Re: [netmod] ?= ?==?utf-8?q? mandatory choice with non-presence container cas
Ladislav Lhotka <lhotka@nic.cz> Wed, 26 June 2019 07:01 UTC
Return-Path: <lhotka@nic.cz>
X-Original-To: netmod@ietfa.amsl.com
Delivered-To: netmod@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 7BB84120122 for <netmod@ietfa.amsl.com>; Wed, 26 Jun 2019 00:01:19 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.996
X-Spam-Level:
X-Spam-Status: No, score=-6.996 tagged_above=-999 required=5 tests=[BAD_ENC_HEADER=0.001, BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=nic.cz
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8cmwgdMKcg6x for <netmod@ietfa.amsl.com>; Wed, 26 Jun 2019 00:01:16 -0700 (PDT)
Received: from mail.nic.cz (mail.nic.cz [IPv6:2001:1488:800:400::400]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 190281201E8 for <netmod@ietf.org>; Wed, 26 Jun 2019 00:01:15 -0700 (PDT)
Received: from birdie (176.100.broadband6.iol.cz [88.101.100.176]) by mail.nic.cz (Postfix) with ESMTPSA id EC2771409A6; Wed, 26 Jun 2019 09:01:09 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=nic.cz; s=default; t=1561532473; bh=fkjUOUUJT1eAeBWLaIbxGPKZ5K0eTWQo7TMC3v8zRvA=; h=From:To:Date; b=p7ecy6I9DnwP0Gib/wqBHpwgfoowobfox6JYnyWfQtX8x39O6YbIQ1BCgz/LaY3EY zl1SJTIx/jh4pAtJT/YSAvY4huse3OiPwy+7tcje+RjORWRYoDd/VQdx6xO5Mqrnyq ekSLs/cTAGWt9g1riV5JDEWkpl3C3GFuL38vc2SA=
Message-ID: <af287b2bc9850cf902296d8e9748e0651e9ed340.camel@nic.cz>
From: Ladislav Lhotka <lhotka@nic.cz>
To: "Rob Wilton (rwilton)" <rwilton@cisco.com>, "netmod@ietf.org" <netmod@ietf.org>
Date: Wed, 26 Jun 2019 09:01:00 +0200
In-Reply-To: <BYAPR11MB2631B1B25C323764194E7855B5E30@BYAPR11MB2631.namprd11.prod.outlook.com>
References: <BYAPR11MB263192DBFAA0F634DBCF0A85B5E30@BYAPR11MB2631.namprd11.prod.outlook.com> <791d-5d120380-25-51599d00@91535824> <20190625.135902.1021903277794682233.mbj@tail-f.com> <41409287f28be0e30e4bc29ef44f755434f6567f.camel@nic.cz> <BYAPR11MB2631B1B25C323764194E7855B5E30@BYAPR11MB2631.namprd11.prod.outlook.com>
Organization: CZ.NIC
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.32.3
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
X-Virus-Scanned: clamav-milter 0.100.3 at mail.nic.cz
X-Virus-Status: Clean
Archived-At: <https://mailarchive.ietf.org/arch/msg/netmod/mtYANgFJ3q6VefsMYo9knGq9Io0>
Subject: Re: [netmod] ?= ?==?utf-8?q? mandatory choice with non-presence container cas
X-BeenThere: netmod@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: NETMOD WG list <netmod.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/netmod>, <mailto:netmod-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/netmod/>
List-Post: <mailto:netmod@ietf.org>
List-Help: <mailto:netmod-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/netmod>, <mailto:netmod-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 26 Jun 2019 07:01:20 -0000
On Tue, 2019-06-25 at 13:49 +0000, Rob Wilton (rwilton) wrote: > > -----Original Message----- > > From: netmod <netmod-bounces@ietf.org> On Behalf Of Ladislav Lhotka > > Sent: 25 June 2019 14:14 > > To: netmod@ietf.org > > Subject: Re: [netmod] ?= ?==?utf-8?q? mandatory choice with non-presence > > container cas > > > > On Tue, 2019-06-25 at 13:59 +0200, Martin Bjorklund wrote: > > > Michal Vaško <mvasko@cesnet.cz> wrote: > > > > Hi Rob, > > > > actually, I have used model with the container TOP just for > > > > simplification, I have encountered the issue while implementing > > > > ietf-ssh-server model from its current draft. I have created the > > > > container "users" [1] without any "user" list instances. Now, you > > > > may argue that this is still not a valid use-case because there are > > > > no users but I only tried to satisfy the condition. > > > > > > Yes, I think that this list (user) should have a "min-elements 1". I > > > think that matches the i ntent. > > > > Interestingly, the "users" container actually becomes a P-container: its > > presence indicates that the corresponding case is selected. > > I don't think that this makes it a P-container. Not formally, according to the current rules, but effectively "the container itself carries some meaning" (sec. 7.5.1). > > > > It might make > > sense for an admin to select this case even before any users are > > configured. > > Sure, the "users" container could have been marked as having presence in the > YANG model. > > > > This example also exposes the drawback of the XML representation - it > > cannot distinguish between an empty list and nothing. In JSON, the > > problems of this thread could