[yang-doctors] policy for administrative key leaf values

[Andy Bierman <[e-mail]>]

Hi,

It would be nice to have a consistent guideline for designing admin keys.
This would improve interoperability

 Many modules use:

    leaf name { type string; }

There are many problems with this design, starting
with the fact that not one implementation in the world actually
supports the full 'string' character set. Developers must
use external info (not YANG) to know what is supported.

IMO the guidelines need to be updated and module
designers need to document the policies for a particular key leaf.
YD should refine and reach consensus on the guideline first.

Guidelines:
 - A typedef SHOULD be used for the key leaf type that
   specifies the following naming policies;

1) semantic policy
     It should be clear if the string has any semantics
     or is it purely an administrative string?

2) whitespace policy (leading, internal, trailing)

3) minimum length policy
   SHOULD be at least '1'.
   Need to justify need for zero-length identifiers.

4) maximum length policy
    - minimum max length (SHOULD be at least 64)
    - Use upper bound or 'max' in the length range.
       Use of 'max' can cause a too-big' error from a server.

5) special character policy
    - Are there any characters allowed by 'string' that can
      cause implementation-related problems or increase
      security risks?


Andy