Re: [netconf] [core] YANG encoding in CBOR

Ladislav Lhotka <lhotka@nic.cz> Thu, 28 March 2019 09:33 UTC

Return-Path: <lhotka@nic.cz>
X-Original-To: netconf@ietfa.amsl.com
Delivered-To: netconf@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 46A32120165; Thu, 28 Mar 2019 02:33:20 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.899
X-Spam-Level:
X-Spam-Status: No, score=-1.899 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
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 KgNW019cq-e6; Thu, 28 Mar 2019 02:33:15 -0700 (PDT)
Received: from trail.lhotka.name (trail.lhotka.name [77.48.224.143]) by ietfa.amsl.com (Postfix) with ESMTP id C78141201A7; Thu, 28 Mar 2019 02:33:14 -0700 (PDT)
Received: by trail.lhotka.name (Postfix, from userid 109) id 2146118204C5; Thu, 28 Mar 2019 10:32:38 +0100 (CET)
Received: from localhost (nat-2.nic.cz [217.31.205.2]) by trail.lhotka.name (Postfix) with ESMTPSA id 29BEA1820047; Thu, 28 Mar 2019 10:32:31 +0100 (CET)
From: Ladislav Lhotka <lhotka@nic.cz>
To: Andy Bierman <andy@yumaworks.com>
Cc: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>, Michel Veillette <Michel.Veillette@trilliant.com>, "netconf\@ietf.org" <netconf@ietf.org>, "core\@ietf.org" <core@ietf.org>
In-Reply-To: <CABCOCHSm5LuqjSqvgxfXHKDai=76kKK=4mG=B+Dy9DEjaZpz0w@mail.gmail.com>
References: <6235c6683ff14848a661f8b8cec94280@XCH-RCD-007.cisco.com> <BL0PR06MB5042823429DB7CDA0F33408B9A430@BL0PR06MB5042.namprd06.prod.outlook.com> <588401AB-483E-40F5-95BB-20A066E56DAC@tzi.org> <15fbaf84b20343a1b83f40b571149a14@XCH-RCD-007.cisco.com> <1ADF8201-ABB4-44FD-A515-F3F8E0DBF5FC@tzi.org> <20190323101003.gp3zvsvqqwc26jip@anna.jacobs.jacobs-university.de> <871s2vqsxi.fsf@nic.cz> <BL0PR06MB5042C9AA6B4A0CCD913F50D89A580@BL0PR06MB5042.namprd06.prod.outlook.com> <20190327061637.g5a7t7nulk7kyh2v@anna.jacobs.jacobs-university.de> <1f8b326e0e05b400457b9446d52a7b0f6c90e05b.camel@nic.cz> <CABCOCHRKhvUzrDcELOWGHY5HWt7EQpq-iYdY84z3oqOCQjsATg@mail.gmail.com> <ce1bfc2916dcc3eadf03a46f901e08060c3858b2.camel@nic.cz> <CABCOCHSm5LuqjSqvgxfXHKDai=76kKK=4mG=B+Dy9DEjaZpz0w@mail.gmail.com>
Date: Thu, 28 Mar 2019 10:33:06 +0100
Message-ID: <87r2armjhp.fsf@nic.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://mailarchive.ietf.org/arch/msg/netconf/ToSTOFVP0Yz_bY7ApnsFpeKbBPE>
Subject: Re: [netconf] [core] YANG encoding in CBOR
X-BeenThere: netconf@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: NETCONF WG list <netconf.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/netconf>, <mailto:netconf-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/netconf/>
List-Post: <mailto:netconf@ietf.org>
List-Help: <mailto:netconf-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/netconf>, <mailto:netconf-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 28 Mar 2019 09:33:20 -0000

Andy Bierman <andy@yumaworks.com>; writes:

