Software Requirement Specification

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Chapter 8
Structuring System Requirements: Process Modeling

Chapter Overview

Chapter 8 introduces students to several process modeling techniques for representing business processes. Although this chapter focuses primarily on data flow diagramming, brief overviews of functional hierarchy modeling and Oracle’s process modeler are given.

After a brief introduction to process modeling, data flow diagramming techniques are introduced in a section called “Data Flow Diagramming Mechanics.” This section demonstrates the basic DFD symbols, definitions, and rules. The authors use the Gane and Sarson symbol set throughout the book, and these symbols are explained in this section. Hoosier Burger, the food ordering system first mentioned in Chapter 2, is used to illustrate basic data flow diagramming concepts. This section also includes explanations of decomposition and balancing.

Chapter 8’s third major section introduces four different types of DFDs: current physical, current logical, new logical, and new physical. Hoosier Burger’s inventory control system (which is manual) is used to illustrate the first three types of DFDs. Current practice in using DFDs indicates that very little time should be spent on the current physical DFD.

The fourth major section in this chapter, “Using Data Flow Diagramming in the Analysis Process,” introduces guidelines for drawing and using DFDs. This is different from the mechanical rules presented earlier. Topics include completeness, consistency, timing, iterative development, primitive DFDs, and analyzing DFDs for system inefficiencies and discrepancies among DFDs that are supposed to be modeling the same system. A Hoosier Burger example helps illustrate these guidelines.

The “Oracle’s Process Modeler and Functional Hierarchy Diagrams” section introduces students to two other process modeling tools. These tools are Oracle Designer’s process modeler and functional hierarchy modeling, a tool found in several CASE products. In this section, the authors show how to prepare basic process models and functional hierarchy diagrams. Additionally, the authors compare and contrast Oracle’s process models to data flow diagramming.

In the last section of this chapter, the authors’ overview process modeling for Internet-based electronic commerce applications. As they explain, process modeling for Internet-based electronic commerce applications does not differ from more traditional applications development projects.

Instructional Objectives

Specific student learning objectives are included at the beginning of the chapter. From an instructor’s point of view, the objectives of this chapter are to:

1.Show how to logically model processes with data flow diagrams.

2.Teach students data flow diagram symbols and the mechanical rules necessary to create accurate, well-structured process models.

3.Show students how to decompose data flow diagrams into lower-level diagrams.

4.Illustrate the concept of balanced DFDs.

5.Explain and demonstrate the differences among the four levels of DFDs: current physical, current logical, new physical, and new logical.

6.Illustrate how data flow diagrams are used as tools to support systems analysis.

7.Explain and stress the importance of the DFD guidelines: completeness, consistency, timing considerations, the iterative nature of drawing DFDs, and drawing primitive DFDs.

8.Discuss and illustrate Oracle Designer’s process modeler.

9.Discuss and illustrate functional hierarchical modeling.

10.Discuss processing modeling for Internet-based electronic commerce applications.

Classroom Ideas

1.Use Figures 8-2 and 8-6 to illustrate the basic DFD symbols and the correct and incorrect ways to draw data flow diagrams. Use Figure 8-3 to demonstrate the problem with trying to include sources/sinks inside the system being modeled.

2.Once you have covered the basics of drawing DFDs,...
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