default but it also seems plausible that someone may
wish to define an RPC that wants to validate its input parameters
against the contents of another datastore.
An example could be an "is-applied" RPC that takes a path to a subtree
in <running> or <intended> and checks whether the configuration for
that subtree is fully represented in <operational>.
Thanks,
Rob
On 27/10/2017 09:33, Martin Bjorklund wrote:
Andy Bierman<[email protected]> <mailto:[email protected]> wrote:
On Thu, Oct 26, 2017 at 11:22 AM, Randy Presuhn <
[email protected]
<mailto:[email protected]>> wrote:
Hi -
On 10/26/2017 10:44 AM, Robert Wilton wrote:
Hi ,
Separating out the issue regarding which datastore action and
RPC apply
to, we propose the following NEW text to the datastores draft:
6.2 Invocation of Actions and RPC Operations
This section updates section 7.15. of RFC 7950.
In YANG data models, the "action" statement may appear under
"config
true" and "config false" schema nodes. While instances of
both
schema nodes may appear in <operational>, instances of "config
true"
schema nodes may also appear in other datastores.
An NMDA compliant server MUST execute all actions in the
context of
<operational>. Likewise, an NMDA compliant server MUST
invoke all RPC
operations in the context of <operational>, unless the RPC
is
explicitly
defined as affecting other datastores (e.g., <edit-config>).
OK?
A question - I understand the motivation for the "unless" for RPC
operations, but wonder why there is no similar "unless" for actions.
The <rpc> is not really in a datastore at all.
It may have input and output parameters with leafref and must/when
statements.
These are evaluated in the <operational> context.
The <rpc> may in fact be something like <edit-config>
which has parameters (like <config> to apply to
a specific datastore.
The action node is embedded within some data that has to be parsed
in a specific datastore before the action is processed.
This data is required to be in <operational>.
It also has XPath and leafref that needs to be resolved (same as <rpc>).
The side effects of the <rpc> or <action> can impact other datastores.
This would be defined in the description-stmt and this is not a problem.
This is exactly right. We need to capture this in the text.
/martin
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