[netmod] instance file format and etags/timestamps, xml attributes

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Wed, 28 November 2018 10:01 UTC

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Date: Wed, 28 Nov 2018 11:01:16 +0100
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
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Subject: [netmod] instance file format and etags/timestamps, xml attributes
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draft-ietf-netmod-yang-instance-file-format-00.txt says:

   The JSON format SHALL follow the format of the reply returmed for a
   RESTCONF GET request directed at the datastore resource:
   {+restconf}/data.  ETags and Timestamps SHOULD NOT be included, but
   if present SHOULD be ignored.

I assume that you mean the JSON content in the message-body of the
HTTP Response message for GET message. My understanding is that ETags
and Timestamps (what are these precisely?) are carried in the HTTP
header. So how could the ETag or 'Timestamps' be in the JSON data?  We
should not mess up the HTTP difference between header data and payload
data.

I also do not fully understand the text concerning the XML format.

   The XML format SHALL follow the format returned for a NETCONF GET
   operation.  The <data> anydata (which is not part of the real data
   itself) SHALL contain all data that would be inside the <data>
   wrapper element of a reply to the <get> operation.  XML attributes
   SHOULD NOT be present, however if a SW receiving a YANG Based
   Instance data file encounters XML attributes unknown to it, it MUST
   ignore them, allowing them to be used later for other purposes.

It is unclear what exactly is the instance data - the entire reponse?
Everything inside <data>? Everything inside and including <data>? I
assume the second sentence is trying to say the later but I do not
find it very clear not does it seem to be right. The examples show to
content of the NETCONF <rpc-reply><data/></rpc-reply> inside a <data>
container that belongs to the instance data format (two times <data>
but in different namespaces).

It is also unclear to me why XML attributes are to be removed. Why is
that? If I snapshot <operational>, why should I remove important
information such origin annotations? And removing attributes is
actually plain wrong if you consider that attributes carry XML
namespaces.

/js

PS: I am also concerned about the revision being not fine grained
    enough to be useful. I would love to have a much more precise
    timestamp telling me when the instance data was recorded. I would
    probably replace 'revision' with simply a 'timestamp' or add next
    to a 'revision' a more fine grained 'timestamp'.

-- 
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/>