Structured Design Methodologies

This tutorial considers the structure and construction of reliable software (see Figure 1). By way of introduction, several of the structured programming and software engineering techniques are classified into three groups; those which impact primarily on the program structure, the development process, and the development support tools. Structural Analysis Concepts are described which have their major impact at the code level, the module level, and the system level. Finally, three of the major structured design methodologies which have been reported in the literature are developed and compared. Functional Decomposition, the Data Flow Design Method, and the Data Structure Design Method are described, characterized, and applied to a specific example. While no one design methodology can be shown to be "correct" for all types of problems, it is felt that these three can cover a variety of applications. An "interim" approach for large software design problems is suggested which may be useful until an accepted "correct" methodology comes along.