1 9 Moving to Design Lecture 4

2 9 Analysis Objectives to Design Objectives Figure 9-2

3 9 Understanding the Elements of Design u Design is the process of describing, organizing, and structuring the components of a system at both the architectural level and at a detailed level l Focused on construction l Like developing blueprints u Three questions l What components require systems design? l What are the inputs to and outputs of the design process? l How is systems design done?

4 9 Inputs and Outputs: Moving from Analysis to Design u Design: l Converts functional models from analysis into models that represent the solution l Focused on technical issues l Requires less user involvement than analysis

5 9 SDLC Phases with Design Phase Activities Figure 9-4 Design and Integrate Network Design the Application Architecture Design the User Interfaces Design the System Interfaces Design and Integrate the Database Prototype for Design Details Design and Integrate System Controls

6 9 Structured Approach to Designing the Application Architecture u Application software programs l Designed in conjunction with database and user interfaces l Hierarchy of modules u Documented with system flowcharts u Design internal program logic u Top-down approach l DFDs with automation boundaries l Structure charts

7 9 Structured Design Models Figure 9-7

8 9 Automation System Boundary u Partitions data flow processes into manual and automated systems u Processes can be inside or outside boundary u Data flows can be inside and outside of boundary

9 9 DFD with Automation System Boundary Figure 9-8

10 9 System Flowchart u Representation of various computer programs, files, databases, and associated manual processes u Graphically describes organization of subsystems u Can show type of system l Batch l Real time

11 9 Common System Flow Chart Symbols Figure 9-9

12 9 System Flow Chart for RMO Figure 9-11

13 9 Structure Chart u Describes functions and subfunctions of each part of system u Shows relationships between modules of a computer program u Simple and direct method l Each module performs a specific function l Each layer in a program performs specific activities

14 9 Structure Chart for Entire Payroll Program Figure 9-14

15 9 The Create New Order DFD Fragment Figure 9-17

16 9 Exploded View of Create New Order DFD Figure 9-18

17 9 Rearranged Create New Order DFD Figure 9-19

18 9 First Draft of the Structure Chart Figure 9-20