> On Wed, Mar 27, 2019 at 12:54 PM Ladislav Lhotka <lhotka@nic.cz>; wrote:
>
>> Andy Bierman píše v St 27. 03. 2019 v 09:13 -0700:
>> >
>> >
>> > On Wed, Mar 27, 2019 at 1:40 AM Ladislav Lhotka <lhotka@nic.cz>; wrote:
>> > > On Wed, 2019-03-27 at 07:16 +0100, Juergen Schoenwaelder wrote:
>> > > > Hi,
>> > > >
>> > > > a union can be formed by using member types that are imported and not
>> > > > under change control of a single author/organization and ideally this
>> > > > should work without complex coordination of name and number spaces.
>> > > > Duplicate enum/bits values are legal in YANG today so an encoding has
>> > > > to deal with this aspect of life.
>> > > >
>> > > > A robust fix to all these problems will be to tag the type members in
>> > > > order to discriminate the values in the encodings. This, however,
>> will
>> > > > take some time to specify and we will need to preserve backwards
>> > > > compatibility with unions without a tag (but compilers can encourage
>> > > > people to add tags whenever modules are updated).
>> > >
>> > > I already opened a new issue for this in yang-next:
>> > >
>> > > https://github.com/netmod-wg/yang-next/issues/72
>> > >
>> >
>> > We already explored the solution of giving the member types numbers
>> > so they could be used in CBOR but this was rejected because it is so
>> complex
>> > to implement.
>>
>> I don't think it is too complex. Get the type in the schema, get the
>> member,
>> that's all. It is much easier and more robust than the current algorithm.
>>
>>
> no it isn't easier because the algorithm is error-prone.
> Renumbering un-named types nested within unions and referenced named types
> over many revisions of the module is not easy.
> The encoding MUST NOT change EVER -- even if the union type is expanded.
>
>
>> >
>> > Consider when union is within union, and the types are named types from
>>
>> Union within union is no problem: it jut requires a sequence of numbers.
>>
>>
> do not agree since the union can have a member type added
>
>
>
>> > other modules. Union types can be legally updated in new versions of the
>> > module,
>>
>> Again, I don't agree. Sec. 11 in RFC 7950 says:
>>
>>    o  A "type" statement may be replaced with another "type" statement
>>       that does not change the syntax or semantics of the type.
>>       ...
>>
>>
>
>    type uint32 { range "1..8"; }
>
> I can refactor that into 2 types (1..4 and 5..8)

This looks like a pretty contrived example, why would somebody want to
do this?

Anyway, regarding updates: one can have this union

type union {
  type uint32 {
    range "1..3";
  }
  type string;
}

So, in XML representation, the value of 4 will be classified as
a string. Now, according to sec. 11, it is legal to expand the range to
1..10, say. Suddenly, the same value becomes a number.

> This does not change the semantics of the union type but it adds a member
> type
> Other refactoring is possible that will also change the number of member
> types.
>
> Also, deviations do not follow this rule
>
>
>
>> Adding a new member clearly changes the semantics of the type, if not
>> syntax.
>>
>>
> no it doesn't always change the semantics
>
>
>
>> > but the position assignments for SID can never change.
>>
>> The annotation would also help resolve the differences between JSON and
>> XML. SID
>> is only available in CBOR.
>>
>> >
>> > Even without this complexity this solution would cause the
>> encoder/decoder to
>> > be very schema-aware.
>>
>> The current method of resolving unions is totally schema-aware (somewhat
>> less so
>> in JSON).
>>
>>
> No -- it just needs to know string vs. number.
> Not schema aware at all.

Of course it is. With both strings and numbers, you also have to check
restrictions if they are specified in the schema (pattern, range etc.),
deref leafrefs etc.

I think we all agree that unions in YANG are fragile and may cause
subtle problems. If a better solution is found, then fine, but IMO it
needs to be addressed, and not only in CBOR.

