High Order Software: A Methodology for Defining Software

The key to software reliability is to design, develop and manage software with a formalized methodology which can be used by computer scientists and applications engineers to describe and communicate interfaces between systems. These interfaces include: software to software; software to other systems; software to management; as well as discipline to discipline within the complete software development process. The formal methodology of Higher Order Software (HOS), specifically aimed toward large-scale multiproqrammed/multiprocessor systems, is dedicated to systems reliability. With six axioms as the basis, a given system and all of its interfaces is defined as if it were one complete and consistent computable system. Some of the derived theorems provide for: structuring of real-time multiproqrammed processes, communication between- functions and prevention of data and timing conflicts.

The first step in defining a system with a formal methodology is to apply a formalized set of rules. We have found that enforcing such rules, especially on a large project with many organizations, is very difficult. In fact, it is almost impossible without the aid of automated tools to describe the design process and its verification. The definition of a given system can be described with an HOS meta-language which, by its very nature, enforces the axioms with the use of each construct. A system defined in HOS is analyzed automatically for axiomatic consistency by the design analyzer, without program execution, and by the structuring executive analyzer on a real-time basis. The result fs that a software system can be developed efficiently with reliable interfaces. This is especially significant since interface testing in a large system accounts for approximately 75% of the verification effort.