Subject: [NGO] A proposed WG Charter for NETMOD: NETCONF Data Modeling

From: David Partain <[email-masked]>
Date: Mon, 31 Mar 2008 21:30:34 +0200

Greetings,

Since the last IETF, a group of people has been working on
creating a charter proposal for work in new working group as a
result of the many discussions, BoFs, semi-BoFs, bar BoFs...  on
a modeling language for NETCONF.  We did this at the request of
our O&M ADs.

The group included Alex Clemm, Balázs Lengyel, Bernd Linowski,
Bert Wijnen, David Harrington, David Partain, Jung Tjong,
Ladislav Lhotka, Martin Björklund, Martin Storch, Mehmet Ersue,
Phil Shafer, Randy Presuhn, Rohan Mahy, and Sharon Chisholm.

We've worked very hard on this (LOTS of email), and, while we don't all agree 
on every word, I believe we're all in agreement on the general direction 
forward.

Our proposal is below and we look forward to your comments here on NGO.

With kind regards,

David Partain

---------------------------------------------------------------
NETMOD: NETCONF Data Modeling

Chairs: TBD

The NETCONF Working Group has completed a base protocol to be
used for configuration management.  However, the NETCONF protocol
does not include a standard content layer.  The specifications do
not include a modeling language or accompanying rules that can be
used to model the management information that is to be configured
using NETCONF. This has resulted in inconsistent syntax and
interoperability problems. The purpose of NETMOD is to support
the ongoing development of IETF and vendor-defined data models
for NETCONF.

NETMOD's requirements are drawn from the RCDML requirements draft
(draft-presuhn-rcdml) and documents referenced therein.

The WG will define a "human-friendly" modeling language defining
the semantics of operational data, configuration data,
notifications, and operations.  This language will focus on
readability and ease of use.  This language must be able to serve
as the normative description of NETCONF data models.  The WG will
use YANG (draft-bjorklund-yang) as its starting point for this
language.

Language abstractions that facilitate model extensibility and
reuse have been identified as a work area and will be considered
as a work item or may be integrated into the YANG document based
on WG consensus.

The WG will define a canonical mapping of this language to
NETCONF XML instance documents, the on-the-wire format of
YANG-defined XML content.  Only data models defined in YANG will
have to adhere to this on-the-wire format.

In order to leverage existing XML tools for validating NETCONF
data in various contexts and also facilitate exchange of data
models and schemas with other IETF working groups, the WG will
define standard mappings from YANG to the DSDL data modeling
framework (ISO/IEC 19757) with additional annotations to preserve
semantics.

The initial YANG mapping specifications are expressly defined for
NETCONF modeling.  However, there may be future areas of
applicability beyond NETCONF, and the WG must provide suitable
language extensibility mechanisms to allow for such future work.
The NETMOD WG will only address modeling NETCONF devices and the
language extensibility mechanisms.  Any application of YANG to
other protocols is future work.

The WG will consult with the NETCONF WG to ensure that NETMOD's
decision do not conflict with planned work in NETCONF (e.g.,
locking, notifications).

While it is desirable to provide a migration path from existing
MIBs to YANG data models, it is not a requirement to provide full
compatibility between SMIv2 and YANG. YANG is permitted to
introduce constructs that cannot be expressed in SMIv2.  However,
everything that can be expressed in SMIv2 must be expressible in
YANG.

Initial deliverables are below.  The working group may choose to
combine multiple deliverables into a single document where deemed
appropriate.

1. An architecture document explaining the relationship
between YANG and its inputs and outputs. (informational)

2. The YANG data modeling language and semantics (proposed
standard)

3. Mapping of YANG to XML instance data in NETCONF (proposed
standard)

4. A semantically equivalent two-way mapping to an XML-based
syntax for YANG (currently called YIN) (proposed standard)

5. Mapping of YANG to DSDL data modeling framework (ISO/IEC
19757) (proposed standard)

6. Definition of annotations for DSDL to preserve top-level
semantics during translation (proposed standard)

7. A standard type library for use by YANG (proposed standard)

Goals and Milestones:

Jun 2008 - All _individual_ drafts available that will be used as
input into the WG documents (draft-bjorklund-yang, architecture
draft, YIN draft, YANG standard library draft, DSDL mapping
draft?)

Aug 2008 - Initial set of WG drafts: architecture, YANG, YIN,
YANG standard library, DSDL mapping (if there is one/more
individual draft), based on WG decisions in Dublin

Sep 2008 - Initial DSDL mapping document

Oct 2008 - 01 of YANG, DSDL, architecture, YIN, and standard
library draft.  If split out, -00 of on-the-wire XML draft.

Feb 2009 - WGLC for architecture doc

Mar 2009 - Submit the architecture doc to the IESG for
publication as an Informational RFC

Aug 2009 - WGLC for YANG, YIN, XML on-the-wire (if split out),
YANG standard library, DSDL mapping

Sep 2009 - Submit YANG, YIN, XML on-the-wire (if split out), YANG
standard library, DSDL mapping to the IESG for publication as a
Proposed Standard
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---

From: Juergen Schoenwaelder <[email-masked]>
Date: Mon, 31 Mar 2008 22:01:35 +0200

On Mon, Mar 31, 2008 at 09:30:34PM +0200, David Partain wrote:

> everything that can be expressed in SMIv2 must be expressible in

The last sentence does not really make sense to me. What is the value
of translating say SMIv2 conformance definitions to YANG?

