Re: [netmod] Obsolete feature - what does it mean?
Kent Watsen <kent@watsen.net> Wed, 27 February 2019 18:17 UTC
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From: Kent Watsen <kent@watsen.net>
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Date: Wed, 27 Feb 2019 18:17:09 +0000
In-Reply-To: <20190227164816.tlfqg4voabtdk7ey@anna.jacobs.jacobs-university.de>
Cc: Balázs Lengyel <balazs.lengyel@ericsson.com>, "netmod@ietf.org" <netmod@ietf.org>
To: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
References: <d0f6a34d-9218-b09b-5e9c-1747b1b780dc@ericsson.com> <20190227103303.emm3xj372rb7fx7t@anna.jacobs.jacobs-university.de> <2035f82c-bc0c-e5bb-40f2-efa6dcef6bde@ericsson.com> <010001692fb7a0c6-9a9ecc8c-f0b0-413c-92eb-30ea0d4b1834-000000@email.amazonses.com> <20190227164816.tlfqg4voabtdk7ey@anna.jacobs.jacobs-university.de>
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Subject: Re: [netmod] Obsolete feature - what does it mean?
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> On Feb 27, 2019, at 11:48 AM, Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> wrote: > > On Wed, Feb 27, 2019 at 04:09:17PM +0000, Kent Watsen wrote: >> >> >>> On Feb 27, 2019, at 6:16 AM, Balázs Lengyel <balazs.lengyel@ericsson.com> wrote: >>> >>> feature oldFeature { >>> status obsolete; >>> } >>> leaf myTimer { >>> if-feature oldFeature ; >>> mandatory true; >>> config true; >>> status current; >>> type string; >>> } >>> So should I configure myTimer or not? I assume yes, correct? >> >> This issue is captured here: https://github.com/netmod-wg/yang-next/issues/27, which was updated as of this morning with this very example. >> >> Of course, the problem is in RFC 7950: >> >> o "obsolete" means that the definition is obsolete and SHOULD NOT be >> implemented and/or can be removed from implementations. >> >> I recommend replacing "SHOULD NOT be implemented" with "is not implemented". > > When an IETF WG decides to obsolete something, I am forced to break > old clients because of this decision? Note sure this makes business > sense (says an academic). > > There is a huge difference between modules where the implementors have > change control over the modules and modules where change control is > far outside the implementors hands and where clients and servers are > implemented by different organizations in an open and largely > uncoordinated way. We always have to keep this in mind when we create > rules. > > The SHOULD NOT allows a server implementor to take a well-informed > decision that there are old clients you care about and that this makes > a business case for supporting obsolete definitions on a server. > > Another aspect here is that we do not make a clear distinction between > server and client. It can very well be that "deprecated" and > "obsolete" mean slightly different things to servers and > clients. (Servers tend to have a natural desire to not break clients > unnecessarily.) But a server can choose to not implement that revision of the module or, with https://github.com/netmod-wg/yang-next/issues/63 <https://github.com/netmod-wg/yang-next/issues/63> deviate the "status" statement. I want "obsolete" to mean as it does everywhere else: out of use, no longer supported, not expected to work, etc. Perhaps there is a line between having "status obsolete" versus disappearing the node altogether? Maybe within the same "major" version (to use a sem-ver term), "obsolete" leaves it to the server's discretion, whereas the next major version disappears the node? If so, then there should be a way for the server to indicate which discretionary choices it made. I'd suggest that "obsolete" defaults to "not-implemented" and thus only servers that want to continue support for the node need to indicate anything. A deviation would be a good fit for this. Kent // contributor
- [netmod] Obsolete feature - what does it mean? Balázs Lengyel
- Re: [netmod] Obsolete feature - what does it mean? Juergen Schoenwaelder
- Re: [netmod] Obsolete feature - what does it mean? Balázs Lengyel
- Re: [netmod] Obsolete feature - what does it mean? Juergen Schoenwaelder
- Re: [netmod] Obsolete feature - what does it mean? Kent Watsen
- Re: [netmod] Obsolete feature - what does it mean? Juergen Schoenwaelder
- Re: [netmod] Obsolete feature - what does it mean? Andy Bierman
- Re: [netmod] Obsolete feature - what does it mean? Kent Watsen
- Re: [netmod] Obsolete feature - what does it mean? Randy Presuhn
- Re: [netmod] Obsolete feature - what does it mean? Kent Watsen
- Re: [netmod] Obsolete feature - what does it mean? Rob Wilton (rwilton)
- Re: [netmod] Obsolete feature - what does it mean? Rob Wilton (rwilton)