[netmod] enable features to be supported per grouping-use (not globally per-datastore)

Kent Watsen <kent+ietf@watsen.net> Fri, 26 April 2019 16:06 UTC

Return-Path: <0100016a5a6621e0-e6c8c625-251c-4611-b5a9-fe24c5340cc2-000000@amazonses.watsen.net>
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 A33AE120220 for <netmod@ietfa.amsl.com>; Fri, 26 Apr 2019 09:06:46 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.9
X-Spam-Level:
X-Spam-Status: No, score=-1.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=amazonses.com
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 A0eZMWBrH8hL for <netmod@ietfa.amsl.com>; Fri, 26 Apr 2019 09:06:45 -0700 (PDT)
Received: from a8-64.smtp-out.amazonses.com (a8-64.smtp-out.amazonses.com [54.240.8.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 60140120203 for <netmod@ietf.org>; Fri, 26 Apr 2019 09:06:45 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=6gbrjpgwjskckoa6a5zn6fwqkn67xbtw; d=amazonses.com; t=1556294804; h=From:Content-Type:Content-Transfer-Encoding:Mime-Version:Subject:Message-Id:Date:To:Feedback-ID; bh=23CeRxxpIAFdROerNjdNSjs1334pBnkXLgRCa5R1SOY=; b=lkEAgzRReS8a5tkEoSDDLGizDP6DqiGQk+qZ4vw0m68wFUY8fG9nyYx8E++FbTwg wSm2+twVmfRqu8congdsPkNTP7LrShhfBNTe+zlokzM5jpt5fLiGIv7bLZEa5ZZuhjT P1o/ybXuayl4pKORLPrxdL4KE/NIS7WkW9R0rbYk=
From: Kent Watsen <kent+ietf@watsen.net>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Mime-Version: 1.0 (Mac OS X Mail 12.2 \(3445.102.3\))
Message-ID: <0100016a5a6621e0-e6c8c625-251c-4611-b5a9-fe24c5340cc2-000000@email.amazonses.com>
Date: Fri, 26 Apr 2019 16:06:44 +0000
To: "netmod@ietf.org" <netmod@ietf.org>
X-Mailer: Apple Mail (2.3445.102.3)
X-SES-Outgoing: 2019.04.26-54.240.8.64
Feedback-ID: 1.us-east-1.DKmIRZFhhsBhtmFMNikgwZUWVrODEw9qVcPhqJEI2DA=:AmazonSES
Archived-At: <https://mailarchive.ietf.org/arch/msg/netmod/XNgLlHcplYKaWfcCAniGraNocCc>
Subject: [netmod] enable features to be supported per grouping-use (not globally per-datastore)
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: Fri, 26 Apr 2019 16:06:47 -0000

Use case:

  - a shared low-level module defines a feature and 
    defines a grouping with an if-feature with it.
  - the grouping is used by various higher-level modules.
  - in some uses of the grouping, the feature is desired,
    and in others not.
  - current yang-library enables the feature globally 
    (per-datastore), which prevents local variations

Possible workaround:

  - each higher-level module can redeclare the feature
    and augment in its own if-feature statements.
  - this seems heavy and probably doesn't scale well.
  - e.g., servers would support all the low-level
    features (or perhaps the subset needed via some
    cascading dependency tree), and then selectively
    support the higher-level features.

Thoughts?

Kent // contributor