Lada

>
>
>> Lada
>>
>>
> Andy
>
>
>> >
>> >
>> > BTW, creating SIDs for enums and bits will break if the server uses
>> 'deviate
>> > replace type'.
>> > There is no way to number the deviated type since this is
>> server-specific not
>> > part of the original module
>> > and the deviation is not actually a data-def-stmt.
>> >
>> >
>> > > Lada
>> > >
>> >
>> > Andy
>> >
>> > > >
>> > > > /js
>> > > >
>> > > > On Wed, Mar 27, 2019 at 01:12:52AM +0000, Michel Veillette wrote:
>> > > > > Hi Ladislav
>> > > > >
>> > > > > If I summarize this issue of multiple enumerations or bits in a
>> union,
>> > > this
>> > > > > problem can be solve by the following approaches:
>> > > > >
>> > > > > - To not allows these duplicate values or positions to happen in
>> YANG
>> > > > > - To encode enumerations and bits as string (in all unions or only
>> when
>> > > > > multiple enumerations or bits are defined)
>> > > > > - To encode enumerations and bits as SID (in all unions or only
>> when
>> > > > > multiple enumerations or bits are defined)
>> > > > > - To encode enumerations and bits as delta between the value SID
>> and the
>> > > > > leaf SID (in all unions or only when multiple enumerations or bits
>> are
>> > > > > defined)
>> > > > >
>> > > > > In this email, I will like to focus on the first option, fixing the
>> > > problem
>> > > > > directly in YANG instead of fixing the consequences.
>> > > > >
>> > > > > Without any changes in YANG, a union with multiple enumeration or
>> bits
>> > > can
>> > > > > be constructed without value or position overlaps.
>> > > > > For example:
>> > > > >
>> > > > >   leaf multiple-enumerations-test-1 {
>> > > > >     type union {
>> > > > >       type enumeration {
>> > > > >         enum "Monday" { value 0; }
>> > > > >         enum "Tuesday" { value 1; }
>> > > > >         enum "Wednesday" { value 2; }
>> > > > >         enum "Thursday" { value 3; }
>> > > > >         enum "Friday" { value 4; }
>> > > > >
>> > > > >       }
>> > > > >       type enumeration {
>> > > > >         enum "Saturday" { value 5; }
>> > > > >         enum "Sunday" { value 6; }
>> > > > >       }
>> > > > >     }
>> > > > >   }
>> > > > >
>> > > > >   leaf multiple-bits-test-1 {
>> > > > >     type union {
>> > > > >       type bits {
>> > > > >         bit  "Monday" { position  0; }
>> > > > >         bit "Tuesday" { position  1; }
>> > > > >         bit "Wednesday" { position  2; }
>> > > > >         bit "Thursday" { position  3; }
>> > > > >         bit "Friday" { position  4; }
>> > > > >
>> > > > >       }
>> > > > >       type bits {
>> > > > >         bit "Saturday" { position 5; }
>> > > > >         bit "Sunday" { position 6; }
>> > > > >       }
>> > > > >     }
>> > > > >   }
>> > > > >
>> > > > > When using already defined typedef, avoiding overlap is less
>> obvious
>> > > without
>> > > > > some help.
>> > > > > To help building unions with already defined typedefs, I propose to
>> > > > > introduce two extensions.
>> > > > >
>> > > > >   extension value-offset {
>> > > > >     argument offset {
>> > > > >       yin-element true;
>> > > > >     }
>> > > > >     description
>> > > > >       "Offset added to each enum value of the associated
>> enumeration.";
>> > > > >   }
>> > > > >
>> > > > >   extension position-offset {
>> > > > >     argument offset {
>> > > > >       yin-element true;
>> > > > >     }
>> > > > >     description
>> > > > >       "Offset value added to each bit position of the associated
>> bits.";
>> > > > >   }
>> > > > >
>> > > > > The value-offset extension can be used as follow:
>> > > > >
>> > > > >     type enumeration {
>> > > > >       enum "Monday";
>> > > > >       enum "Tuesday";
>> > > > >       enum "Wednesday";
