A Visual Execution Model for Ada Tasking

A visual execution model for Ada tasking can help programmers attain a deeper understanding of the tasking semantics. It can illustrate subtleties in semantic definitions that are not apparent in natural language descriptions of Ada tasking, as well as the consequences of choices made in the language design. We describe a contour model of Ada tasking that depicts asynchronous tasks (threads of control), relationships between the environments in which tasks execute, and the manner in which tasks interact. The use of this high-level execution model makes it possible to see what happens during execution of a program. The paper provides an introduction to the contour model of Ada tasking and demonstrates its use. 1 Introduction The Ada programming language is intended for use in real-time applications such as flight navigation or process control software. For this reason, tasking figures prominently in the language design. The semantics of tasking, however, is extremely complex. At the sa..