INTRODUCTION

In this chapter, we shall give an illustration of the practical usefulness of our framework. We shall discuss a prototype system which has been developed to implement the structured tasks. It has been implemented on a Macintosh using Turbo Pascal. It enables the user to draw a hierarchy of DeMarco-like task diagrams and stores them as structured tasks, which are stored physically in the form of pointers and linked lists. It helps the user to review the task diagrams to an appropriate level of detail, and zoom in/zoom out to lower/higher levels through refinements and abstractions as required. Given an incomplete task specification, the system prompts the user to define further details of his design considerations. For example, if the user wants to build a hierarchical structure into a flat task diagram, he will be prompted to supply the necessary details such as the names of intermediate levels. Given a hierarchy of task diagrams, the system then transforms them automatically into a term algebra, a Yourdon structure chart and also Jackson structure text. An example of an application of the system will be given in Section 7.2. An overview of the system with examples of its algorithms will be given in Section 7.3.