Re: [netmod] WG Last Call: draft-ietf-netmod-schema-mount-07

[Juergen Schoenwaelder <[e-mail]>]

On Fri, Nov 10, 2017 at 04:39:36PM +0100, Ladislav Lhotka wrote:
> >
> > So what is the difference between "schema tree" and "schema"? Or to
> > put it differently, what is "all associated semantics" that you are
> > adding to a "schema tree" to obtain a "schema"? RFC 7950 says:
> >
> >    o  schema tree: The definition hierarchy specified within a module.
> 
> As Rob points out, this is probably incorrect, as schema tree should
> involve multiple modules. It makes no sense to talk about a schema tree
> of an augmenting module unless we also take into account the augmented
> module.
> 
> Anyway, schema tree is really just the hierarchy, i.e. a tree of schema
> nodes, whereas schema is the hierarchy with datatypes, semantic rules
> and all that. We can validate instance data against the schema, not
> against the schema tree. This is at least how I understand it.

The current definition says "definition hierarchy specified within a
module", perhaps this was intended to mean 'tree of schema nodes', but
perhaps it means "the hierarchy with datatypes, semantic rules and all
that". ;-) Looking at the definition of schema node, I see:

  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.

With this, your interpretation makes sense and a better way to define
scheme tree would then be:

  o schema tree: The tree formed out of schema nodes of a module.

The schema could be defined as

  o schema: All definitions of a module including the schema tree.

I think it is OK to scope these definitions to the notion of a module.
If people talk about the schema (schema tree, schema nodes) of a
collection of modules, it seems natural to assume that this means the
union of the schemas (schema trees, schema nodes).

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
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