Re: [netmod] Query about draft-ietf-netconf-rfc7895bis-06

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Wed, 09 May 2018 16:47 UTC

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Date: Wed, 9 May 2018 18:47:35 +0200
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Robert Wilton <rwilton@cisco.com>
Cc: Rohit R Ranade <rohitrranade@huawei.com>, "netmod@ietf.org" <netmod@ietf.org>
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Subject: Re: [netmod] Query about draft-ietf-netconf-rfc7895bis-06
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On Wed, May 09, 2018 at 05:15:12PM +0100, Robert Wilton wrote:
> +1 for a generic solution.
> 
> At the moment RFC 8040 states that ETAGS only apply to configuration, so
> they don't necessarily help with operational data.
> 
> Perhaps we should be introducing something like ETAG support for operational
> as well.  Although, we would need to careful consider the implementation
> performance impact.  Given that operational data may come from multiple
> daemons, it may be very hard to efficiently generate reliable ETAGs that
> span across large chunks of operational data.

Yes, there is fast changing data and slow changing data, there is
expensive data (in terms of instrumentation) and there is inexpensive
data. I think the solution is to let the server decide an which data
to provide etags (or something equivalent). HTTP also has all the
Cache-Control magic - I have no clue whether RESTCONF implementations
and in particular RESTCONF clients do honor HTTP caching mechanisms
and maintain local caches at the HTTP interaction level. It seems HTTP
has a lot to offer here (no surprise) and it is not clear what needs
backporting to NETCONF or whether we are better off making RESTCONF do
all the things NETCONF does - or we do both and the implementations
will ultimately decide. In the long run, maintaining two protocols
providing similar functionality does not seem to be effective.

/js

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