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Maintaining Consistency among Multiple Unit Representations

IP.com Disclosure Number: IPCOM000115865D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Barrett, KL: AUTHOR [+2]

Abstract

The method of representing multiple instances of an entity by a single object implies the necessity of maintaining consistency of the values of various slots of the object to reflect the correct values for the current instance. This disclosure presents a method of maintaining such consistency.

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Maintaining Consistency among Multiple Unit Representations

      The method of representing multiple instances of an entity by a
single object implies the necessity of maintaining consistency of the
values of various slots of the object to reflect the correct values
for the current instance.  This disclosure presents a method of
maintaining such consistency.

      The method of using a single object (called the MURMUR object)
to represent multiple instances of an entity is a powerful and
economical way of representing objects.  Since the context (defined
by the values of slots that determine the "current state") dictates
which one of the multiple entities is actually being represented at
any given moment, it is mandatory that changes in the context be
reflected properly in all the MURMUR objects that depend on the
context.  This can be done when a slot that is context dependant is
accessed.  However, for performance reasons it is useful to reflect
any changes in the current state in the MURMUR objects
instantaneously.  This can be accomplished by changing all context
dependant slots when one of the slots that comprises the context
changes its value.

      As an example, consider the IRRADH or IRRADL objects which
represent the upper and lower parts of the addresses for bus master
DMA operations.  There can be 16 register pairs (ADDR_REG_PAIR slot)
for each card.  There can be 16 cards (CARD slot) on each of the bus
units.  There can be four bus units (BUID slot).  Hence a total of
1024 possible registers exist.  Instead of creating 1024 instances of
essentially the same register, the MURMUR concept was used to create
just one object that represents all the 1024 instances by linkin...