potentially be circumvented by configuring > > > > "users" : { > > "user" : [ > > ] > > } > > I don't think that an empty list "exists" in a configuration datastore, i.e. I I am not sure about this, it possibly depends on an implementation. Lada > don't think that it should impart any meaning, in that regard is seems > somewhat like an NP-container. > > Thanks, > Rob > > > > Lada > > > > > /martin > > > > > > > > > > > > > There are some users > > > > on the system but they are generated into the configuration > > > > on-demand when operational data is requested. > > > > > > > > Regards, > > > > Michal > > > > > > > > [1] > > > > https://tools.ietf.org/html/draft-ietf-netconf-ssh-client-server-14# > > > > page-22 > > > > > > > > On Tuesday, June 25, 2019 11:08 CEST, "Rob Wilton (rwilton)" > > > > <rwilton@cisco.com> wrote: > > > > > > > > > Hi Michal, > > > > > > > > > > It is not the printing of the data that makes it valid/invalid. > > > > > > > > > > I don't think that your input data was ever valid, because > > > > > "container C" doesn't satisfy the mandatory statement because it > > > > > isn't a real data node in the tree - it is instantiated when > > > > > required and may be deleted when it is no longer required. > > > > > > > > > > I.e. your model has been designed such that it can never be > > satisfied. > > > > > > > > > > If your model was instead: > > > > > > > > > > container TOP { > > > > > leaf L { > > > > > type empty; > > > > > } > > > > > choice A { > > > > > mandatory true; > > > > > container C { > > > > > leaf L2 { > > > > > type empty; > > > > > } > > > > > } > > > > > } > > > > > } > > > > > > > > > > > > > > > Then this data is valid: > > > > > > > > > > <TOP> > > > > > <L/> > > > > > <C> > > > > > <L2/> > > > > > </C> > > > > > </TOP> > > > > > > > > > > > > > > > But this data is not: > > > > > > > > > > <TOP> > > > > > <L/> > > > > > </TOP> > > > > > > > > > > > > > > > Nor is this, which is directly equivalent to the one above, > > > > > because the <C/> container doesn't really exist if it doesn't have > > > > > a child node present. > > > > > > > > > > <TOP> > > > > > <L/> > > > > > <C/> > > > > > </TOP> > > > > > > > > > > Thanks, > > > > > Rob > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > From: Michal Vaško <mvasko@cesnet.cz> > > > > > > Sent: 24 June 2019 18:15 > > > > > > To: Andy Bierman <andy@yumaworks.com> > > > > > > Cc: Rob Wilton (rwilton) <rwilton@cisco.com>; netmod > > > > > > <netmod@ietf.org> > > > > > > Subject: Re: [netmod] ?= mandatory choice with non-presence > > > > > > container cas > > > > > > > > > > > > Hi Andy, > > > > > > > > > > > > On Monday, June 24, 2019 19:11 CEST, Andy Bierman > > > > > > <andy@yumaworks.com> > > > > > > wrote: > > > > > > > > > > > > > On Mon, Jun 24, 2019 at 10:01 AM Michal Vaško > > > > > > > <mvasko@cesnet.cz> > > > > > > > wrote: > > > > > > > > > > > > > > > Hi Rob, > > > > > > > > I think there is a problem in the RFC because using only > > > > > > > > allowed steps I got invalid data from initially valid data. > > > > > > > > That cannot be > > > > > > correct. > > > > > > > No. See sec. 7.5.7 > > > > > > > > > > > > > > If a non-presence container does not have any child nodes, > > the > > > > > > > container may or may not be present in the XML encoding. > > > > > > > > > > > > > > > > > > > > > Just because your retrieval does not contain the NP-container, > > > > > > > that does not mean the NP-container was not present in the > > > > > > > server for the mandatory-stmt validation. > > > > > > > > > > > > I agree, but these valid data were correctly printed into > > > > > > invalid data. I do not think printing is allowed to change the > > > > > > validity of data. > > > > > > > > > > > > Michal > > > > > > > > > > > > > Regards, > > > > > > > > Michal > > > > > > > > > > > > > > > > > > > > > > > Andy > > > > > > > > > > > > > > > > > > > > > > On Monday, June 24, 2019 18:52 CEST, "Rob Wilton (rwilton)" > > > > > > > > < rwilton@cisco.com> wrote: > > > > > > > > > > > > > > > > > Hi Michal, > > > > > > > > > > > > > > > > > > My thoughts: > > > > > > > > > > > > > > > > > > According to 7.5.1: > > > > > > > > > > > > > > > > > > In the first style, the container has no meaning of its > > > > > > > > > own, > > > > > > existing > > > > > > > > > only to contain child nodes. In particular, the > > > > > > > > > presence of the > > > > > > > > > container node with no child nodes is semantically > > > > > > > > > equivalent to > > > > > > the > > > > > > > > > absence