Re: [netmod] Confirming draft-ietf-netmod-module-tags-03 consensus call

[Robert Wilton <[e-mail]>]

Hi Chris,

On 13/11/2018 21:05, Christian Hopps wrote:
> The servers implement the modules which can have predefined tags from the module designer as well as the implementer (vendor) which literally cannot come from anywhere *but* the server that implements the module.

Clients should also be able to know find out the predefined tags from 
the module definition.  I agree that the any tags added by the 
implementation can only be known by querying the server, although its 
not obvious to me what those tags would be.  E.g. if Cisco had a YANG 
module for EIGRP and wanted to give it the ietf:protocol and 
ietf:routing tag then it would ideally use the extension and put it in 
the YANG file.

> This is not what I thought would hold this work up.

Sorry, I'm not trying to hold anything up.

It not obvious to me how the ietf-module-tags modules will actually be 
used on a device:
  1) being able to ask a device: "What are all the YANG modules that are 
implemented on this device that are routing protocols" seems a useful 
thing to do.  Although personally I would ideally want the answer in the 
context of YANG library.  I.e. to see the modules with the given tags, 
along with module evision/version, features and any deviations.  This 
can probably be achieved today with an appropriate xpath query, if 
supported, or could perhaps be achieved more easily if the operational 
list of tags also augmented the module entries in the YANG library 
structure.  But perhaps for your envisaged use case just getting back 
the list of modules with that tag is sufficient and is what you are after.

Is this how you are envisaging YANG module tags would be used, and if 
so, would it do any harm to add a short section near the intro 
explaining this (and perhaps the YANG catalogue example as well)?  Or do 
you think that this would just be needless noise.

2) Being able to filter queried data based on tags may also be useful, 
but this would require protocol extensions, perhaps something to be done 
in future?

Thanks,
Rob


>
> Thanks,
> Chris.
>
>> On Nov 13, 2018, at 5:58 AM, Robert Wilton <[e-mail]> wrote:
>>
>> Hi Joel, authors,
>>
>> I have to confess that I didn't have time to review this during the last call (but have reviewed/provided comments on previous versions).
>>
>> These comments may be too late, but I will provide them anyway, so make of them what you will :-)
>>
>> In summary, I like the idea of tags and I think that they are a good fit for classifying YANG models.  In particular, I think that a flexible classification of YANG modules is better than a rigid structure that can never be changed.
>>
>> For me the one of the great utilities of module tags could be in applications like YANG catalog search (https://yangcatalog.org/yang-search/).  Being able to search for modules by tag seems like it would be a particularly useful thing to be able to do.
>>
>> However, I do have some sympathy with Alex's comment, in that it is a bit unclear as to benefits of configuring the tag information on the devices.  At the moment, the configuration doesn't have any material affect on the device, and the only thing that a client can do is read back the tag configuration.  Is the intention that the protocols may be extended in future to allow filter queries to be based on module tags?
>>
>> So, I am supportive of Alex's comment that it would give the document more clarity if some of the specific use cases could be described.
>>
>>
>> Some other random comments/nits:
>>
>> 1) 6087bis references can be updated to RFC 8407.  Is a reference even allowed in the abstract?
>>
>> 2) Abstract: "writing a modules tags" => "writing a module's tags" or "writing module tags"
>>
>> 3) The module is YANG 1.1, so RFC 6020 reference can be changed to RFC 7950.
>>
>> 4) Section 3.4: Should there be a tag prefix for "experimental"? Or perhaps this would be "ietf:experimental:<tag-name>" anyway.
>>
>> 5) Section 5.1: It might be useful if the tags were also reported under YANG library, e.g. as an augmentation to rfc7895bis.  E.g. this would report the same information as "modules-tags/module[name]/tag" leaf-list.
>>
>> 6) YANG module: Should you limit the maximum size of a tag? Perhaps to 255, or 1000 characters.
>>
>> 7) Line length for "The operational view of this list is constructed ..." looks like it may be too long.
>>
>> 8) Section 7, Guidelines to authors.  I was wondering if this section should state that YANG modules SHOULD define standard tags that are associated with it.  At the moment, it just states what can be done, without providing guidance of what should be done.
>>
>> 9) Section 9.2.  A few more possible categories: discovery protocol, vpn, tunnel.  I'm not sure that I particularly like "rfc8199-" as a module name, and possibly "classification-" would be better.
>>
>> Apologies for the tardy review comments,
>> Rob
>>
>>
>> On 12/11/2018 16:46, joel jaeggli wrote:
>>> During the Thursday nov 8 session of netmod, we asked if there were any objections to the publication of the Draft-03 version of draft-ietf-netmod-module-tags which addresses comments and concerns raised during the WGLC. In the meeting there were none. This commences a comment period to confirm that call. As this follows closely on the heels of the IETF 103 meeting we’ll let the call run through Monday the 26th of November.
>>>
>>> https://tools.ietf.org/rfcdiff?url2=draft-ietf-netmod-module-tags-03.txt
>>>
>>>
>>> Thanks
>>> Joel
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