If compilers can pick different revisions and this results in different interpretations of YANG definitions then thigns are broken.
/js On Wed, Nov 15, 2023 at 10:30:49PM +0000, Jason Sterne (Nokia) wrote: > Hi all, > > A poll at IETF118 was roughly split on recommended-min. > > We discussed this in the weekly YANG versioning call and feel we should: > 1) keep recommended-min-date in the Module Versioning draft > 2) add recommended-min-label (or similar name) in the YANG Semver draft. > They would be mutually exclusive inside a single import statement. > > As defined in Module Versioning, the recommended-min is informational only. > Compilers/tools are not required to use the recommended-min as a constraint. > > We don't believe this causes any new incompatibility issues wrt RFC7950. > > RFC7950 section 5.1.1 says the following: > > If a module is not imported with a specific revision, it is undefined > which revision is used. > > So clients, servers and tools can pick whatever revision they want. Two > different tools may pick different revisions. > > In section 5.6.5 RFC7950 says the following: > > If a server lists a module C in the "/modules-state/module" list from > "ietf-yang-library" and there are other modules Ms listed that import > C without specifying the revision date of module C, the server MUST > use the definitions from the most recent revision of C listed for > modules Ms. > > Recommended-min does not affect conformance and is not mandatory. So a > server, toolchain, etc can continue to select the "most recent revision" even > if that revision is older than the recommended-min. > > Jason > > > > -----Original Message----- > > From: Jürgen Schönwälder <[email protected]> > > Sent: Thursday, October 26, 2023 4:23 AM > > To: Andy Bierman <[email protected]> > > Cc: Joe Clarke (jclarke) <[email protected]>; Jason Sterne > > (Nokia) <[email protected]>; [email protected] > > Subject: Re: [netmod] Updated Content of Module Versioning - T8 > > (recommended-min for imports) > > > > > > CAUTION: This is an external email. Please be very careful when clicking > > links or > > opening attachments. See the URL nok.it/ext for additional information. > > > > > > > > Well, yes, import-by-revision is broken. However, changing the way how > > imports work changes the YANG language. So it is important to know > > which version of the YANG language tools implement. For this we have > > language version numbers. > > > > /js > > > > On Wed, Oct 25, 2023 at 02:44:26PM -0700, Andy Bierman wrote: > > > On Wed, Oct 25, 2023 at 12:03 PM Joe Clarke (jclarke) <jclarke= > > > [email protected]> wrote: > > > > > > > This is the reason that, for me, I’d want the extension to be outside > > > > the > > > > description in something that is machine-readable. Tools that do > > > > understand this extension could make a better decision about which > > > > module > > > > revision to use. > > > > > > > > > > > > > > > > > > +1 > > > > > > The YANG author should know if their module depends on imported > > > definitions > > > from a specific revision. > > > IMO the min-revision is needed in this case, and SHOULD be present. > > > There is a big difference between "module will compile" and "module will > > > work as intended". > > > > > > Tools that do not understand the extension will resolve the import as they > > > > normally would, which may lead to a failure at compile time (e.g., for a > > > > missing node). > > > > > > > > > > This extension MUST be ignored if the 'revision-date' statement is present > > > in the import-stmt. > > > > > > > > > > > > > > Joe > > > > > > > > > > Andy > > > > > > > > > > > > > > > > > > *From: *netmod <[email protected]> on behalf of Jürgen > > Schönwälder > > > > <[email protected]> > > > > *Date: *Wednesday, October 25, 2023 at 14:45 > > > > *To: *Jason Sterne (Nokia) <[email protected]> > > > > *Cc: *[email protected] <[email protected]> > > > > *Subject: *Re: [netmod] Updated Content of Module Versioning - T8 > > > > (recommended-min for imports) > > > > > > > > I am strongly against this. The import statement is used by tools. > > > > Adding a recommendation for humans that existing and conforming tools > > > > will not understand just causes