Re: [netmod] WG LC draft-ietf-netmod-module-tags-02 - 10/2/18 - 10/16/18

[Juergen Schoenwaelder <[e-mail]>]

On Tue, Oct 16, 2018 at 08:31:43AM -0400, Christian Hopps wrote:
> 
> On Oct 2, 2018, at 4:30 PM, Juergen Schoenwaelder <[e-mail]> wrote:

> > - Standard tags defined in description statements
> > 
> >  I do not like this. YANG has extension statements and having to
> >  parse stuff out of free text description statements seems to be a
> >  movement backwards.
> 
> This is used by the human implementer of the module (i.e., they need to write code to implement the module). As such it was not intended for machine parsing.
>

I am personally not convinced. The whole reason why we have YANG is
automation and I believe people will go and write tools to extract
tags and having to extract them out of free form text looks like a
step backwards.

> > - System management
> > 
> >  What is 'system management' and a 'system management protocol'?
> 
> These were derived from the work the RtgYangDT originally did where we were organizing everything under a single device tree. This tree concept was (rightly) abandoned to be replaced with use of tags. Examples of protocols would be Syslog, TACAC+, SNMP, Netconf, ... I've added that to the description.
>

I am generally not a fan of definition by example. Is SSH a 'system
management protocol'?

> > - Tag format
> > 
> >  Apparently, the colon has a special meaning in a tag string and
> >  otherwise there do not seem to be any restrictions. (Which is good,
> >  I can finally put various smileys on my gear.)
> > 
> >  Should we state explicitly somewhere that a colon has a special
> >  meaning and that tag strings are structured into a sequence of
> >  'taggies' separated by colons? Or is definition by example good
> >  enough?
> 
> I think it's good enough. :)

I am not convinced this will work well. My understanding is that other
'hashtags' also have restrictions - whitespace and punctuation
characters are often excluded, it seems. Apparently ':' already means
something special here. Should you later need more special meanings,
you will love to have characters available that you can use. What
about tags that include whitespace or control characters? Do we really
want such tags?

> > - Meaning of tag masks
> > 
> >  Do masks mean a complete string match or can I mask along the prefix
> >  hierarchy, i.e., 'vendor:acme:' masks everything starting with
> >  'vendor:acme:'?
> 
> Exact match, I've added text to clarify this.

OK. One obvious extension is then to have at some point in time tag
match expressions, such as 'vendor:acme:*' (assuming that * is not
a valid character for a tag, see above).

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
Fax:   [phone]         <https://www.jacobs-university.de/>