Application of Ada on a distributed missile control system

Abstract

A system for distributing a single Ada program to a network of loosely coupled computers is described. The system is applied to the distribution of a missile control system. We have found that implementing the entire Ada semantics for distributed systems is difficult, but that a pragmatic approach can give reasonable semantics. Our approach is based on source code transformation of the single Ada program into multiple Ada programs. These programs are then compiled with a standard compiler. The units of distribution are tasks and task types, subprograms, and variables. Restrictions are implied by the task termination semantics, the exception propagation between nodes, and the synchronization of tasks at activation.

Distribution of Ada tasks onto a heterogeneous environment

“…Some use tasks, task types, subprograms and variables as distribution units [3], and others use packages [5]. Using packages or variables as distribution units could be considered even in a heterogeneous environrnen~but we did not for two reasons.…”

“…Several projects translate a single Ada program to multiple Ada programs ( [2], [3]), Ada-to-Ada translation is easy because major portions of the source code require no modification. On the other luu@ the C language is useful as a target language since almost ail CPU board vendors support C. We selected C so that we could use severat kinds of CPUS.…”