confusion. > > > > > > > > /js > > > > > > > > On Wed, Oct 25, 2023 at 06:41:19PM +0000, Jason Sterne (Nokia) wrote: > > > > > Hi all, > > > > > > > > > > Starting a dedicated thread for T8 recommended-min for imports > > > > > > > > > > These are my own personal opinions (not those of the > > > > authors/contributors). > > > > > > > > > > It has been discussed before that import by a specific revision is > > > > somewhat broken (not recommended). It is mentioned in section 2.5 of the > > > > versioning requirements draft: > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Farchive%2Fid%2Fdraft-ietf-netmod-yang-versioning-reqs-&data=05%7C01%7Cjschoenwae%40constructor.university%7Cb1d7ba4086994666f7bc08dbe62a895f%7Cf78e973e5c0b4ab8bbd79887c95a8ebd%7C0%7C0%7C638356842599181819%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=mToffeBs6EqTWG6FnQzemM4cQlx7PdN%2BCK2ldHUxMYg%3D&reserved=0 > > 08.html#name-no-good-way-to-specify-whic > > > > > > > > > > Based on previous WG LC discussions, we already changed from a > > > > revision-or-derived extension (that did affect conformance & what a tool > > > > could/should use), to a weaker recommended-min in order to avoid further > > > > changes to the YANG language & conformance rules. The recommended-min > > is > > > > pretty much purely a documentation tag that helps users of the modules > > > > understand what versions of imports might be best to use (e.g. when > > > > supporting multiple modules in a server, or constructing a "package" of > > > > modules that work together). > > > > > > > > > > We could instead just say to put this information into a description > > > > field in the module. But it is helpful if the field is broken out (i.e. > > > > structured data) and more easily machine readable. > > > > > > > > > > So I'd like to see this stay as part of Module Versioning but be > > > > > renamed > > > > to recommended-min-date. Then in YANG Semver we should add > > > > recommended-min-semver-label. > > > > > > > > > > Jason > > > > > > > > > > > > > > > From: netmod <[email protected]> On Behalf Of Jason Sterne > > (Nokia) > > > > > Sent: Tuesday, October 24, 2023 9:58 AM > > > > > To: [email protected] > > > > > Subject: [netmod] Updated Content of Module Versioning > > > > > > > > > > Hello NETMOD WG, > > > > > > > > > > The YANG versioning authors and weekly call group members have been > > > > discussing the next steps for the versioning drafts. > > > > > > > > > > We'd propose that the first step is to converge on what aspects of the > > > > current Module Versioning draft should be retained, and which parts > > > > should > > > > be removed. We can then work towards a final call on an updated version > > > > with this revised scope. > > > > > > > > > > Below is a summary of the main topics in the Module Versioning draft. > > > > We've divided the items T1-T10 into 2 groups: > > > > > A) Baseline content of Module Versioning > > > > > B) Items which need more WG discussion > > > > > > > > > > In addition to whatever discussions happen on this email list, we have > > > > also created a hedgedoc where you can register your preference for items > > > > T7-T10. It would be much appreciated if you can put your opinion in the > > > > hedgedoc here: > > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnotes.ietf.org%2FCdKrT5kVSF6qbnRSY4KeSA%3Fboth&data=05%7C01%7Cjschoenwae%40constructor.university%7Cb1d7ba4086994666f7bc08dbe62a895f%7Cf78e973e5c0b4ab8bbd79887c95a8ebd%7C0%7C0%7C638356842599181819%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=TLBU8t%2BDky6T9wHbWtix699ImOUayYFVaIPC7EVQNTA%3D&reserved=0 > > > > > > > > > > > > > > > GROUP A (Baseline content of Module Vesioning) > > > > > ----------------------------------------------------------------- > > > > > Based on resolution of WG LC comments and subsequent discussions, and > > > > some feedback to reduce complexity and content in the Module Versioning > > > > draft, here is a summary of items that will and won't be part of the > > > > next > > > > update of the Module Versioning draft (also referred to as "this draft" > > > > below). > > > > > > > > > > T1. The "ver:non-backwards-compatible" annotation (Sec 3.2): > > > > > Retained. This top level (module