Re: [ldapext] DBIS commentary

Steven Legg <steven.legg@viewds.com> Fri, 27 November 2015 05:40 UTC

Return-Path: <steven.legg@viewds.com>
X-Original-To: ldapext@ietfa.amsl.com
Delivered-To: ldapext@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 024A01AC447 for <ldapext@ietfa.amsl.com>; Thu, 26 Nov 2015 21:40:16 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.901
X-Spam-Level:
X-Spam-Status: No, score=-1.901 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, SPF_PASS=-0.001] autolearn=ham
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 RDHcsC-NOOEZ for <ldapext@ietfa.amsl.com>; Thu, 26 Nov 2015 21:40:13 -0800 (PST)
Received: from mail-pa0-x235.google.com (mail-pa0-x235.google.com [IPv6:2607:f8b0:400e:c03::235]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 922741AC446 for <ldapext@ietf.org>; Thu, 26 Nov 2015 21:40:13 -0800 (PST)
Received: by padhx2 with SMTP id hx2so104492145pad.1 for <ldapext@ietf.org>; Thu, 26 Nov 2015 21:40:13 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=viewds-com.20150623.gappssmtp.com; s=20150623; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-type:content-transfer-encoding; bh=G+BmLtkddmZxHa7sRSlEuBPmAzh6sFV98jwUankS+RQ=; b=pQTwMta1Ljo+FQDjdbDEAMky1ptq1rm4w0s4DexNW8Jh4KIOlY3JSKiQcNvaMIXKEU Pdf6BmFLRou+h3VjPjY9wq95R/SD8eIAC98sRlhPbLnfpvV8zhJ+He1xowi11s/xVLUJ E/2kJ0/qzP48dz46Xf979Vx7vOTzvMdbA9d4G+x4M6tUloDWtTGVMeIf84b7Kjmh1lAN t53YogJU3LuXRE+D1juBRfADZQBLi3AW4d+34tnR0fGXwzwxgII9FV+PrWokUU8c+D1Q /RiyQsYHoK9ptXgUBtMMLmuN6mTUshrvwI9C2ufFAFSvEUO+jCI0WBPgj/XpEhQ72XPt QjpQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-type :content-transfer-encoding; bh=G+BmLtkddmZxHa7sRSlEuBPmAzh6sFV98jwUankS+RQ=; b=QM0d0vxyK0MYwBfghRSEPuFzijPRg1FwaZ/Ysxrrd2YTCHuPPHcwNCodyKnnLDeJYv ZQX40M4jLE7z4DGEACZaB06ucqaDZyG+JYgwz/CyilyhdMeMpMOktDRYzMMXaSlQkdUA PHpif50qrPdaF2l7eNLrdeg6vnqtcAJHMVXqYaX7py6lgPMPzQTj7z4wYZJ3CXk/EcLF rKX4LxnNXb0yE9nN3DpQMrV1hxKpXWZ2IsXYH2D+1D14ujAdyXLAxlRuSnvr2Yi9pAU9 Bg/kYWrWeDEIF9TkRxWZfeC7lf/KLml/aWTYFaauCRjY1tMdLRD2E7m1KZYE+1xKEvsp LlRw==
X-Gm-Message-State: ALoCoQlZyB28UCFF9dz7UFDEOaYgqMPkkHgdW/GZy1ZqrtzZPEkHTN8vTqKSjTHRXUhbOY0fUgG1
X-Received: by 10.98.86.92 with SMTP id k89mr45337911pfb.111.1448602813247; Thu, 26 Nov 2015 21:40:13 -0800 (PST)
Received: from [192.168.1.1] (202.164.192.219.static.rev.eftel.com. [202.164.192.219]) by smtp.googlemail.com with ESMTPSA id v64sm30987688pfi.50.2015.11.26.21.40.10 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 26 Nov 2015 21:40:12 -0800 (PST)
To: "Bannister, Mark" <Mark.Bannister@morganstanley.com>, 'Jordan Brown' <Jordan.Brown@oracle.com>
References: <5655E4F0.7030809@oracle.com> <814F4E458AA9FF4E89CF1A9EDA0DE2A932F618A3@OZWEX0209N1.msad.ms.com>
From: Steven Legg <steven.legg@viewds.com>
Message-ID: <5657ECB8.1010601@viewds.com>
Date: Fri, 27 Nov 2015 16:40:08 +1100
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0
MIME-Version: 1.0
In-Reply-To: <814F4E458AA9FF4E89CF1A9EDA0DE2A932F618A3@OZWEX0209N1.msad.ms.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Archived-At: <http://mailarchive.ietf.org/arch/msg/ldapext/2OKymMTXgqIH8dD5HQLzR-PqQBU>
Cc: "'ldapext@ietf.org'" <ldapext@ietf.org>
Subject: Re: [ldapext] DBIS commentary
X-BeenThere: ldapext@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: LDAP Extension Working Group <ldapext.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ldapext>, <mailto:ldapext-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ldapext/>
List-Post: <mailto:ldapext@ietf.org>
List-Help: <mailto:ldapext-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ldapext>, <mailto:ldapext-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 27 Nov 2015 05:40:16 -0000

Hi Mark & Jordan,

On 26/11/2015 10:01 PM, Bannister, Mark wrote:
[snip]

>> Footnote 1 says that published classes may not be redefined. Although not all changes seem permissible,
>> some changes (e.g. addition of MAY elements) seem like they could be allowed.  Is there a reference for
>> this restriction?  Note that between X.521-1993 and X.521-2012 the TelecommunicationAttributeSet had
>> an attribute deleted.
>
> I haven't looked for a reference to this restriction, I had learned it from seeing previous exchanges
> on the ldapext mailing list with Kurt Zeilenga.  Here is one such exchange, regarding changing the
> schema declaration of 'posixGroup' in RFC2307bis:
>
> https://www.ietf.org/mail-archive/web/ldapext/current/msg02072.html

The rules of extensibility for object classes in X.519-2008, Clause 12.4 say:

     "Optional user attributes may be added to an existing object class without
      assigning a new object identifier."

Removing an attribute isn't covered, so by omission, it isn't allowed.

I don't recall the LDAP specifications having anything specific to say on the
matter, though I suspect the prevailing attitude is that you can't change an
object class without changing the OID.

The teletexTerminalIdentifier attribute was removed from TelecommunicationAttributeSet
because the service and/or the specifications were defunct, but it was a violation
of X.500's own extensibility rules. IMO the attribute should have just been made
obsolete. To get around possible interoperability problems I treat the new object
class definitions minus teletexTerminalIdentifier as the "original" definitions so
if I encounter a definition that includes teletexTerminalIdentifier it looks like
an allowed extension to the object class.

[snip]

Regards,
Steven