Re: [coman] constrained management: best practice for "features"

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Sun, 26 October 2014 19:40 UTC

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Date: Sun, 26 Oct 2014 20:40:09 +0100
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Thomas Watteyne <watteyne@eecs.berkeley.edu>
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Subject: Re: [coman] constrained management: best practice for "features"
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On Sun, Oct 26, 2014 at 12:07:33PM -0700, Thomas Watteyne wrote:
> *[sending to both 6TiSCH and COMAN MLs]*
> 
> While discussion management of 6TiSCH devices, Jonathan brought up an
> important question [1] while reviewing draft-ietf-6tisch-6top-interface [2]:
> 
> * Are all things in the YANG model required?  For example, must one support
> > reading the READ.timesource for minTimeCorrection?
> >
> 
> I'd like to poll the lists for best practice in (constrained) management
> and optional portions of data model:
> 
>    1. are "features" [3] the correct mechanism for marking portions on a
>    data model optional?

Yes

>    2. how widely used are features; are they considered good practice?

$ grep -h -i feature.*\{ ietf-*yang | sort -u  | wc -l
      38

They are apparently not considered bad practice. However, making
single leafs features may be considered bad style. Usually features
are used to mark logical sub-components that may not be always
implemented as optional.

>    3. is GETing the resource /restconf/<module_name>/feature in RESTconf
>    the default way for discovering features?

I think the data model in draft-ietf-netconf-restconf-03.txt section 9
is a bit more complex (you seem to be looking at an old
specification).

>    4. would a HTTP/CoAP status code (e.g. "501 Not Implemented") be a
>    viable alternative for feature discovery?

Unclear. Which request would trigger this?

>    5. In general, what are the opinions from the 6TiSCH WG about using
>    features?

Can't answer this one.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1, 28759 Bremen, Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>