Juergen Schoenwaelder <[email protected]> writes: > On Tue, Aug 02, 2016 at 01:12:34PM +0200, Ladislav Lhotka wrote: >> >> Yes, but if the YANG version is bumped, the client can immediately see >> that it is not compatible, and disconnect. In contrast, sec. 6.3.1 says >> that an extension "MAY be ignored in its entirety". According to the >> RFC 2119 semantics, doing so should not affect interoperability, which >> is clearly not the case here. >> > > This is apparently where views substantially differ; I do not consider > it an interoperability failure if an old client does not understand a > part of a datamodel of an updated server that the old client is not > dealing with. For me, interoperability means that a server can upgrade > while old clients continue to function as they did before. For me, > interoperability does not mean that server and clients always have to > be updated at the same time and it does not mean that a client needs > to understand and support the entire set of datamodels exposed by a > server.
If this was the only aspect of interoperability, then the best data model would perhaps be just anydata at the top and nothing else. In my view, it is the information from the data model that reduces entropy and thus increases interoperability. Of course, it depends on the purpose of the client but, in general, a client that understands only a part of the data model is less interoperable with the given server than a client that understands it fully. Notwithstanding terminology, I think it is rather important to keep YANG extensions strictly optional because otherwise we will see vendor extensions that effectively limit the choice of clients and management systems. Lada > > /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/> -- Ladislav Lhotka, CZ.NIC Labs PGP Key ID: E74E8C0C _______________________________________________ netmod mailing list [email protected] https://www.ietf.org/mailman/listinfo/netmod
