Subject: PCIM-06

From: [email-masked]
Date: Thu, 11 May 2000 08:58:15 -0400

An update to the PCIM, draft-ietf-policy-core-info-model-06.txt,
is now available on the Internet-Drafts repository.  This update
was done in response to an IESG comment pointing out that the
handling of time zone information in PCIM-05 was inadequate.  The
update also contains a general cleanup item, and a change that
removes some text that might be appropriate for the LDAP
representation of the model, but is not appropriate for the
PCIM itself.  Specifically:

1. The time zone issue concerned the use of UTC offsets.  In PCIM-05,
   the ApplicableTimeZone property allowed times to be specified
   with a numeric offset (+ or -) from UTC time -- for example,
   -0500 for [US] Eastern Time.  The iCalendar spec (RFC 2445),
   however, explains that while numeric offsets from UTC are fine
   for past times, they are not sufficient for future intervals of
   time that span Daylight Savings Time transitions.  A new section
   5.4 in PCIM-06 provides more details on this issue, and explains
   how it is being addressed in the PCIM.

2. There are also two changes unrelated to time zones that I made in
   PCIM-06.  In both cases these involved the removal of obsolete
   text that should have been removed back in PCIM-03 or PCIM-04, but
   was missed.

   The two paragraphs that I removed:

      Since conditions may be defined explicitly in a subclass of
      PolicyRule, the AND/OR mechanism to combine these conditions
      with other (associated) PolicyConditions MUST be specified by
      the PolicyRule's subclass.  (section 7.6)

      For actions defined explicitly in a subclass of PolicyRule,
      the ordering mechanism must be specified in the subclass
      definition.  (section 7.10)

   The problem with both of these passages is that we introduced text
   in these sections stating that

      A policy rule that aggregates zero policy conditions [actions]
      is not a valid rule -- it may, for example, be in the process
      of being entered into the policy repository.

   In making this change, to allow for better automated detection of
   invalid policy rules, we legislated out of existence the cases
   that the two paragraphs were referring to.

   I don't regard these two deletions as technical changes to the
   PCIM -- they're just editorial cleanup that should have happened
   long ago.

3. Finally, I removed some "lingering LDAP" flavor from the two
   associations PolicyGroupInSystem and PolicyRuleInSystem, to
   parallel changes that were made during final WG review in the
   DMTF.  Formerly, the relationship between a policy group or
   policy rule and the system it applies to was expressed in terms
   of "containment".  While this might be how these associations
   are represented when the information model is mapped to LDAP,
   in the model itself they are more correctly characterized as
   ones of scope, not containment.

Regards,
Bob

Bob Moore
IBM Networking Software
+1-919-254-4436
[email-masked]