Re: [i2rs] I2RS Interim Meeting - June 1, 2016 - 10:00am - 11:00am - Topic: Ephemeral State Requirements

[Andy Bierman <[e-mail]>]

On Wed, Jun 1, 2016 at 5:41 AM, Jeffrey Haas <[e-mail]> wrote:

> On Wed, Jun 01, 2016 at 05:08:16AM -0700, Andy Bierman wrote:
> > On Wed, Jun 1, 2016 at 2:10 AM, Juergen Schoenwaelder <
> > [e-mail]> wrote:
> > > On Tue, May 31, 2016 at 03:36:40PM -0400, Jeffrey Haas wrote:
> > > > I agree that your observation covers the general intent.  The
> > > requirements
> > > > language above is attempting to be a bit too specific for a given
> > > > implementation detail, namely instantiation of ephemeral behaviors
> in a
> > > data
> > > > tree.
> > > >
> > > > Could you please supply alternative text?
> > >
> > > It is difficult since I am not sure what the original intention
> > > was. There is augmentation at the schema tree level and then there is
> > > augmentation at the data tree level. My understanding (which may be
> > > wrong) is that I2RS primarily looks at data tree level augmentations
> > > of operational state data and not so much at configuration datastore
> > > data. Part of the openconfig inspired discussion is to do away with
> > > the /foo and /foo-state division and that has an impact how the schema
> > > trees are constructed.
> > >
> > >
> > This REQ-05 doesn't give any reason why data nodes need to be tagged as
> > ephemeral
> > in the schema tree, or what it means to be tagged as ephemeral.
> >
> > My intention for suggesting an "i2rs:ephemeral" YANG extension was to
> > identify
> > the I2RS conformance requirements for a server claiming to implement I2RS
> > for a specific YANG module.
> >
> > A node tagged as ephemeral MUST be accessible in the ephemeral datastore
> > using I2RS if the module (or feature) is supported. An untagged node MAY
> be
> > accessible.
>
> This covers the intent properly.
>
> Your suggestion of a mechanism in yang is probably reasonable, but as
> Jürgen
> would say, this is all about the requirements.  So, could you suggest text
> covering the requirement?
>
>
I thought I just did.


Andy


> > An I2RS data model could define read-only nodes.  These nodes could
> > be considered ephemeral operational state.  Should these nodes live in
> > this datastore or an "operational" datastore?  I don't know.
> > That's why we probably need your draft.
>
> If the implementation detail for ephemeral state is that it is part of a
> datastore, then having the operational state in the ephemeral datastore
> seems to make sense.  However, I find it more likely that we'll need a
> mechanism to get the "union view after precedence" (i.e. panes of glass
> model) for a conceptional datastore that covers state from local and
> ephemeral.
>
> But again, that's a protocol detail which we're trying to avoid in the
> requirements.
>
> If you think it belongs in the strawman or another document, we'd love
> text.
>
> -- Jeff
>