level) extension (which can be > > > > > ignored > > > > by tools that don't understand it) is critical to include so that module > > > > readers and tools can know when NBC changes have occurred. > > > > > > > > > > T2. Updated rules of what is NBC: (Sect 3.1.1, 3.1.2) > > > > > Retained. These are updates/clarifications (i.e., changes) to the RFC > > > > 7950 rules that are appropriate and helpful: > > > > > (i) "status obsolete" > > > > > - This draft changes RFC 7950 so that marking a data node as > > > > > obsolete > > > > is an NBC change because it can break clients. > > > > > (ii) "extensions" > > > > > - This draft changes the RFC 7950 rules to allow extensions to > > > > > define > > > > the backwards compatibility considerations for the extension itself. > > > > The > > > > existing RFC 7950 rules only allow extensions to be added, not changed > > > > or > > > > removed. > > > > > (iii) "import by revision-date" > > > > > - This draft changes the RFC 7950 rules to allow the revision date > > > > > of > > > > an import-statement to be changed/added/removed. The imported module > > must > > > > be versioned separately (i.e., by a YANG package/library defining the > > > > schema). > > > > > (iv) "whitespace": > > > > > - This draft clarifies the existing RFC 7950 behaviour that changing > > > > insignificant whitespace is classified as a backwards compatible change > > > > > > > > > > T3. revision-label-scheme extension (Sec 3.4.2) > > > > > Removed. Based on WG LC discussions we will go back to a single > > > > versioning scheme for YANG modules, and hence the revision-label-scheme > > > > extension will be removed from this draft. > > > > > > > > > > T4. revision-label extension (Sec 3.4) > > > > > Removed. Related to T3 above, given that a single versioning scheme is > > > > sufficient, the revision-label extension will be moved to the YANG > > > > Semver > > > > draft, and removed from Module Versioning. > > > > > > > > > > T5. Resolving ambiguous imports in YANG library (Sec 5.1) > > > > > Removed. This will be removed from Module Versioning (could be > > > > considered in YANG Next, although that is many years away). Note, RFC > > > > 7950, section 5.6.5, paragraph 5 does consistently define how to build > > > > the > > > > schema. The change in the draft was to always prioritise an implemented > > > > module over the most recent implemented *or* import-only revision. But > > > > this > > > > will be removed. > > > > > > > > > > T6. Advertisement for how deprecated & obsolete nodes are handled (Sec > > > > 5.2.2) > > > > > Retained. This information is important for clients to be able to > > > > accurately construct the schema and hence it is retained in Module > > > > Versioning. > > > > > > > > > > GROUP B (Needs WG discussion) > > > > > ------------------------------------------- > > > > > For these items we don't have consensus within the WG - they need more > > > > discussion and input. > > > > > > > > > > It is recommended to go back and look at the NETMOD emails on these > > > > topics (from the WG LC discussions). > > > > > > > > > > Please add your name beside your preferred option in the poll: > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnotes.ietf.org%2FCdKrT5kVSF6qbnRSY4KeSA%3Fboth&data=05%7C01%7Cjschoenwae%40constructor.university%7Cb1d7ba4086994666f7bc08dbe62a895f%7Cf78e973e5c0b4ab8bbd79887c95a8ebd%7C0%7C0%7C638356842599181819%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=TLBU8t%2BDky6T9wHbWtix699ImOUayYFVaIPC7EVQNTA%3D&reserved=0 > > > > > > > > > > T7. filename changes (Sec 3.4.1) > > > > > The authors/contributors are leaning towards suggesting that this > > > > > moved > > > > change be moved to YANG Next consideration. However, there isn't > > > > complete > > > > consensus, with concerns that the vendors will each define their own > > > > incompatible file naming schemes for YANG modules that use version > > > > numbers. If we retain this work then this would likely move to the YANG > > > > Semver draft. > > > > > [See hedgedoc poll T7] > > > > > > > > > > T8. recommended-min for imports (Sec 4) > > > > > The WG seems to be somewhat split on how urgent this is, and there > > > > > isn't > > > > consensus amongst