Re: [netmod] Text in import to indicate whether a module is needed as import-only or as implemented
Andy Bierman <andy@yumaworks.com> Wed, 08 January 2020 12:50 UTC
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From: Andy Bierman <andy@yumaworks.com>
Date: Wed, 08 Jan 2020 04:49:52 -0800
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To: Ladislav Lhotka <lhotka@nic.cz>
Cc: Balázs Lengyel <balazs.lengyel@ericsson.com>, Martin Bjorklund <mbj@tail-f.com>, "netmod@ietf.org" <netmod@ietf.org>
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Subject: Re: [netmod] Text in import to indicate whether a module is needed as import-only or as implemented
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On Wed, Jan 8, 2020 at 1:11 AM Ladislav Lhotka <lhotka@nic.cz> wrote: > On Tue, 2020-01-07 at 14:29 +0000, Balázs Lengyel wrote: > > If that is the consensus, I can remove the description statements, no big > > deal. (I actually like the statements, but they are not important for > this > > draft) > > Of course, it is not that important, but I don't see how this information > could > be harmful, if it is included with the import. In my view, it is not meant > as a > conformance requirement but just an info from the module author about the > meaning of the import statement. > > It adds a lot of extra work but more importantly the import-stmt is the wrong place to document such a complex and unrelated issue as server conformance requirements. The root of this problem (and design flaw of YANG, IMO) is that import is > "overloaded" with two different purposes, one of which effectively > requires that > the imported module be also implemented, while the other doesn't. > > The import-stmt is only used to map a local prefix to an external module. This proposal to add conformance info the the import-stmt would overload it with another purpose. Not even a typedef is easy to classify (e.g., leafref requires implementation of a data node). I certainly agree that YANG conformance is poorly specified, poorly understood, and in real need of improvement. Likewise, the import-stmt is also in need of some improvement since import-by-exact-revision is (and has always been) poorly designed. Lada > > > Balazs > Andy > > > > -----Original Message----- > > From: Martin Bjorklund <mbj@tail-f.com> > > Sent: Tuesday, January 7, 2020 2:38 PM > > To: Balázs Lengyel <balazs.lengyel@ericsson.com> > > Cc: andy@yumaworks.com; lhotka@nic.cz; netmod@ietf.org > > Subject: Re: [netmod] Text in import to indicate whether a module is > needed as > > import-only or as implemented > > > > Hi > > > > I agree w/ Andy and others that we should not add this to the import's > > description. I don't think this kind of conformance text belongs to the > > import's description. If you think it is important to state this, the > best > > place is probably as plain text in the document itself. > > > > > > > > /martin > > > > > > Balázs Lengyel <balazs.lengyel=40ericsson.com@dmarc.ietf.org> wrote: > > > As a draft author who was asked to add text about the imports IMHO > > > > > > * it would be easy for me to remove the description from the import. > > > Actually I really just want to know what is acceptable to the group, > so I > > > can proceed > > > * I also think that adding this text is in most cases easy and it > does not > > > need updates later. > > > * The rules in some cases might not be trivial. > > > > > > * Imported YAMs need to be implemented if > > > > > > * Imported parts are included in Xpath (augment, when, must, require- > > > instance) > > > > > > * Imported YAMs do not need to be implemented if only the following > are > > > used > > > > > > * Types > > > * Features > > > * extensions > > > > > > * Ambiguous if > > > > > > * groupings are used > > > * if the dependency is not formally defined by YANG, but functionally > > > needed. (E.g. notification-capabilities does not formally need > YANG-Push to > > > be implemented, however there is no sense in defining capabilities if > YANG- > > > Push is itself not implemented.) > > > * deviation ? > > > * other cases ? > > > > > > Regards Balazs > > > > > > > > > > > > From: netmod <netmod-bounces@ietf.org> On Behalf Of Andy Bierman > > > Sent: 2019. december 19., csütörtök 17:23 > > > To: Ladislav Lhotka <lhotka@nic.cz> > > > Cc: NetMod WG <netmod@ietf.org> > > > Subject: Re: [netmod] Text in import to indicate whether a module is > > > needed as import-only or as implemented > > > > > > > > > > > > > > > > > > > > > > > > On Thu, Dec 19, 2019 at 8:00 AM Ladislav Lhotka <lhotka@nic.cz > <mailto: > > > lhotka@nic.cz> > wrote: > > > > > > On Thu, 2019-12-19 at 07:52 +0000, Schönwälder, Jürgen wrote: > > > > On Thu, Dec 19, 2019 at 08:23:27AM +0100, Ladislav Lhotka wrote: > > > > > I don't see how YANG syntax defines this. If a module imports > > > > > ietf-netconf- acm, it could be because > > > > > > > > > > - it just uses a typedef, such as "node-instance-identifier", and > then > > > > > ietf-netconf-acm needn't be implemented (but can be), > > > > > > > > > > or > > > > > > > > > > - it augments ietf-netconf-acm, which makes sense only if the > latter > > > > > module is implemented. > > > > > > > > > > It it the YANG library that specifies whether a module is > > > > > implemented or not, but the "import" statement itself doesn't tell > you > > > > > anything. > > > > > > > > > > > > > Can we not assume that an implementor will figure out the difference? > > > > > > An implementor should be able to figure it out, but other potential > > > module users may not. For example, if somebody is evaluating whether > > > to use a module for their device or not, it is important to know that > > > NACM has to be implemented (or not). > > > > > > > > > > > > You seem to be talking about a new conformance documentation procedure > > > > > > that attempts to solve the problem "to use modules A, B, and C > > > together > > > > > > to achieve some functionality X, all these conditions need to be met".. > > > > > > (Sounds more like a problem for YANG Packages to solve) > > > > > > > > > > > > IMO this is a much harder problem than something that can be solved > > > > > > with extra description-stmt text. The writer is likely to get it wrong > > > or not > > > > > > keep it up to date, so a tool to analyze the file seems like a better > > > solution. > > > > > > > > > > > > Lada > > > > > > > > > > > > > > > > > > Andy > > > > > > > > > > > > > > > > Or someone writes a pyang plugin to determine from the schema tree > > > > the kind of imports there are (for a given set of features). > > > > > > > > /js > > > > > > > -- > > > Ladislav Lhotka > > > Head, CZ.NIC Labs > > > PGP Key ID: 0xB8F92B08A9F76C67 > > > > > > _______________________________________________ > > > netmod mailing list > > > netmod@ietf.org <mailto:netmod@ietf.org> > > > https://www.ietf.org/mailman/listinfo/netmod > > > > -- > Ladislav Lhotka > Head, CZ.NIC Labs > PGP Key ID: 0xB8F92B08A9F76C67 > >
- Re: [netmod] Text in import to indicate whether a… Balázs Lengyel
- Re: [netmod] Text in import to indicate whether a… Martin Bjorklund
- [netmod] Text in import to indicate whether a mod… Balázs Lengyel
- Re: [netmod] Text in import to indicate whether a… Andy Bierman
- Re: [netmod] Text in import to indicate whether a… Ladislav Lhotka
- Re: [netmod] Text in import to indicate whether a… Schönwälder
- Re: [netmod] Text in import to indicate whether a… Ladislav Lhotka
- Re: [netmod] Text in import to indicate whether a… Andy Bierman
- Re: [netmod] Text in import to indicate whether a… Balázs Lengyel
- Re: [netmod] Text in import to indicate whether a… Ladislav Lhotka
- Re: [netmod] Text in import to indicate whether a… Andy Bierman
- Re: [netmod] Text in import to indicate whether a… Ladislav Lhotka
- Re: [netmod] Text in import to indicate whether a… Andy Bierman
- Re: [netmod] Text in import to indicate whether a… Benoit Claise
- Re: [netmod] Text in import to indicate whether a… Andy Bierman
- Re: [netmod] Text in import to indicate whether a… Ladislav Lhotka
- Re: [netmod] Text in import to indicate whether a… Andy Bierman
- Re: [netmod] Text in import to indicate whether a… Schönwälder, Jürgen
- Re: [netmod] Text in import to indicate whether a… Benoit Claise
- Re: [netmod] Text in import to indicate whether a… Andy Bierman
- Re: [netmod] Text in import to indicate whether a… Balázs Lengyel
- Re: [netmod] Text in import to indicate whether a… Andy Bierman
- Re: [netmod] Text in import to indicate whether a… Balázs Lengyel
- Re: [netmod] Text in import to indicate whether a… Andy Bierman