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

[Balázs Lengyel]

Hello Jurgen, Thanks for the comments. See answers below. regards Balazs On 2018. 11. 28. 11:01, Juergen Schoenwaelder wrote: 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. BALAZS: OK, I will correct it. Yes, it is the payload that I want to include in the instance data. I thought that lower level etags/timestamps are returned inside the get-response payload. On re-reading RFC8040 I see my mistake. 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). BALAZS: I will try to reword it to clarify the issue. How about: An instance data set is made up of header part and content-data. The content-data is all data inside the anydata data node. The header part is defined by the -ietf-instance-data module while the content-data is defined by the target YANG modules. The content-data  SHALL contain all data that would be inside the <data> wrapper element of a reply to the <get> operation .   I hope this conveys that content data excludes the <data> wrapper element from the get-reply. 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. BALAZS: You are right, although some attributes might be absent in some use cases.  E.g. namespace as you pointed out is always needed. However e.g. origin may be present if the instance data is a snapshot of the operational datastore, but it may be absent if the instance data is used to document readOnly server capabilities. So I propose to change the text to: Some XML attributes (e.g. metadata like origin) MAY be absent. SW handling YANG Instance data MUST ignore XML attributes unknown to it, allowing them to be used later for other purposes. /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'. BALAZS: I agree that in some use cases a timestamp would be useful e.g. diagnostic data from a real live YANG server. However in other use cases like documenting factory default, defining default configuration to be preloaded or documenting server capabilities I see no need for the timestamp. It is not interesting exactly at which hour/minute/second the server capabilities were documented. So while I would not like to add the timestamp in the draft, the draft documents, that additional metadata like a timestamp may be added to the instance data set. -- Balazs Lengyel Ericsson Hungary Ltd. Senior Specialist Mobile: +36-70-330-7909 email: balazs.leng...@ericsson.com

smime.p7s
Description: S/MIME Cryptographic Signature

_______________________________________________
netmod mailing list
netmod@ietf.org
https://www.ietf.org/mailman/listinfo/netmod