Re: [yang-doctors] [netmod] Clarification needed for YANG 1.1 XPATH context
Ladislav Lhotka <lhotka@nic.cz> Fri, 13 April 2018 15:00 UTC
Return-Path: <lhotka@nic.cz>
X-Original-To: yang-doctors@ietfa.amsl.com
Delivered-To: yang-doctors@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 8F3CB126CC7; Fri, 13 Apr 2018 08:00:52 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -7
X-Spam-Level:
X-Spam-Status: No, score=-7 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_HI=-5] 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 yy3KinkGOBax; Fri, 13 Apr 2018 08:00:49 -0700 (PDT)
Received: from mail.nic.cz (mail.nic.cz [217.31.204.67]) (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 6FFC1124BE8; Fri, 13 Apr 2018 08:00:49 -0700 (PDT)
Received: from birdie (unknown [IPv6:2001:1488:fffe:6:2ca5:7aff:fe82:b795]) by mail.nic.cz (Postfix) with ESMTPSA id 8EF486239C; Fri, 13 Apr 2018 17:00:47 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=nic.cz; s=default; t=1523631647; bh=gCcI1ln/CrekLu8r96tV8Bqkiu942srz2pEKoRYDTjU=; h=From:To:Date; b=ViFQRTWeybwamlVX3/gaAG3Y3BGKdLAXkZgXe8eqaVegepP85J29jfQXP+Ex4J4wW f5DRVj1uu46uhrK+91ibJ/Qoh/Wdl5h8A9e1yvx7KblfwGKSPN1p7FtD5DacL7bgsY bAAb76iuVq9v3SVtpYnL5fHylRspCQ0oV8ADQ30k=
Message-ID: <8ebc8e37878820424f70043045fe32c460fa39da.camel@nic.cz>
From: Ladislav Lhotka <lhotka@nic.cz>
To: Radek Krejčí <rkrejci@cesnet.cz>, Martin Bjorklund <mbj@tail-f.com>
Cc: FRANK RIMPLER <FRANK.RIMPLER@adtran.com>, YANG Doctors <yang-doctors@ietf.org>, netmod@ietf.org
Date: Fri, 13 Apr 2018 17:00:47 +0200
In-Reply-To: <abdcaa53-c5ce-4815-cf2b-904e6670e89e@cesnet.cz>
References: <f790c7e329684d78bec27a1bfe150d6c@EMEAWP-EXMB12.corp.brocade.com> <20160225.161659.2204602310947308417.mbj@tail-f.com> <cac18b6591244715b79376188fa4c3fe@EMEAWP-EXMB12.corp.brocade.com> <20160225.163105.511576225570588684.mbj@tail-f.com> <abdcaa53-c5ce-4815-cf2b-904e6670e89e@cesnet.cz>
Organization: CZ.NIC
Content-Type: text/plain; charset="UTF-8"
X-Mailer: Evolution 3.28.1
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
X-Virus-Scanned: clamav-milter 0.99.2 at mail
X-Virus-Status: Clean
Archived-At: <https://mailarchive.ietf.org/arch/msg/yang-doctors/MQHuxbkOpj6Prj_mkjlXSACJXsE>
Subject: Re: [yang-doctors] [netmod] Clarification needed for YANG 1.1 XPATH context
X-BeenThere: yang-doctors@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Email list of the yang-doctors directorate <yang-doctors.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/yang-doctors>, <mailto:yang-doctors-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/yang-doctors/>
List-Post: <mailto:yang-doctors@ietf.org>
List-Help: <mailto:yang-doctors-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/yang-doctors>, <mailto:yang-doctors-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 13 Apr 2018 15:00:53 -0000
On Fri, 2018-04-13 at 13:51 +0200, Radek Krejčí wrote: > Hi, > I'm refreshing an old thread to clarify specific use case, see below... > > Dne 25.2.2016 v 16:31 Martin Bjorklund napsal(a): > > William Ivory <wivory@Brocade.com> wrote: > > > > > > -----Original Message----- > > > From: Martin Bjorklund [mailto:mbj@tail-f.com] > > > Sent: 25 February 2016 15:17 > > > To: William Ivory <wivory@Brocade.com> > > > Cc: netmod@ietf.org > > > Subject: Re: [netmod] Clarification needed for YANG 1.1 XPATH context > > > > > > William Ivory <wivory@Brocade.com> wrote: > > > > Hi, > > > > > > > > I'm looking for clarification on the meaning of the following > > > > paragraph in section 6.4.1 (XPATH context) in RFC6020bis: > > > > > > > > 'If a node that exists in the accessible tree has a non-presence > > > > container as a child, then the non-presence container also exists in > > > > the tree.' > > > > > > > > It's unclear to me what this is trying to say, and why - for example, > > > > does this mean that I need to validate any 'must' and 'when' > > > > statements on the child container even when nothing within that child > > > > container is configured? > > > > > > must expressions are always evaluated if the node where the must > > > expression is defined exists, regardless of the number of children > > > this node has. > > > > > > [wivory] So in my example where the child container (non-presence) has > > > NO children, then it doesn't exist, and any must statement on it > > > should not be run. Only when a non-presence container has a non-zero > > > number of children should any 'must' statements on that container be > > > run. > > > > > > [wivory] If that's the case, then would it be correct to say that the > > > intention of this paragraph is as a reminder that one must evaluate > > > 'must' statements on nodes that have no inherent meaning and exist > > > only because they contain child nodes? > > > > No; section 7.5.3 says: > > > > When a datastore is validated, all "must" constraints are > > conceptually evaluated once for each node in the accessible tree (see > > Section 6.4.1). > > > > And the quoted paragraph of 6.4.1 says that the NP-container > > (conceptually) exists if its parent exists - regardless of number of > > children. > > > > So if the parent exists, any must expressions in the NP-container are > > evaluated. > > > > what about top-level NP-container with must constraint? Is a root node > something which is always present in accessible tree (even in an empty tree)? > Intuitively, I believe that it is, so even constraints on top-level NP- > containers are supposed to be evaluated, but I cannot find something about it > in RFC. Yes, this follows already from XPath 1.0 spec, section 5. Lada > > Regards, > Radek > > > _______________________________________________ > yang-doctors mailing list > yang-doctors@ietf.org > https://www.ietf.org/mailman/listinfo/yang-doctors -- Ladislav Lhotka Head, CZ.NIC Labs PGP Key ID: 0xB8F92B08A9F76C67
- Re: [yang-doctors] [netmod] Clarification needed … Radek Krejčí
- Re: [yang-doctors] [netmod] Clarification needed … Ladislav Lhotka