Objectives: Introduction Over View of System Analysis and Design
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- 8.5.3.1 Functional Diagrams
- 8.5.4 Warinier/Orr Diagrams
| 8.5.3 Visual Table of contents The visual table of contents (VTOC) shows the relation between each of the documents making up a HIPO package. It consists of a hierarchy chart that identifies the modules in a system by number and in relation to each other and gives a brief description of each module. The numbers in the contents section correspond to those in the organization section. The modules are in increasing detail. Depending on the complexity of the system, three to five levels of modules are typical. 8.5.3.1 Functional Diagrams There is one diagram for each box in the VTOC. Each diagram shows input and output (right to left or top to bottom, major processes, movement of data, and control points. Traditional flowchart symbols represent media, such a magnetic tape, magnetic disk, and printed output. A solid arrow shows control paths, and open arrow identifies data flow. Some functional diagrams contain other intermediate diagrams. But they also show external data, as well as internally developed data (such as tables in the invoice example) and the step in the procedure where the data are used. A data dictionary description can be attached to further explain the data elements used in a process. HIPO diagrams are effective for documenting a system. They also aid designers and force them to think about how specifications will be met and where activities and components must be linked together. However, they rely on a set of specialized symbols that require explanation, an extra concern when compared to the simplicity of, for example, data flow diagrams. HIPO diagrams are not as easy to use for communication purposes as many people would like. And, of course, they do not guarantee error-free systems. Hence, their, greatest strength is the documentation of a system. 8.5.4 Warinier/Orr Diagrams Warnier/Orr diagrams (also known as logic construction of programs/logical construction of system) were initially developed in France by Jean – Dominique Warnier and in the United States by Kenneth Orr. This method aids the design of program structures by identifying the output and processing results and then working backwards to determine the steps and combinations of input needed to produce them. The simple graphic methods used in Warnier/Orr diagrams make the levels in the system evident and the movement of the data between them vivid. Download 0.94 Mb. Share with your friends:
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