of the container node. YANG calls this style a > > > > > > > > > "non- > > > > > > presence > > > > > > > > > container". This is the default style. > > > > > > > > > > > > > > > > > > Hence your request (because the NP container does not have > > > > > > > > > any > > > > > > > > > children) > > > > > > > > is equivalent to: > > > > > > > > > <TOP> > > > > > > > > > <L/> > > > > > > > > > </TOP> > > > > > > > > > > > > > > > > > > which fails the "mandatory" check. > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > Rob > > > > > > > > > > > > > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > > > > > From: netmod <netmod-bounces@ietf.org> On Behalf Of > > > > > > > > > > Michal Vaško > > > > > > > > > > Sent: 24 June 2019 17:39 > > > > > > > > > > To: netmod <netmod@ietf.org> > > > > > > > > > > Subject: [netmod] mandatory choice with non-presence > > > > > > > > > > container case > > > > > > > > > > > > > > > > > > > > Hi, > > > > > > > > > > I have encountered a situation that I think is not > > > > > > > > > > covered by RFC > > > > > > > > 7950. My > > > > > > > > > > specific use-case was as follows. > > > > > > > > > > > > > > > > > > > > model: > > > > > > > > > > > > > > > > > > > > container TOP { > > > > > > > > > > leaf L { > > > > > > > > > > type empty; > > > > > > > > > > } > > > > > > > > > > choice A { > > > > > > > > > > mandatory true; > > > > > > > > > > container C; > > > > > > > > > > } > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > data: > > > > > > > > > > > > > > > > > > > > <TOP> > > > > > > > > > > <L/> > > > > > > > > > > <C/> > > > > > > > > > > </TOP> > > > > > > > > > > > > > > > > > > > > Parsing was successful, but printing these data back to > > > > > > > > > > XML > > > > > > produced: > > > > > > > > > > <TOP> > > > > > > > > > > <L/> > > > > > > > > > > </TOP> > > > > > > > > > > > > > > > > > > > > and parsing this correctly failed with missing mandatory > > choice. > > > > > > > > According > > > > > > > > > > to section 7.5.7 [1], I think the C container could be > > > > > > > > > > omitted but the whole situation does not seem correct. > > > > > > > > > > Thank you for any > > > > > > input. > > > > > > > > > > Regards, > > > > > > > > > > Michal > > > > > > > > > > > > > > > > > > > > [1] https://tools.ietf.org/html/rfc7950#section-7.5.7 > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > > > netmod mailing list > > > > > > > > > > netmod@ietf.org > > > > > > > > > > https://www.ietf.org/mailman/listinfo/netmod > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > netmod mailing list > > > > > > > > netmod@ietf.org > > > > > > > > https://www.ietf.org/mailman/listinfo/netmod > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > netmod mailing list > > > > netmod@ietf.org > > > > https://www.ietf.org/mailman/listinfo/netmod > > > > > > _______________________________________________ > > > netmod mailing list > > > netmod@ietf.org > > > https://www.ietf.org/mailman/listinfo/netmod > > -- > > Ladislav Lhotka > > Head, CZ.NIC Labs > > PGP Key ID: 0xB8F92B08A9F76C67 > > > > _______________________________________________ > > netmod mailing list > > netmod@ietf.org > > https://www.ietf.org/mailman/listinfo/netmod -- Ladislav Lhotka Head, CZ.NIC Labs PGP Key ID: 0xB8F92B08A9F76C67
- [netmod] mandatory choice with non-presence conta… Michal Vaško
- Re: [netmod] mandatory choice with non-presence c… Rob Wilton (rwilton)
- Re: [netmod] ?==?utf-8?q? mandatory choice with n… Michal Vaško
- Re: [netmod] ?==?utf-8?q? mandatory choice with n… Andy Bierman
- Re: [netmod] ?==?utf-8?q? ?==?utf-8?q? ?= mandato… Michal Vaško
- Re: [netmod] ?==?utf-8?q? mandatory choice with n… Qin Wu
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Kent Watsen
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Ladislav Lhotka
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Martin Bjorklund
- Re: [netmod] ?= mandatory choice with non-presenc… Rob Wilton (rwilton)
- Re: [netmod] ?==?utf-8?q? ?==?utf-8?q? ?= mandato… Michal Vaško
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Ladislav Lhotka
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Martin Bjorklund
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Ladislav Lhotka
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Rob Wilton (rwilton)
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Ladislav Lhotka
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Rob Wilton (rwilton)
- Re: [netmod] ?= ?==?utf-8?q? mandatory choice wit… Christian Hopps