On Wed, Jun 17, 2015 at 02:34:52PM +0200, Ladislav Lhotka wrote:
> 
> > On 17 Jun 2015, at 13:51, Juergen Schoenwaelder 
> > <[email protected]> wrote:
> > 
> > On Wed, Jun 17, 2015 at 01:41:56PM +0200, Ladislav Lhotka wrote:
> >> 
> >> 
> >> Well, but it is exactly what Kent objected against. It is the requirement 
> >> to support “old clients” that causes the trouble here (and elsewhere). If 
> >> client A sets “inactive” somewhere, then the datastore semantics will 
> >> change also for client B that doesn’t understand “inactive” and may be 
> >> wondering why the server ignores his edits.
> >> 
> >> I understand (although RFC 6241 doesn’t say it explicitly) that, unlike 
> >> YANG extensions, a NETCONF capability advertised by the server can be 
> >> mandatory for the client in the sense that it has to understand and honour 
> >> it.
> > 
> > There is no way for a client to tell whether a certain capability URI
> > (it has never seen before) is mandatory to understand or not. In fact,
> 
> So it means that, e.g. the annotations from
> 
> https://tools.ietf.org/html/draft-kwatsen-conditional-enablement-00
> 
> cannot be safely used by the server even after advertising them via 
> :conditional-enablement capability.

Yes, advertisement is not sufficient.

> > Without further protocol support to negotiate annotations, I think
> > annotations must be limited to things that can be safely ignored by a
> > client. I have not read the I-D yet but I would expect that it should
> > say something like that. ;-)
> 
> But it’s not a specific problem of this draft, it would simply mean that 
> annotations that cannot be ignored cannot be used at all, no matter what. 
> However, some annotations that have been proposed (and probably used in the 
> wild) are of that sort.
>

They cannot be used safely until there is an annotation negotiation
mechanism, or as Martin indicated, a way for a client to explicitely
enable the functionality associated with certain annotations.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>

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