Hi Martin, Andy,
Despite what YANG the language allows, I think that it is much cleaner
use of the language to split types/groupings that are expected to be
shared by other modules into separate "*_types.yang" modules.
I agree with Andy that it is strange to support a feature in a module
that is not itself implemented.
My hope with YANG library-bis is that most implementations can get by
with an empty "import-only-modules" list, and that they can define all
modules (including types only modules) in the "module" list of
implemented modules.
So, I actually think that the workaround using deviations below is OK,
because this scenario should be avoidable by having a clean separation
between external reusable types and implementable nodes.
Thanks,
Rob
On 31/01/2019 08:44, Martin Bjorklund wrote:
Andy Bierman <a...@yumaworks.com> wrote:
Hi,
I do not agree these changes should be made at this late date.
It seems to me that in order to support a feature you have to implement it,
and therefore if any features are set then the module is implemented, not
imported.
But this is not what RFC 7950 says about implement:
A server implements a module if it implements the module's data
nodes, RPCs, actions, notifications, and deviations.
All features should be set to false in an import-only module.
IMO this interpretation holds for typedef modules like iana-crypt-hash.
We list that as implemented (because it is) and the features that are
supported are set.
If a module consists only of typedefs, there is no problem.
Conformance "import" or "import-only" modules exist in YL b/c modules
may have a mix of typedefs and data nodes etc.
So in the case that Lada brought up, a server would have to list the
module as implemented with a certain set of features; and then also
deviate all nodes/rpc/notifc etc as 'not-implemented'.
/martin
Andy
On Wed, Jan 30, 2019 at 11:03 AM Martin Bjorklund <m...@tail-f.com> wrote:
Hi,
Ladislav Lhotka <lho...@nic.cz> wrote:
Hi,
unlike RFC 7895, 7895bis doesn't provide the "feature" leaf list for
import-only modules. But is it really so that features have no use in
such modules?
For example, an enum can depend on a feature, and if it is inside a
typedef, it can also be in an import-only module. What if that feature
is defined in the same module?
I think you're right, and that this is an unfortunate omission.
The fix is simple though; we would have to add the leaf-list features
to import-only. Probably refactor the "feature" leaf-list into a
grouping so it works like the grouping location-leaf-list:
grouping feature-leaf-list {
leaf-list feature {
type yang:yang-identifier;
description
"List of all YANG feature names from this module that are
supported by the server, regardless whether they are defined
in the module or any included submodule.";
}
}
And then "uses feature-leaf-list":
OLD:
grouping module-implementation-parameters {
description
"Parameters for describing the implementation of a module.";
leaf-list feature {
type yang:yang-identifier;
description
"List of all YANG feature names from this module that are
supported by the server, regardless whether they are defined
in the module or any included submodule.";
}
NEW:
grouping module-implementation-parameters {
description
"Parameters for describing the implementation of a module.";
uses feature-leaf-list;
And in the list "import-only":
OLD:
uses location-leaf-list;
uses feature-leaf-list;
/martin
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