Re: [core] New Version Notification for draft-bierman-core-yid-00.txt

[Andy Bierman <[e-mail]>]

On Tue, Aug 23, 2016 at 8:24 AM, Michel Veillette <
[e-mail]> wrote:

> Hi Andy
>
>
>
> draft-bierman-core-yid-00 propose that only manually assigned YIDs
>
> are maintained in the registry (mapping list or mapping-url). YIDs
> associated to a
>
> hash are excluded from this registry.
>
>
>
> This solution doesn't seem to work if the following design objectives
> listed in
>
> section 1.2 need to be respected:
>
>
>
> 1- Persistent Identifiers: It is important that once an identifier is
>
> assigned, that is it never changed in any future revisions in the
>
> module.
>
>
>
> 1- Module updates need be simple, and only require the latest module
>
> and registry information.
>
>
>
> For example, YANG module X is created with:
>
> Data node A associated to YID = hash 1
>
> Data node B associated to YID = hash 2
>
> Data node C associated to YID = hash 3
>
>
>
> Than, a new revision is created with:
>
> Data node D associated to YID = hash 2
>
> Data node E associated to YID = hash 4
>
>
>
> Is this example, we have a hash clash between data node B and D.
>
> However, the YID assigned to data node B by version 1 is not allowed to
> change (objective #1).
>
> Only data node D can be rehashed.
>


So the manual entry will be for D, not B. not a problem.



>
>
> Using only the latest module (objection #2) and no entry in the registry,
> the proper rehash can't be performed.
>


Agreed. You do need the current registry entry to create
an update to that entry.




> A simple solution to this problem is to maintain all YIDs in the registry.
>
> A new entry is rehashed only if a clash is detected with an entry already
> present in the registry.
>


Agreed.
This also makes SID registry maintenance simple.
(Number only the nodes not already present in version N to produce N+1).

No matter how the YANG module can possibly be changed over time,
the path identifiers remain the same from version to version,
and therefore the hashes remain the same.




>
>
> In summary, the process is the same independently of the algorithm in used
> (sequential, murmur3 hash, manual).
>


yes



> Each time an YID is assigned, it must be added to the registry.
>
> And new entries are not allowed to collide with entries already present in
> the registry.
>
>
>
> The standard may describe these different algorithms (murmur3 hash,
> sequential, manual)
>
> but don’t need to mandate one.
>
>
>
> Regards,
>
> Michel
>
>
>

Andy


> *From:* core [mailto:[e-mail]] *On Behalf Of *Andy Bierman
> *Sent:* Tuesday, August 16, 2016 2:39 PM
> *To:* Core <[e-mail]>
> *Subject:* [core] Fwd: New Version Notification for
> draft-bierman-core-yid-00.txt
>
>
>
> FYI,
>
>
>
>
>
> Peter and I have written a new draft called "Numeric YANG Identifiers"
>
> which replaces the "YANG Hash" draft.
>
>
>
> This draft combines hash-based and manual numbering and defines
>
> a simple registry-based process for management of module and object
> identifiers.
>
>
>
> The need for a rehash procedure and rehash errors has been removed.
>
> YANG Hash is now scoped by the module identifier so there are no
> inter-module
>
> interactions.  Hash collisions within a module are not allowed.
>
> Manual assignments for colliding nodes are used to avoid the rare
> occurrence
>
> of a hash collision within the same module.
>
>
>
>
>
>
>
> Andy
>
>
>
>
>
> ---------- Forwarded message ----------
> From: <[e-mail]>
> Date: Tue, Aug 16, 2016 at 11:29 AM
> Subject: New Version Notification for draft-bierman-core-yid-00.txt
> To: Peter van der Stok <[e-mail]>, Andy Bierman <
> [e-mail]>
>
>
>
> A new version of I-D, draft-bierman-core-yid-00.txt
> has been successfully submitted by Andy Bierman and posted to the
> IETF repository.
>
> Name:           draft-bierman-core-yid
> Revision:       00
> Title:          Numeric YANG Identifiers
> Document date:  2016-08-16
> Group:          Individual Submission
> Pages:          33
> URL:            https://www.ietf.org/internet-
> drafts/draft-bierman-core-yid-00.txt
> Status:         https://datatracker.ietf.org/doc/draft-bierman-core-yid/
> Htmlized:       https://tools.ietf.org/html/draft-bierman-core-yid-00
>
>
> Abstract:
>    This document describes an encoding of YANG object identifiers using
>    numeric values instead of string values.  It combines several
>    techniques to provide optimized serialization in protocol messages.
>
> Note
>
>    Discussion and suggestions for improvement are requested, and should
>    be sent to [e-mail].
>
>
>
>
> Please note that it may take a couple of minutes from the time of
> submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> The IETF Secretariat
>
>
>