Dynamic Encapsulation of C++ Objects
                 for Distributed Object-Oriented Systems

                               Presented By
                             Frank E. Barrus
       ____________________________________________________________
                 What:  Masters Thesis Defense
                 When:  10-11AM; Thursday, June 19, 1997
                 Where: Conference Room 10-1124
                  anyone interested is welcome to attend
       ____________________________________________________________


                                 ABSTRACT

            Classes in C++ provide static encapsulation of objects,
       by generating code which contains specific  knowledge  about
       the internals of encapsulated objects.  Static encapsulation
       occurs at compile time, and therefore cannot  directly  sup-
       port the evolution of objects, since recompilation of source
       code is required if the internal layout changes. This  also
       prohibits the use of distributed or persistent objects with-
       out first ensuring that the internal representations of  the
       objects match the ones in the compiled code.
            Dynamic  encapsulation  occurs  at run-time, and allows
       the compiled code to exist without the knowledge of any par-
       ticular  object  representation. Abstract base classes with
       C++ virtual functions support  a limited  form   of  dynamic
       encapsulation, but only for objects originally designated to
       inherit that class.  Some languages, such as Smalltalk, sup-
       port  dynamic  encapsulation, but without the performance of
       statically encapsulated languages.
            An object model using dynamic type-binding is presented
       that  allows  the  flexibility of dynamic encapsulation with
       much of the efficiency of static encapsulation.  With  this
       model,  objects  can  potentially  communicate  and  migrate
       across address space and network boundaries without specific
       prior knowledge of representations, and can invoke functions
       on local objects with no more run-time overhead  than  stan-
       dard C++ virtual function calls.
            This  dynamic  encapsulation model is incorporated into
       DC++, a set of dynamic extensions to the C++  language  that
       allows   for  the  dynamic  encapsulation  of  existing  C++
       objects, and DECO (Dynamic Encapsulator of C++  Objects),  a
       utility for converting DC++ source code to C++.


                            Faculty Advisors:
                       Professor Andrew T. Kitchen
                      Professor Warren R. Carithers
                       Professor Peter G. Anderson