CLEOPATRA: A C-based Language for the Event-driven
	     Object-oriented Prototyping of Asynchronous
		  Time-constrained Reactive Automata


			    Azer Bestavros



Predictability -- the ability to foretell  that an implementation will
not violate a set of specified reliability and timeliness requirements
-- is a   crucial, highly desirable   property of responsive  embedded
systems. In my PhD research I have  proposed and partially implemented
a  development  methodology  for  responsive  systems,  which enhances
predictability   by  eliminating  potential   hazards   resulting from
physically-unsound specifications.

The  backbone of   my methodology   is  the Time-constrained  Reactive
Automaton (TRA) formalism, which adopts a  fundamental notion of space
and time  that   restricts expressiveness  in  a way  that  allows the
specification of  only reactive, spontaneous, and  causal computation.
Using the TRA model, unrealistic systems -- possessing properties such
as  clairvoyance, caprice,  infinite capacity,  or  perfect timing  --
cannot even be  specified. I argue that this  "ounce of prevention" at
the specification level is likely to spare a lot of time and energy in
the  development cycle of responsive   systems  -- not to mention  the
elimination of  potential  hazards that  would   have gone, otherwise,
unnoticed.

The TRA model is presented to system  developers through the CLEOPATRA
programming language. CLEOPATRA  features a  C-like imperative  syntax
for   the  description   of computation,   which  makes  it  easier to
incorporate in applications already using  C. It is event-driven,  and
thus  appropriate for embedded   process control applications.  It  is
object-oriented   and  compositional,  thus  advocating modularity and
reusability. CLEOPATRA  is  semantically  sound;  its objects  can  be
transformed, mechanically  and unambiguously, into formal TRA automata
for  verification purposes, which  can be pursued using model-checking
or theorem proving techniques.  Since  1989, an ancestor  of CLEOPATRA
has  been  in use  as a   specification  and  simulation language  for
embedded time-critical robotic processes.


Collaborators:
-------------
o Thomas E. Cheatham  (Harvard  University) supervised my thesis  work
  while I was at Harvard. 

o As part of their Masters' project at Boston University, Devora Reich
  and  Robert Popp wrote   a translator  that  allows  the  simulation
  of system specifications written in CLEOPATRA.  


Funding:
-------
This research is funded by a grant from NSF (grant CCR-9308344).