Translation And Execution Of Distributed ADA Programs: Is It Still ADA?

Abstract

Intelligent control of Space Station will require the coordinated execution of computer programs across a substantial number of computing elements. It will be important to develop large subset of these programs in the form of single programs which execute in a distributed fashion across a number of processors. The single program approach to programming closely coordinated actions of multiple computers allows the advantages of language level software engineering developments, e.g., abstract data types, separate compilation of specifications and implementations, and extensive compile time error checking, to be fully realized across machine boundaries. As yet, however, there are few implementations of distri-buted execution systems. Ada has been adopted for use in the Space Station, and the Ada Language Reference Manual indicates that distributed execution of Ada programs was in the minds of the language designers. However, when considered from the perspective of distributed execution, there are several aspects of the language definition which need further refinement, and a number of difficult trade-off decisions to be made in terms of translation strategies. This paper examines some of the fundamental issues and trade-offs for distributed execution systems for the Ada language.