Re: [netmod] Fwd: New Version Notification for draft-lengyel-netmod-yang-instance-data-01.txt

[Balazs Lengyel <[e-mail]>]

On 6/26/2018 4:07 PM, Robert Wilton wrote:

       7) It might want to include a semantic version number for an
       instance-data-set, depending on whether the YANG versioning discussions
       ends up.

     BALAZS: Yes I would like to. However I am not exactly clear on what does
     backwards compatibility mean for instance data.
     Data MAY NOT be removed or changed only added.  ???
     Who would use the semver numbers ???

What does the version number mean? Every change of instance data in an
instacne-data-set leads to a new version number? What is a bug fix in
this sense? What is a non-backwards compatible change of instance data?
I am left a bit puzzled.

Probably I don't mean semantic version.  But often files have versioning, or
revision, information associated with them.  This can be muxed into the file
name/path, but it also seems like potentially useful metadata, and being
able to handle this generically in a consistent way might be beneficial.

As an example, perhaps the capability information related to S/W release
1.2.4, etc.

We need to separate a version number of the instance data from the a
version number (or version context) that may be needed in order to
understand what a YANG (module, path) tuple means if we move to a
different YANG versioning scheme. The later I agree would be needed,
the former I am less sure of - at least if we talk semantic version
numbers.

Yes, I agree with the need for the latter, that may entail listing the versions of the modules in the meta-data.

But what I was actually referring to was the former, and thinking more of it is just being a string field in the meta-data with a well defined name, that is optional to populate.  Actually, I see the current definition already has a revision with a date and description string.  This is roughly along the lines of what I was thinking of for versioning (although I'm not sure why this should be a list rather than just a pair of leaves).

Thanks,
Rob

BALAZS:  IMHO if we want to use versioning (semver) to version the instance-data-set itself we first need to understand what backwards compatibility means for an instance data set.

Revision is a list because as you develop your instance-data-set you may go through multiple revisions. Just as you may have multiple revision statements in a YANG Module (YAM) the same way you may need multiple revision list entries in an instance data set; to keep history.

(And following your advice, that is one very good reason to define the metadata about the set as normal YANG instead of yang-meta-data which does not have the concept of meta-data-array)
regards Balazs

-- 
Balazs Lengyel                       Ericsson Hungary Ltd.
Senior Specialist
Mobile: [phone]              email: [e-mail]