Robert Wilton <[email protected]> wrote:
> Hi,
> 
> On 05/02/2016 17:34, Juergen Schoenwaelder wrote:
> > On Fri, Feb 05, 2016 at 05:22:03PM +0000, Robert Wilton wrote:
> >> 2. Personally, for a datastore solution, I would prefer if the new
> >> datastore was for the intended configuration, and that the applied
> >> configuration was stored in the same datastore (running?) as all the
> >> rest of the operational state.
> > The running datastore is a configuration datastore, it does not hold
> > operational state.
> OK.  Thanks for the clarification.  I hadn't realised that the
> definition of datastores only applies to configuration and not to
> state!

No, this is not correct.  RFC 6241 defines both "datastore" and
"configuration datastore".  However, "running" is a "configuration
datastore".


/martin


> So, am I right in saying that this draft is effectively reclassifying
> that definition somewhat - given that applied configuration is being
> defined as operational state (at least in the diagram in section
> 3. Conceptual model) and datastores don't store state data?
> 
> 
> >> If the logical flows of system information is as follows:
> >>   [candidate] -> intended cfg -> applied cfg -> derived state
> >>
> >> Then it seems strange to bundle intended cfg & derived state together
> >> in
> >> one datastore, and to have applied-cfg separate (a bit like an
> >> unwanted
> >> step child).
> > This is not what is being proposed. We always had
> >
> > [candidate] -> [running] -> operational state
> >
> > (and I mark configuration data stores in []). Both [candidate] and
> > [running] have the same configuration data model. Now we are asked
> > to expose that [running] may not be applied synchronously and hence
> >
> > [candidate] -> [running] -> [applied] -> derived state
> >
> > seems to make sense.
> >> 5. Am I correct to presume that this draft doesn't provide any support
> >> to return intended config, applied config & derived state all in a
> >> single request?  I appreciate that this isn't included as a formal
> >> requirement - but part of me wonders whether this might have been an
> >> oversight in the requirements.
> > Can be defines easily as another RPC. That said, I heard that some big
> > vendors even refuse to implement today's get operation that returns
> > the combination of [running] and operational state.
> OK, but the key question is what does that returned data look like:
> Are the intended and applied config nodes going to be co-located in
> the same structure or is the response going to be two separate trees
> and for it to be up to the client to merge them together?
> 
> >   
> >> 6. I can understand the decision of get-diff to reuse edit-config or
> >> YANG patch,  but I'm not sure that this makes it particularly easy for
> >> clients to then process that data.  I might be wrong, but I suspect
> >> that
> >> a solution that returns the values of the intended and applied config
> >> nodes in an easier to relate way may be preferable (perhaps something
> >> along the lines of the encoding proposed in
> >> draft-wilton-netmod-opstate-yang).
> > A diff is a way to make delta's efficient.
> Yes, but often diffs include both the old and the new values to make
> it easier to see what the change is (or certainly they do whenever I
> review code diffs).
> 
> I don't think that the YANG patch/edit-config encoding is
> significantly more efficient that the encoding that I suggested, so I
> don't think that efficiency of encoding is a strong argument here.
> 
> The strongest argument for edit-config and YANG patch is that it is
> reusing an existing solution rather than inventing a new way of doing
> this.  But I still think that my observation that this doesn't make it
> particularly easy for clients is valid, and other ways of encoding the
> data could make it easier and more useful.
> 
> Rob
> 
> 
> > /js
> >
> 
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