>> > > > >       enum "Thursday";
>> > > > >       enum "Friday";
>> > > > >     }
>> > > > >   }
>> > > > >
>> > > > >   typedef weekend {
>> > > > >     type enumeration {
>> > > > >       enum "Saturday";
>> > > > >       enum "Sunday";
>> > > > >     }
>> > > > >   }
>> > > > >
>> > > > >   leaf multiple-enumerations-test-3 {
>> > > > >     type union {
>> > > > >       type weekdays;
>> > > > >       type weekend {
>> > > > >         ext:value-offset 5;
>> > > > >       }
>> > > > >     }
>> > > > >   }
>> > > > >
>> > > > > The position-offset extension can be used as follow:
>> > > > >
>> > > > >   typedef weekdays-flags {
>> > > > >     type bits {
>> > > > >       bit "Monday";
>> > > > >       bit "Tuesday";
>> > > > >       bit "Wednesday";
>> > > > >       bit "Thursday";
>> > > > >       bit "Friday";
>> > > > >     }
>> > > > >   }
>> > > > >
>> > > > >   typedef weekend-flags {
>> > > > >     type bits {
>> > > > >       bit "Saturday";
>> > > > >       bit "Sunday";
>> > > > >     }
>> > > > >   }
>> > > > >
>> > > > >   leaf multiple-bits-test-3 {
>> > > > >     type union {
>> > > > >       type weekdays-flags;
>> > > > >       type weekend-flags {
>> > > > >         ext:position-offset 5;
>> > > > >       }
>> > > > >     }
>> > > > >   }
>> > > > >
>> > > > > The yang file in attachment show different examples based on this
>> > > approach.
>> > > > > This module have been validated using
>> > > http://www.yangvalidator.com/validator
>> > > > >
>> > > > > If this approach is accepted, tools like pyang should be updated to
>> > > produce
>> > > > > an error if multiple enumerations or bits are defined with value or
>> > > position
>> > > > > overleaps.
>> > > > >
>> > > > > Please comment,
>> > > > > Michel
>> > > > >
>> > > > > -----Original Message-----
>> > > > > From: Ladislav Lhotka <lhotka@nic.cz>;
>> > > > > Sent: Monday, March 25, 2019 4:07 AM
>> > > > > To: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>;;
>> > > Carsten
>> > > > > Bormann <cabo@tzi.org>;
>> > > > > Cc: Michel Veillette <Michel.Veillette@trilliant.com>;;
>> netconf@ietf.org;
>> > >
>> > > > > core@ietf.org
>> > > > > Subject: Re: [netconf] YANG encoding in CBOR
>> > > > >
>> > > > > Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>;
>> writes:
>> > > > >
>> > > > > > I think we need to look at the whole picture and in which
>> direction
>> > > we
>> > > > > > want to go. In the longer term, I would prefer a solution where
>> the
>> > > > > > values of a union are discriminated. The current XML encoding
>> > > > > > behaviour of 'first match wins' is fragile (for example, if
>> someone
>> > > > > > adds an enum to a type, the interpretation of data can change).
>> > > > > >
>> > > > > > Look at this:
>> > > > > >
>> > > > > > typedef bar {
>> > > > > >   type union {
>> > > > > >     type enumeration { enum "1"; value 2; enum "2"; value 1; }
>> > > > > >     type uint8;
>> > > > > >   }
>> > > > > > }
>> > > > > >
>> > > > > > We have some encodings that send the string representations of
>> the
>> > > > > > values and some encodings that prefer to send numeric
>> representations
>> > > > > > where possible. In order to have a robust solution, encodings
>> should
>> > > > > > likely indicate to which type the value belongs.
>> > > > >
>> > > > > Perhaps the easiest way would be to use (optional) annotation that
>> > > > > specifies, using an ordinal number, which of the member types is
>> used
>> > > for
>> > > > > the particular instance. But since there can be unions inside
>> unions, a
>> > > list
>> > > > > of numbers would be needed in general.
>> > > > >
>> > > > > Lada
>> > > > >
>> > > > > > /js
>> > > > > >
>> > > > > > On Sat, Mar 23, 2019 at 10:03:32AM +0100, Carsten Bormann wrote:
>> > > > > > > Well, if that is a problem, we can go for a longer
>> representation
>> > > within
>> > > > > > > unions (section 6.12).  Theoretically, we could do that only of
>> > > there is
>> > > > > > > more than one enum in the union type (so things stay efficient
>> if
>> > > there
>> > > > > > > is only one), but that might pose difficulties with model
>> evolution.
>> > > > > > >
>> > > > > > > Going for a string representation repeats the feature of XML
>> YANG
>> > > (which
>> > > > > > > was ported over to JSON YANG):
>> > > > > > >
>> > > > > > > typedef foo {
>> > > > > > >   type union {
>> > > > > > >     type enumeration {
>> > > > > > >       enum red { value 1; }
>> > > > > > >       enum breen { value 2; }
>> > > > > > >       enum glue { value 3; }
>> > > > > > >     }
>> > > > > > >     type enumeration {
>> > > > > > >       enum tacks { value 1; }
>> > > > > > >       enum nails { value 2; }
>> > > > > > >       enum glue { value 3; }
>> > > > > > >     }
>> > > > > > >   }
>> > > > > > > }
>> > > > > > >
>> > > > > > > If you use “glue”, you don’t know which of the enumerations are
>> > > being
>> > > > > > > used.
>> > > > > > >
>> > > > > > > Using SIDs, we can do better.
>> > > > > > >
>> > > > > > > So what do we have to do to get the SID tool to allocate SIDs
>> for
>> > > enum
>> > > > > > > values?
>> > > > > > >
>> > > > > > > We could then define the CBOR tag for enums in unions to take
>> the
>> > > usual
>> > > > > > > SID difference (delta relative to the environment, I’d think),
>> not
>> > > an
>> > > > > > > integer value.
>> > > > > > >
>> > > > > > > Several of us are at the hackathon and could make something
>> happen
>> > > today
>> > > > > > > and tomorrow.
>> > > > > > >
>> > > > > > > Grüße, Carsten
>> > > > > > >
>> > > > > > >
>> > > > > > > > On Mar 22, 2019, at 18:30, Rob Wilton (rwilton) <
>> rwilton@cisco.com
>> > > >
>> > > > > > > > wrote:
>> > > > > > > >
>> > > > > > > > I guess that the concern is that this introduces more
>> variation in
>> > > how
>> > > > > > > > data is interpreted between the different XML/JSON/CBOR
>> encodings.
>> > > > > > > >
>> > > > > > > > E.g. if someone switched from XML to CBOR, suddenly the
>> > > configuration
>> > > > > > > > or state data may have a different meaning.
>> > > > > > > >
>> > > > > > > > Thanks,
>> > > > > > > > Rob
>> > > > > > > >
>> > > > > > > >
>> > > > > > > > > -----Original Message-----
>> > > > > > > > > From: Carsten Bormann <cabo@tzi.org>;
>> > > > > > > > > Sent: 22 March 2019 16:08
>> > > > > > > > > To: Michel Veillette <Michel.Veillette@trilliant.com>;
>> > > > > > > > > Cc: Rob Wilton (rwilton) <rwilton@cisco.com>;;
>> core@ietf.org;
>> > > > > > > > > netconf@ietf.org
>> > > > > > > > > Subject: Re: [netconf] YANG encoding in CBOR
>> > > > > > > > >
>> > > > > > > > > On Mar 22, 2019, at 16:45, Michel Veillette
>> > > > > > > > > <Michel.Veillette@trilliant.com>;
>> > > > > > > > > wrote:
>> > > > > > > > > > The only potential problem I aware is when multiple
>> > > enumerations
>> > > > > > > > > > are part of
>> > > > > > > > > the same union.
>> > > > > > > > > > Value 4 from enumeration A will be encoded the same way
>> as
>> > > Value
>> > > > > > > > > > 4 from
>> > > > > > > > > enumeration B.
>> > > > > > > > >
>> > > > > > > > > … and that is not a problem for the XML version, because
>> the
>> > > > > > > > > string is being used instead of the value.  (But then if
>> two
>> > > > > > > > > enumerations share a string, you have the equivalent
>> problem in
>> > > > > > > > > the XML serialization.)
>> > > > > > > > >
>> > > > > > > > > Anyway, I haven’t seen a piece of real-world YANG that