authors/contributors for retaining this work or > > > > deferring > > > > it. One option is to keep it, but renamed as recommended-min-date. > > > > > [See hedgedoc poll T8] > > > > > > > > > > T9. Versioning of YANG instance data (Sec 6) > > > > > There wasn't any consensus among the authors/contributors as to > > > > > whether > > > > this should be retained or deferred to a new version of the YANG > > > > instance > > > > data document. > > > > > [See hedgedoc poll T9] > > > > > > > > > > T10. Do *all* whitespace changes (including whitespace between > > > > statements) require a new revision to be published? Sec 3.1, last > > > > paragraph. > > > > > The authors/contributors are somewhat split on whether to retain this. > > > > The advantage of keeping this is that it makes it very easy to check > > > > (i.e., > > > > via a simple text diff tool) whether two modules pertaining to be the > > > > same > > > > version are in fact the same. It should also mean that it is easy to > > > > generate a hash-based fingerprint of a module revision. The alternative > > > > gives more flexibility to users to reformat modules (e.g., for different > > > > line-lengths), but complicates the check to ensure that a YANG module > > > > revision hasn't been changed or makes it slightly more expensive to > > > > generate a hash since the module formatting would need to be normalized > > > > first. > > > > > [See hedgedoc poll T10] > > > > > > > > > > Jason (he/him) > > > > > > > > > > > > > > _______________________________________________ > > > > > netmod mailing list > > > > > [email protected] > > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Fmailman%2Flistinfo%2Fnetmod&data=05%7C01%7Cjschoenwae%40constructor.university%7Cb1d7ba4086994666f7bc08dbe62a895f%7Cf78e973e5c0b4ab8bbd79887c95a8ebd%7C0%7C0%7C638356842599181819%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=P8IzGqzGsqheqNe%2BcIEUtE1e4hdJNG1I7Amo%2BryWPM0%3D&reserved=0 > > > > > > > > > > > > -- > > > > Jürgen Schönwälder Constructor University Bremen gGmbH > > > > Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany > > > > Fax: +49 421 200 3103 > > > > <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fconstructor.university%2F&data=05%7C01%7Cjschoenwae%40constructor.university%7Cb1d7ba4086994666f7bc08dbe62a895f%7Cf78e973e5c0b4ab8bbd79887c95a8ebd%7C0%7C0%7C638356842599181819%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=TmXcqltoqstXmxR52%2BOh8yEwk3B2oi4EGMb%2FIgxMSnU%3D&reserved=0> > > > > > > > > _______________________________________________ > > > > netmod mailing list > > > > [email protected] > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Fmailman%2Flistinfo%2Fnetmod&data=05%7C01%7Cjschoenwae%40constructor.university%7Cb1d7ba4086994666f7bc08dbe62a895f%7Cf78e973e5c0b4ab8bbd79887c95a8ebd%7C0%7C0%7C638356842599181819%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=P8IzGqzGsqheqNe%2BcIEUtE1e4hdJNG1I7Amo%2BryWPM0%3D&reserved=0 > > > > _______________________________________________ > > > > netmod mailing list > > > > [email protected] > > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Fmailman%2Flistinfo%2Fnetmod&data=05%7C01%7Cjschoenwae%40constructor.university%7Cb1d7ba4086994666f7bc08dbe62a895f%7Cf78e973e5c0b4ab8bbd79887c95a8ebd%7C0%7C0%7C638356842599181819%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=P8IzGqzGsqheqNe%2BcIEUtE1e4hdJNG1I7Amo%2BryWPM0%3D&reserved=0 > > > > > > > > -- > > Jürgen Schönwälder Constructor University Bremen gGmbH > > Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany > > Fax: +49 421 200 3103 > > <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fconstructor.university%2F&data=05%7C01%7Cjschoenwae%40constructor.university%7Cb1d7ba4086994666f7bc08dbe62a895f%7Cf78e973e5c0b4ab8bbd79887c95a8ebd%7C0%7C0%7C638356842599181819%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=TmXcqltoqstXmxR52%2BOh8yEwk3B2oi4EGMb%2FIgxMSnU%3D&reserved=0> -- Jürgen Schönwälder Constructor University Bremen gGmbH Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany Fax: +49 421 200 3103 <https://constructor.university/> _______________________________________________ netmod mailing list [email protected] https://www.ietf.org/mailman/listinfo/netmod
