[netmod] Definitions of YANG schema and Packages (in packages draft) - Issue #74

["Sterne, Jason (Nokia - CA/Ottawa)" <[e-mail]>]

Hi all,

This email is related to the items (a) and (c) in Issue #74 of the YANG versioning work:
https://github.com/netmod-wg/yang-ver-dt/issues/74

========================================================
First some background:

"YANG schema" is not defined in RFC7950 or 8342 (NMDA).

8342 defines the following:

   o  schema node: A node in the schema tree.  The formal definition is
      provided in RFC 7950.

   o  datastore schema: The combined set of schema nodes for all modules
      supported by a particular datastore, taking into consideration any
      deviations and enabled features for that datastore.

7950 defines the following:

   o  schema node: A node in the schema tree.  One of action, container,
      leaf, leaf-list, list, choice, case, rpc, input, output,
      notification, anydata, and anyxml.

   o  schema tree: The definition hierarchy specified within a module.

========================================================
Some current definitions in YANG Packages 02 https://datatracker.ietf.org/doc/draft-ietf-netmod-yang-packages/

Abstract

   This document defines YANG packages, a versioned organizational
   structure holding a set of related YANG modules that collectively
   define a YANG schema.

Section 1:

   *  YANG schema:  A datastore schema, not bound to any particular datastore.

   *  YANG package: An organizational structure containing a collection
      of YANG modules, normally defined in a YANG instance data file.  A
      YANG package defines a YANG schema by specifying a set of YANG
      modules and their revisions, other packages and their revisions,
      mandatory features, and deviations.  YANG packages are defined in
      Section 5.

Section 2:

   A YANG package is an organizational structure that groups a set of
   YANG modules together into a consistent versioned definition.

Section 5:

   A YANG package is a versioned organizational structure defining a set
   of related YANG modules, packages, features, and deviations.  A YANG
   package collectively defines a YANG schema.

========================================================
Proposed updates to the packages draft (changes highlighted in red)
- unify the short description of a package in the 4 places (don't try to include all details of a package in this short description)
- but do we need more than this short description in the abstract and sections 1 and 2 ?
- do we even need a term called "YANG Schema" ?

Abstract

   This document defines YANG packages: a versioned organizational
   structure defining a set of YANG modules, features, and deviations.

Section 1:

   This document also makes of the following terminology introduced in
   the YANG 1.1 Data Modeling Language [RFC7950]:

   *  data node

   *  schema node

   In addition, this document defines the following terminology:

  * YANG schema: The combined set of schema nodes for a set of modules, taking into consideration any deviations and enabled features.

   * YANG package: A versioned organizational structure defining a set of YANG modules, features, and deviations.  A YANG package collectively defines a YANG schema.
- leave out "normally defined in a YANG instance data file"
- leave out "other packages and their revisions"
- leave out "submodules"
- leave out anything about mount points
- "set" vs "collection" vs "groups" vs "holding" of YANG modules:   use "set" of YANG modules

Section 2:

   A YANG package is a versioned organizational structure defining a set of YANG modules, features, and deviations.  For
   example, a YANG package could define the set of YANG modules required
   to implement an L2VPN service on a network device.  YANG packages can
   themselves refer to, and reuse, other package definitions.
[or add mentions of included packages and mount points here in section 2 ? section 1? abstract ?]

Section 5:

   A YANG package is a versioned organizational structure defining a set
   of related YANG modules, packages, features, and deviations.  A YANG
   package collectively defines a YANG schema.

Jason