>> actually
>> > > > > > > > > has this problem, so I would be a bit reluctant to make
>> CBOR-
>> > > based
>> > > > > > > > > implementations more complex (and less efficient) so solve
>> this
>> > > > > > > > > (non-?)problem.
>> > > > > > > > >
>> > > > > > > > > Grüße, Carsten
>> > > > > > > >
>> > > > > > > >
>> > > > > > >
>> > > > > > > _______________________________________________
>> > > > > > > netconf mailing list
>> > > > > > > netconf@ietf.org
>> > > > > > >
>> > > https://can01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww
>> > > > > > >
>> > > .ietf.org%2Fmailman%2Flistinfo%2Fnetconf&amp;data=02%7C01%7C%7C343ea8
>> > > > > > >
>> > > d1cf8f4e39afc708d6b0f8d874%7C4f6fbd130dfb415085c3d43260c04309%7C0%7C1
>> > > > > > >
>> > > %7C636890980182553400&amp;sdata=u1KFAYAus16B8a7sgsBfPfIquOptMlaOb%2B0
>> > > > > > > kvPZgr4o%3D&amp;reserved=0
>> > > > > >
>> > > > > > --
>> > > > > > Juergen Schoenwaelder           Jacobs University Bremen gGmbH
>> > > > > > Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen |
>> Germany
>> > > > > > Fax:   +49 421 200 3103         <
>> > > > > >
>> > >
>> https://can01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jacobs-university.de%2F&amp;data=02%7C01%7C%7C343ea8d1cf8f4e39afc708d6b0f8d874%7C4f6fbd130dfb415085c3d43260c04309%7C0%7C1%7C636890980182553400&amp;sdata=TrW2iL3nUDlZ%2BVvhPxWeqdU1X%2BqvFCnXyodX6Bu1e94%3D&amp;reserved=0
>> > > > > > >
>> > > > > >
>> > > > > >
>> > > > > > On Sat, Mar 23, 2019 at 10:03:32AM +0100, Carsten Bormann wrote:
>> > > > > > > Well, if that is a problem, we can go for a longer
>> representation
>> > > within
>> > > > > > > unions (section 6.12).  Theoretically, we could do that only of
>> > > there is
>> > > > > > > more than one enum in the union type (so things stay efficient
>> if
>> > > there
>> > > > > > > is only one), but that might pose difficulties with model
>> evolution.
>> > > > > > >
>> > > > > > > Going for a string representation repeats the feature of XML
>> YANG
>> > > (which
>> > > > > > > was ported over to JSON YANG):
>> > > > > > >
>> > > > > > > typedef foo {
>> > > > > > >   type union {
>> > > > > > >     type enumeration {
>> > > > > > >       enum red { value 1; }
>> > > > > > >       enum breen { value 2; }
>> > > > > > >       enum glue { value 3; }
>> > > > > > >     }
>> > > > > > >     type enumeration {
>> > > > > > >       enum tacks { value 1; }
>> > > > > > >       enum nails { value 2; }
>> > > > > > >       enum glue { value 3; }
>> > > > > > >     }
>> > > > > > >   }
>> > > > > > > }
>> > > > > > >
>> > > > > > > If you use “glue”, you don’t know which of the enumerations are
>> > > being
>> > > > > > > used.
>> > > > > > >
>> > > > > > > Using SIDs, we can do better.
>> > > > > > >
>> > > > > > > So what do we have to do to get the SID tool to allocate SIDs
>> for
>> > > enum
>> > > > > > > values?
>> > > > > > >
>> > > > > > > We could then define the CBOR tag for enums in unions to take
>> the
>> > > usual
>> > > > > > > SID difference (delta relative to the environment, I’d think),
>> not
>> > > an
>> > > > > > > integer value.
>> > > > > > >
>> > > > > > > Several of us are at the hackathon and could make something
>> happen
>> > > today
>> > > > > > > and tomorrow.
>> > > > > > >
>> > > > > > > Grüße, Carsten
>> > > > > > >
>> > > > > > >
>> > > > > > > > On Mar 22, 2019, at 18:30, Rob Wilton (rwilton) <
>> rwilton@cisco.com
>> > > >
>> > > > > > > > wrote:
>> > > > > > > >
>> > > > > > > > I guess that the concern is that this introduces more
>> variation in
>> > > how
>> > > > > > > > data is interpreted between the different XML/JSON/CBOR
>> encodings.
>> > > > > > > >
>> > > > > > > > E.g. if someone switched from XML to CBOR, suddenly the
