Re: [netmod] Module tags

[Christian Hopps <[e-mail]>]

Martin Bjorklund <[e-mail]> writes:
> Christian Hopps <[e-mail]> wrote:


> The augmentation of yang-library is not sufficient b/c it is config
> false only.  That's why a separate config list is also needed.

Or an in-module config:true list of tags, but yes, your right.

>
>> Again the in module list allows for single xpath selection of a given
>> node for all modules that have a certain tag set. I found this rather
>> elegant, so that's why I've argued to keep it. I want to make sure that
>> people have considered this before we abandon it.
>
> Just to be clear, the use case is only for the case where several
> different modules implement the exact same structure, right?  Do you
> have any example where this is the case?  Or maybe I didn't understand
> the use case; if so, could you provide a more complete use case?

In another thread I gave the example of IGP hello timers. The xpaths
currently are exactly the same, but without a way (e.g., tagging interfaces)
to make use of the commonality one wouldn't expect the commonality to have
grown organically I don't think. Also, if I'm not mistaken, even the
xpaths don't have to be exactly the same if one uses regular
expressions, just the final node names.

>> I'm OK with removing the add/delete RPCs as they do seem redundant.
>>
>> Is there a way to get the reset to default behavior? We do allow the
>> user to remove default set tags, so I think that's why Lou added that
>> RPC.
>
> I assume that reset to default would be to remove all configured tags
> from the config.  If so that is clearly supported.

It would also put back any default tags that had been removed. In any
case I was just curious if it was possible. The reset RPC would still
have the issues with doing an end-run around the normal config
operations so I'm fine with removing it as well.

>> > Oddly, the draft relies on XPath filtering to retrieve modules with a certain tag.
>> > There is no <find-tags> operation.
>> > That is the 1 RPC operation that might be justified.
>> >
>> > e.g.:
>> >
>> >  rpc find-tags {
>> >   description "find all modules with the specified tag(s).";
>> >   input {
>> >    leaf-list tag { type string; }
>> >   }
>> >   output {
>> >    leaf-list module-name { type string; }
>> >   }
>> >  }
>>
>> This does seem useful, we can add it.
>
> But this is an XPath one-liner:
>
>   /modules-state/modules/name[../module-tag = 'foo']

Yes, xpath is nice that way. :) I figured the RPC was useful in the case
that xpath wasn't supported.

Thanks,
Chris.

> /martin