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1, 28759 Bremen, Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>
_______________________________________________
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https://www.ietf.org/mailman/listinfo/ngo

---

From: David Partain <[email-masked]>
Date: Mon, 31 Mar 2008 22:07:57 +0200

On Monday 31 March 2008 22.01.35 Juergen Schoenwaelder wrote:
> of translating say SMIv2 conformance definitions to YANG?'

Hi Jürgen,

Your comment was (pre-)echoed earlier today by Randy Presuhn, but we didn't 
have time to discuss that before our self-imposed deadline of sending it to 
NGO and I didn't feel like I could make the change without discussion.

He suggested "all basic types that can be represented in SMIv2 must be 
expressible in YANG." as an alternative.

In your view, would that be better?

Cheers,

David

---

From: Juergen Schoenwaelder <[email-masked]>
Date: Mon, 31 Mar 2008 22:14:10 +0200

> In your view, would that be better?

Since the mapping SMIv2 -> YANG is not part of the proposed NETMOD
charter, Randy's suggestion makes sense to me. A real mapping will of
course do much more but that is outside the charter anyways since
NETMOD is not going to work on SMIv2 -> YANG mappings - at least not
in within the proposed charter (if I read it correctly).

/js

---

From: "Romascanu, Dan (Dan)" <[email-masked]>
Date: Tue, 1 Apr 2008 10:42:59 +0200

I would like to thank the team for the work put into drafting the proposal for the charter. 

I would invite all interested parties to comment on the charter proposed by the team, including but not limited to 

- the scope of work
- the proposals that have been selected as starting points for NETMOD
- list of deliverables
- milestones

Please send your comments to the ngo list until April 7, COB. 

Thanks and Remarks,

Dan

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On 
> Behalf Of David Partain
> Sent: Monday, March 31, 2008 10:31 PM
> To: 'NETCONF Goes On'
> Subject: [NGO] A proposed WG Charter for NETMOD: NETCONF Data Modeling
> 
> Greetings,
> 
> creating a charter proposal for work in new working group as 
> a result of the many discussions, BoFs, semi-BoFs, bar 
> BoFs...  on a modeling language for NETCONF.  We did this at 
> the request of our O&M ADs.
> 
> The group included Alex Clemm, Balázs Lengyel, Bernd 
> Linowski, Bert Wijnen, David Harrington, David Partain, Jung 
> Tjong, Ladislav Lhotka, Martin Björklund, Martin Storch, 
> Mehmet Ersue, Phil Shafer, Randy Presuhn, Rohan Mahy, and 
> Sharon Chisholm.
> 
> We've worked very hard on this (LOTS of email), and, while we 
> don't all agree on every word, I believe we're all in 
> agreement on the general direction forward.
> 
> used for configuration management.  However, the NETCONF 
> protocol does not include a standard content layer.  The 
> specifications do not include a modeling language or 
> accompanying rules that can be used to model the management 
> information that is to be configured using NETCONF. This has 
> resulted in inconsistent syntax and interoperability 
> problems. The purpose of NETMOD is to support the ongoing 
> development of IETF and vendor-defined data models for NETCONF.
> 
> The WG will define a "human-friendly" modeling language 
> defining the semantics of operational data, configuration 
> data, notifications, and operations.  This language will 
> focus on readability and ease of use.  This language must be 
> able to serve as the normative description of NETCONF data 
> models.  The WG will use YANG (draft-bjorklund-yang) as its 
> starting point for this language.
> 
> reuse have been identified as a work area and will be 
> considered as a work item or may be integrated into the YANG 
> document based on WG consensus.
> 
> YANG-defined XML content.  Only data models defined in YANG 
> will have to adhere to this on-the-wire format.
> 
> In order to leverage existing XML tools for validating 
> NETCONF data in various contexts and also facilitate exchange 
> of data models and schemas with other IETF working groups, 
> the WG will define standard mappings from YANG to the DSDL 
> data modeling framework (ISO/IEC 19757) with additional 
> annotations to preserve semantics.
> 
> The initial YANG mapping specifications are expressly defined 
> for NETCONF modeling.  However, there may be future areas of 
> applicability beyond NETCONF, and the WG must provide 
> suitable language extensibility mechanisms to allow for such 
> future work.
> The NETMOD WG will only address modeling NETCONF devices and 
> the language extensibility mechanisms.  Any application of 
> YANG to other protocols is future work.
> 
> The WG will consult with the NETCONF WG to ensure that 
> NETMOD's decision do not conflict with planned work in 
> NETCONF (e.g., locking, notifications).
> 
> While it is desirable to provide a migration path from 
> existing MIBs to YANG data models, it is not a requirement to 
> provide full compatibility between SMIv2 and YANG. YANG is 
> permitted to introduce constructs that cannot be expressed in 
> SMIv2.  However, everything that can be expressed in SMIv2 
> must be expressible in YANG.
> 
> Initial deliverables are below.  The working group may choose 
> to combine multiple deliverables into a single document where 
> deemed appropriate.
> 
> Jun 2008 - All _individual_ drafts available that will be 
> used as input into the WG documents (draft-bjorklund-yang, 
> architecture draft, YIN draft, YANG standard library draft, 
> DSDL mapping
> draft?)
> 
> Aug 2009 - WGLC for YANG, YIN, XML on-the-wire (if split 
> out), YANG standard library, DSDL mapping
> 
> Sep 2009 - Submit YANG, YIN, XML on-the-wire (if split out), 
> YANG standard library, DSDL mapping to the IESG for 
> publication as a Proposed Standard