>> > > configuration
>> > > > > > > > or state data may have a different meaning.
>> > > > > > > >
>> > > > > > > > Thanks,
>> > > > > > > > Rob
>> > > > > > > >
>> > > > > > > >
>> > > > > > > > > -----Original Message-----
>> > > > > > > > > From: Carsten Bormann <cabo@tzi.org>;
>> > > > > > > > > Sent: 22 March 2019 16:08
>> > > > > > > > > To: Michel Veillette <Michel.Veillette@trilliant.com>;
>> > > > > > > > > Cc: Rob Wilton (rwilton) <rwilton@cisco.com>;;
>> core@ietf.org;
>> > > > > > > > > netconf@ietf.org
>> > > > > > > > > Subject: Re: [netconf] YANG encoding in CBOR
>> > > > > > > > >
>> > > > > > > > > On Mar 22, 2019, at 16:45, Michel Veillette
>> > > > > > > > > <Michel.Veillette@trilliant.com>;
>> > > > > > > > > wrote:
>> > > > > > > > > > The only potential problem I aware is when multiple
>> > > enumerations
>> > > > > > > > > > are part of
>> > > > > > > > > the same union.
>> > > > > > > > > > Value 4 from enumeration A will be encoded the same way
>> as
>> > > Value
>> > > > > > > > > > 4 from
>> > > > > > > > > enumeration B.
>> > > > > > > > >
>> > > > > > > > > … and that is not a problem for the XML version, because
>> the
>> > > > > > > > > string is being used instead of the value.  (But then if
>> two
>> > > > > > > > > enumerations share a string, you have the equivalent
>> problem in
>> > > > > > > > > the XML serialization.)
>> > > > > > > > >
>> > > > > > > > > Anyway, I haven’t seen a piece of real-world YANG that
>> actually
>> > > > > > > > > has this problem, so I would be a bit reluctant to make
>> CBOR-
>> > > based
>> > > > > > > > > implementations more complex (and less efficient) so solve
>> this
>> > > > > > > > > (non-?)problem.
>> > > > > > > > >
>> > > > > > > > > Grüße, Carsten
>> > > > > > > >
>> > > > > > > >
>> > > > > > >
>> > > > > > > _______________________________________________
>> > > > > > > netconf mailing list
>> > > > > > > netconf@ietf.org
>> > > > > > >
>> > > https://can01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww
>> > > > > > >
>> > > .ietf.org%2Fmailman%2Flistinfo%2Fnetconf&amp;data=02%7C01%7C%7C343ea8
>> > > > > > >
>> > > d1cf8f4e39afc708d6b0f8d874%7C4f6fbd130dfb415085c3d43260c04309%7C0%7C1
>> > > > > > >
>> > > %7C636890980182553400&amp;sdata=u1KFAYAus16B8a7sgsBfPfIquOptMlaOb%2B0
>> > > > > > > kvPZgr4o%3D&amp;reserved=0
>> > > > > >
>> > > > > > --
>> > > > > > Juergen Schoenwaelder           Jacobs University Bremen gGmbH
>> > > > > > Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen |
>> Germany
>> > > > > > Fax:   +49 421 200 3103         <
>> > > > > >
>> > >
>> https://can01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jacobs-university.de%2F&amp;data=02%7C01%7C%7C343ea8d1cf8f4e39afc708d6b0f8d874%7C4f6fbd130dfb415085c3d43260c04309%7C0%7C1%7C636890980182553400&amp;sdata=TrW2iL3nUDlZ%2BVvhPxWeqdU1X%2BqvFCnXyodX6Bu1e94%3D&amp;reserved=0
>> > > > > > >
>> > > > > >
>> > > > > > _______________________________________________
>> > > > > > netconf mailing list
>> > > > > > netconf@ietf.org
>> > > > > >
>> https://can01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.
>> > > > > > ietf.org
>> %2Fmailman%2Flistinfo%2Fnetconf&amp;data=02%7C01%7C%7C343ea8d1
>> > > > > >
>> cf8f4e39afc708d6b0f8d874%7C4f6fbd130dfb415085c3d43260c04309%7C0%7C1%7C
>> > > > > >
>> 636890980182553400&amp;sdata=u1KFAYAus16B8a7sgsBfPfIquOptMlaOb%2B0kvPZ
>> > > > > > gr4o%3D&amp;reserved=0
>> > > > >
>> > > > > --
>> > > > > Ladislav Lhotka
>> > > > > Head, CZ.NIC Labs
>> > > > > PGP Key ID: 0xB8F92B08A9F76C67
>> > > >
>> > > >
>> --
>> Ladislav Lhotka
>> Head, CZ.NIC Labs
>> PGP Key ID: 0xB8F92B08A9F76C67
>>
>>

-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67