TI An Object-Based Programming Model for Shared Data 

LT CUCS-046-90 

OR COLUM 

YR 1990 

AU Gail E. Kaiser 

AU Brent Hailpern" 

MN May 

YR 1990 

AV ftp cs.columbia.edu:pubreportsreports-1990cucs-046?-90.ps.Z 

AB The classical object model supports private data within
objects and clean interfaces between objects, and by definition
does not permit sharing of data among arbitrary objects.  This is
a problem for real-world applications --- such as advanced
financial services and integrated network management --- where
the same data logically belongs to multiple objects and may be
distributed over multiple nodes on the network.  Rather than give
up the advantages of encapsulated objects in modeling real-world
entities, we propose a new object model that supports shared data
in a distributed environment.  The key is separating distribution
of computation units from information hiding concerns.  Minimal
units of data and control, called {\it facets}, may be shared
among multiple {\it objects} and are grouped into {\it
processes}.  Thus a single object, or information hiding unit,
may be distributed among multiple processes, or computation
units.  In other words, different facets of the same object may
reside in differentddress spaces on different machines.  We
introduce our new object model, describe a motivating example
from the financial domain and then explain facets, objects and
processes, followed by timing and synchronization concerns.