PCLS classes deprecated in PCELS
2003-09-04 22:09:46 GMT
PCELS deprecates some of the PCLS classes and attributes for various reasons. In some cases, deprecation could have been avoided but in other cases this was dictated by PCIMe. (details discussed below) I agree that deprecation might create backward compatibility problems where PCELS and PCLS implementations attempt to cooperate. BTW, does anybody out there have such requirements? Given that PCIMe deprecates a significant number of concepts from PCIM, is such cooperation even possible?
The classes deprecated by PCELS are discussed below:
1. The class pcimGroupContainmentAuxClass defined by PCLS provides a single, multi-valued attribute that references a set of pcimGroups. This unordered aggregation mechanism can not be reused in implementations of PCIMe because the model (PCIMe) requires PolicySetComponent associations to be prioritized:
" 5.5. Priorities and Decision Strategies
[...] Unlike the earlier definition,
PolicySetComponent.Priority MUST have a unique value when compared
with others defined for the same aggregating PolicySet. Thus, the
evaluation of rules within a set is deterministically specified. "
If PCELS allowed pcimGroupContainmentAuxClass, then it would be conflicting with PCIMe.
2. The class pcimRuleContainmentAuxClass defined in PCLS is deprecated by PCELS for the same reasons.
3. The pcimRule* classes defined by PCLS are deprecated and redefined as pcimPolicyRule* in PCELS. According to PCIMe the PolicyRule.Priority property is deprecated. Therefore PCELS redefines the PolicyRule class mainly for removing the Priority attribute. An other option would have been to leave pcimRule* as they are and then PCELS would have had to specify that the pcimRulePriority attribute MUST NOT be used - a less formal solution that does not prevent accidental use of the deprecated attribute.
An other reason for replacing the pcimRule* classes is the renaming of the attributes that serve in the Rule-Condition and Rule-Action associations. pcimRuleConditionList is replaced by pcimConditionList and pcimRuleActionList is replaced by pcimActionList. Thus, the new attributes along with the new association classes (discussed below) offer a generic mechanism for aggregating Conditions or Actions. The use the same Condition/Action aggregation mechanism for both Policy Rules and Compound Conditions/Action is an optimization in line with the Policy*Structure concepts defined by PCIMe.
The deprecation of the pcimRule* classes is certainly not the only option but based on our experience implementing PCIMe this one seemed an acceptable compromise. However, any opinions or suggestions from the WG based on their experience would be greatly appreciated.
4. The class pcimRuleConditionAssociation defined by PCLS has probably less reasons to be deprecated. It was done simply to keep the Condition aggregation (into rules or compound conditions) limited to a single association class. Now, looking from this different prospective, I think that it is a good idea to retain it.
So, I suggest the modification of the pcimRuleConditionAssociation to become a subclass of the pcimConditionAssociation already defined in PCELS. The attributes of the pcimRuleConditionAssociation, all inherited from its superclass, would end up being the same ones as previously defined by PCLS. Thus, for aggregating Conditions into a Policy Rule, one would have the choice of using pcimConditionAssociation or pcimRuleConditionAssociation while Condition aggregation into a Compound Condition would be realized only through the pcimConditionAssociation class.
5. pcimRuleActionAssociation - same suggestion as for the pcimRuleConditionAssociation class
6. The pcimRepository class defined by PCLS is deprecated by PCELS for reasons described in PCIMe:
" Because of the potential for confusion with the Policy Framework
component Policy Repository (from the four-box picture: Policy
Management Tool, Policy Repository, PDP, PEP), "PolicyRepository" is
a bad name for the PCIM class representing a container of reusable
policy elements. Thus the class PolicyRepository is being replaced
with the class ReusablePolicyContainer."
> -----Original Message-----
> From: Wijnen, Bert (Bert) [mailto:bwijnen <at> lucent.com]
> Sent: Friday, August 29, 2003 11:15 AM
> To: policy <at> ietf.org
> Subject: RE: [Policy] Re: draft-reyes-policy-core-ext-schema-03.txt
> What an underwhelming interest in this document.
> When I start reading it, I see in the abstract:
> This document defines a number of changes and extensions to the
> Policy Core LDAP Schema [PCLS] based on the specifications of the
> Policy Core Information Model Extensions [PCIM_EXT]. The changes
> include additional object classes previously not covered,
> of some object classes and changes to the object class hierarchy
> defined in [PCLS].
> And so I immediately wonder... is it really OK that this document
> deprecates some object classes ??
> Possibly so... but I'd like to hear some of the PCIM, PCIM-EXT and
> PCLS authors/ediotrs to explicitly say so. PLEASE!
> > -----Original Message-----
> > From: Wijnen, Bert (Bert) [mailto:bwijnen <at> lucent.com]
> > Sent: vrijdag 15 augustus 2003 11:45
> > To: policy <at> ietf.org
> > Subject: RE: [Policy] Re: draft-reyes-policy-core-ext-schema-03.txt
> > Joel asked from the WG:
> > > -----Original Message-----
> > > From: Joel M. Halpern [mailto:joel <at> stevecrocker.com]
> > > Sent: woensdag 6 augustus 2003 17:33
> > > To: policy <at> ietf.org
> > > Subject: [Policy] Re: draft-reyes-policy-core-ext-schema-03.txt
> > >
> > >
> > > The revised Internet draft is now available in the I-D repository:
> > > http://www.ietf.org/internet-drafts/draft-reyes-policy-core-ex
> > > t-schema-03.txt
> > >
> > > I believe it is appropriate for this document to go forward as an
> > > individual contribution that has been reviewed by a (our)
> > working group.
> > > As such, I will give folks one more chance to comment
> > before indicating
> > > that the author's can (and should) contact the AD for this.
> > > Please respond by August 20 (preferably sooner) with any
> > > concerns, issues, etc. It would even be helpful if folks
> > would merely
> > > indicate that they had read and liked the document.
> > >
> > So did anyone actually READ (or even BROWSE) the document???
> > PLEASE be active and participate!
> > Bert
> > > Thank you,
> > > Joel M. Halpern
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