RE: Inconsistencies in QDDIM -07 Draft

Bob, I think that the operative words in my email are "IF you define a
CalculationService, then ..."  Since CalculationService is a new concept and
may not be visibly instrumented, I did not want to make it mandatory.
Hence, the 0..n on the CalculationService, as related to a REDDropper.  I
think that the "one or more" wording in the Description is a cut and paste
error.

Andrea
  -----Original Message-----
  From: [email protected] [mailto:[email protected]]
  Sent: Wednesday, May 29, 2002 10:36 AM
  To: Andrea Westerinen
  Cc: Policy@Ietf. Org
  Subject: Re: Inconsistencies in QDDIM -07 Draft


  Hi Andrea,

  Busy editing QDDIM ....

  From CR 795:

  // ==================================================================
  // CalculationServiceForDropper
  // ==================================================================
  [Association, Experimental, Version ("2.7.0"),
  Description (
  "This association is a subclass of ServiceServiceDependency, "
  "and represents the reliance of a REDDropperService on one or "
  "more DropThresholdCalculationServices. The latter calculate "
  "average queue depth, based on the observed depths of a "
  "queue. The specific queue examined by each CalculationService "
  "is defined using the CalculationBasedOnQueue association.") ]
  class CIM_CalculationServiceForDropper : CIM_ServiceServiceDependency {
  [Override ("Antecedent"), Description (
  "A calculation service for the dropper.") ]
  CIM_DropThresholdCalculationService REF Antecedent;
  [Override ("Dependent"), Description (
  "The RED dropper which is dependent on average queue depth "
  "calculations by the Antecedent Service.") ]
  CIM_REDDropperService REF Dependent;
  };

  For the calculation service, the words say "one or more", but the
cardinality says 0..n. You also propose 0..n for QDDIM, but I think that the
words are correct here - the cardinality should be 1..n, since the only path
to get from a RED dropper to a queue for it to examine is via a calculation
service instance.

  Assuming that you'll say "Yes, of course," I've tentatively gone with 1..n
in the QDDIM update. You can still talk me out of this is you're quick.

  Otherwise, I've edited QDDIM as you've proposed in this note.

  Regards,
  Bob

  Bob Moore
  Advanced Design and Technology
  Application Integration Middleware Division
  IBM Software Group
  +1-919-254-4436
  [email protected]

  "Andrea Westerinen" <[email protected]>





                "Andrea Westerinen" <[email protected]>
                05/14/02 06:28 PM


        To: "Policy@Ietf. Org" <[email protected]>, Robert
Moore/Raleigh/IBM@IBMUS
        cc:
        Subject: Inconsistencies in QDDIM -07 Draft



  In reading QDDIM very closely :-), I noticed some inconsistencies in the
text in Section 3, in the formal class definitions in Section 4, and in the
intent. Here are my observations and recommendations ...

  1. For RED droppers, I think that we wanted the following ...
  A REDDropperService can be related to many
DropThresholdCalculationServices (many to many), but each CalculationService
examines a single queue (many to one).

  2. This means that ...
  IF you define a DropThresholdCalculationService, you really MUST specify
the queue that is examined. So, CalculationBasedOnQueue should have a
cardinality of 1..1 on the QueuingService side (currently it has 0..1).
  AND
  A REDDropper MAY be associated with one or more CalculationServices (each
looking at a specific queue). So, CalculationServiceForDropper should have a
cardinality of 0..n on the DropThresholdCalculationService side (currently
it is a mandatory 1).

  3. For a HeadTailDropperService, its determinations can also be based on
several queues (as discussed at the bottom of page 23). So,
HeadTailDropQueueBinding should have a cardinality of 1..n for the
QueuingService (currently, it has mandatory 1). I agree that at least queue
is mandatory - but more than one can be examined.

  Andrea