This is a pre-print of a copyrighted article in IEEE Parallel and Distributed Technology, vol. 1, no. 3, August 1993.

el programming environments for distributed memory applications. He received an MS (in 1992) and a BS (in 1991) in computing science from the University of Alberta, and a BS in chemistry from the University of Western Ontario in 1978. Greg Lobe is works for Bell Northern Research in Ottawa. His research interests include object-oriented and parallel programming. He received his MS and BS in computing science from the University of Alberta in 1993 and 1989 respectively. This is a pre-print of a copyrighted article in IEEE Parallel and Distributed Technology, vol. 1, no. 3, August 1993. Introduction Designing, implementing, and testing distributed software is considerably more difficult than for comparable sequential software. There are efficient parallel algorithms for a large class of problems, but finding the right one can be only a small part of the implementation cost. Writing distributed software is also complicated by problems not found in the sequential environment, inc