Hi Juergen, > -----Original Message----- > From: Juergen Schoenwaelder <[email protected]> > Sent: 24 March 2019 15:31 > To: Rob Wilton (rwilton) <[email protected]> > Cc: Andy Bierman <[email protected]>; NetMod WG <[email protected]> > Subject: Re: [netmod] import-by-semver issue > > On Sun, Mar 24, 2019 at 02:07:15PM +0000, Rob Wilton (rwilton) wrote: > > Hi Andy, > > > > There are many ways to write and design compilers. > > > > Compilers that don’t understand import-by-semver just ignore the extension, > no deviation is required. They just import whichever arbitrary revision that > they > would have imported anyway, as specified by YANG 1.1. The import-by-semver > statement just reduces the set of valid modules revisions that can be used for > import. > > > > If two compilers (one supporting semver, the other not) resolve imports > differently, then the design is in my view somewhat broken, in particular if > you > allow NBC changes.
But that is true of YANG compilers today. If there are multiple revisions of a module that could be chosen, then each compiler is at liberty to decide which revision to choose (last paragraph of section 5.1.1 in RFC 7950). So, I would argue that "import-by-version" doesn't make YANG compilers any less consistent that they are already today, since that inconsistency already exists. I presume that the real solution here is to explicitly define the full set of implemented, import-only-modules to the compiler so that it always compiles a consistent schema. Perhaps other compilers have different ways to solve this problem. Note, I also think that YANG library has a similar inconsistency. I.e. there is no guarantee that two different compilers will construct exactly the same datastore schema from the YANG library output. I think that this is a design bug, but also one that we attempt to address in draft-verdt-netmod-yang-semver-00. Thanks, Rob > > /js > > -- > Juergen Schoenwaelder Jacobs University Bremen gGmbH > Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany > Fax: +49 421 200 3103 <https://www.jacobs-university.de/> _______________________________________________ netmod mailing list [email protected] https://www.ietf.org/mailman/listinfo/netmod
