Re: [netconf] [Technical Errata Reported] RFC8040 (6271)

[Martin Björklund <[e-mail]>]

Hi,

RFC Errata System <[e-mail]> wrote:
> The following errata report has been submitted for RFC8040,
> "RESTCONF Protocol".
> 
> --------------------------------------
> You may review the report below and at:
> https://www.rfc-editor.org/errata/eid6271
> 
> --------------------------------------
> Type: Technical
> Reported by: Kent Watsen <[e-mail]>
> 
> Section: 4.5
> 
> Original Text
> -------------
>    The "insert" (Section 4.8.5) and "point" (Section 4.8.6) query
>    parameters MUST be supported by the PUT method for data resources.
>    These parameters are only allowed if the list or leaf-list is
>    "ordered-by user".
> 
> 
> Corrected Text
> --------------
>    The "insert" (Section 4.8.5) and "point" (Section 4.8.6) query
>    parameters MUST be supported by the PUT method for data resources.
>    These parameters are only allowed if the target resource is a
>    non-existent entry of an "ordered-by user" list or leaf-list.

I don't think this is correct.  The new text makes it impossible to
move an existing ordered-by user list entry, which should be
possible.  4.8.6 says:

   The "point" query parameter is used to specify the insertion point
   for a data resource that is being created or moved within an
   "ordered-by user" list or leaf-list.

See below.


> Notes
> -----
> First, Section 3.5 (Data Resource) says that "list" and "leaf-leaf"
> are not a data resources:
> 
>   A data resource represents a YANG data node that is a descendant node
>   of a datastore resource. Each YANG-defined data node can be uniquely
>   targeted by the request-line of an HTTP method. Containers, leafs,
>   leaf-list entries, list entries, anydata nodes, and anyxml nodes are
>   data resources.
> 
> Second, these query parameters only make sense when targeting a
> non-existent entry.  If the entry does not exist, then PUT is being
> used like a POST: to create and place an item in an ordered list.
> However, if the entry exists, then PUT is being used to both replace
> the contents and (presumably) re-place the order in the list; but this
> doesn't make sense because:
> 
>   1) "insert" defaults to "last".
>   2) there is no "insert" value to indicate "keep existing placement".

I think this is the real problem.  It should be (and the intention was):

  1.  if "insert" isn't present and a new entry is created, the new
      entry will be appended to the end of the list.

  2.  if "insert" isn't present a an entry is modified (PUT), the
      entry keeps its place in the list.


/martin




>   3) having to concoct valid "insert" and "point" values is hard.
> 
> Thus indiscriminate PUTs would move entries to the end, which can't be
> desired...
> 
> Instructions:
> -------------
> This erratum is currently posted as "Reported". If necessary, please
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> 
> --------------------------------------
> RFC8040 (draft-ietf-netconf-restconf-18)
> --------------------------------------
> Title               : RESTCONF Protocol
> Publication Date    : January 2017
> Author(s)           : A. Bierman, M. Bjorklund, K. Watsen
> Category            : PROPOSED STANDARD
> Source              : Network Configuration
> Area                : Operations and Management
> Stream              : IETF
> Verifying Party     : IESG
> 
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